• TABLE OF CONTENTS
HIDE
 Title Page
 Board of control and staff
 Table of Contents
 Introduction
 Review of literature
 Methods of commercial manufact...
 Experimental procedure
 Oil of orange
 Oil of grapefruit and shaddock
 Oil of Persian seedless lime
 Oil of tangerine
 Citrus stripper oil
 Evaluation of citrus oils
 Summary
 Acknowledgement
 Literature cited














Group Title: Bulletin University of Florida. Agricultural Experiment Station
Title: Essential oils from Florida citrus
CITATION THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00026864/00001
 Material Information
Title: Essential oils from Florida citrus properties and commercial production methods
Series Title: Bulletin University of Florida. Agricultural Experiment Station
Physical Description: 70 p. : ill. ; 23 cm.
Language: English
Creator: Kesterson, J. W
Hendrickson, Rudolph
Publisher: University of Florida Agricultural Experiment Station
Place of Publication: Gainesville Fla
Publication Date: 1953
Copyright Date: 1953
 Subjects
Subject: Citrus oils   ( lcsh )
Citrus fruit industry -- By-products -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: J.W. Kesterson and R. Hendrickson.
Bibliography: Includes bibliographical references (p. 67-70).
General Note: Cover title.
General Note: "A contribution from the Citrus Experiment Station."
 Record Information
Bibliographic ID: UF00026864
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: ltuf - AEN6697
oclc - 18270545
alephbibnum - 000926038

Table of Contents
    Title Page
        Page 1
    Board of control and staff
        Page 2
        Page 3
    Table of Contents
        Page 4
    Introduction
        Page 5
    Review of literature
        Page 6
        Page 7
        Page 8
        Page 9
    Methods of commercial manufacture
        Page 10
        Page 11
        Page 12
        Page 13
        Page 14
        Page 15
        Page 16
    Experimental procedure
        Page 17
        Page 18
        Page 19
    Oil of orange
        Page 20
        Page 21
        Page 22
        Page 23
        Page 24
        Page 25
        Page 26
        Page 27
        Page 28
        Page 29
        Page 30
        Page 31
        Page 32
        Page 33
        Page 34
        Page 35
        Page 36
        Page 37
        Page 38
        Page 39
    Oil of grapefruit and shaddock
        Page 40
        Page 41
        Page 42
        Page 43
    Oil of Persian seedless lime
        Page 44
        Page 45
        Page 46
        Page 47
        Page 48
        Page 49
        Page 50
        Page 51
        Page 52
        Page 53
    Oil of tangerine
        Page 54
    Citrus stripper oil
        Page 55
    Evaluation of citrus oils
        Page 56
        Page 57
        Page 58
        Page 59
        Page 60
        Page 61
        Page 62
        Page 63
        Page 64
        Page 65
    Summary
        Page 66
    Acknowledgement
        Page 67
    Literature cited
        Page 67
        Page 68
        Page 69
        Page 70
Full Text



Bulletin 521 July 1953


UNIVERSITY OF FLORIDA
AGRICULTURAL EXPERIMENT STATIONS
WILLARD M. FIFIELD, Director
GAINESVILLE, FLORIDA
(A Contribution from the Citrus, Experiment Station)








Essential Oils From Florida

Citrus


Properties and Commercial Production Methods



J. W. KESTERSON and R. HENDRICKSON







TECHNICAL BULLETIN







Single copies free to Florida residents on request to
AGRICULTURAL EXPERIMENT STATION
GAINESVILLE, FLORIDA











BOARD OF CONTROL EDITORIAL
J. Francis Cooper, M.S.A., Editor 3
Hollis Rinehart, Chairman, Miami Clyde Beale, A.B.J., Associate Editor s
J. Lee Ballard, St. Petersburg J. N. Joiner, B.S.A., Assistant Editor
Fred H. Kent, Jacksonville William G. Mitchell, A.B.J., Assistant Editor
Wm. H. Dial, Orlando
Mrs. Alfred I. duPont, Jacksonville ENTOMOLOGY
George W. English, Jr., Ft. Lauderdaleh Ento logist
W. Glenn Miller, Monticello A. N. Tissot, Ph.D., Entomologist 1
W. F. Powers, Secretary, Tallahassee L. C. Kuitert, Ph.D., Associate
H. E. Bratley, M.S.A., Assistanir
EXECUTIVE STAFF F. A. Robinson, M.S., Asst. Apiculturist
R. E. Waites, Ph.D., Asst. Entomologist
J. Hillis Miller, Ph.D., President -
J. Wayne Reitz, Ph.D., Provost for Agr.3 HOME ECONOMICS
Willard M. Fifield, M.S., Director Ouida D. Abbott Ph.D., Home Econ.1
J. R. Beckenbach, Ph.D., Asso. Director R. B. French, Ph.D., Biochemist
L. O. Gratz, Ph.D., Assistant Director French, Ph.D., iocemist
Rogers L. Bartley, B.S., Admin. Mgr.3 HORTICULTURE
Geo. R. Freeman, B.S., Farm Superintendent
G. H. Blackmon, M.S.A., Horticulturist 1
F. S. Jamison, Ph.D., Horticulturist 34
MAIN STATION, GAINESVILLE Albert P. Lorz, Ph.D., Horticulturist
R. K. Showalter, M.S., Asso. Hort.
R. A. Dennison, Ph.D., Asso. Hort.
AGRICULTURAL ECONOMICS R. H. Sharpe, M.S., Asso. Horticulturist
H. G. Hamilton, Ph.D., Agr. Economist 1 V. F. Nettles, Ph.D., Asso. Horticulturist
H. G. Hamlton, Ph.D., Agr. Economist F S. Lagasse, Ph.D., Horticulturist2
R. E. L. Greene, Ph.D., Agr. Economist R. D. Dickey, M.S.A., Asso. Ifort.
M. A. Brooker, Ph.D., Agr. Economist a L. H. Dickey, M.S.A., Asst. Short.
Zach Savage, M.S.A., Associate Halsey, M.S.A., Asst. Horticulturist
C. B. Hall, Ph.D., Asst. Horticulturist
A. H. Spurlock, M.S.A., Agr. Economist Austin Griffiths, Jr., B.S., Asst. Hort.
D. E. Alleger, M.S., Associate S. E. McFadden, Jr., Ph.D., Asst. Hort.
D. L. Brooke, M.S.A., Associate C. H. VanMiddelem, Ph.D., Asst. Biochemist
M. R. Godwin, Ph.D., Associate Buford D. Thompson, M.S.A., Asst. Hort.
W. K. McPherson, M.S., Economist 3 M. W. Hoover, M.S.A., Asst. Hort.
Eric Thor, M.S., Asso. Agr. Economist M Hoover A., Asst.
Cecil N. Smith, M.A., Asso. Agr. Economist LIBRARY
Levi A. Powell, Sr., M.S.A., Assistant
Orlando, Florida (Cooperative USDA) Ida Keeling Cresap, Librarian
G. Norman Rose, B.S., Asso. Agri. Economist
J. C. Townsend, Jr., B.S.A., Agricultural PLANT PATHOLOGY
Statistician 2 W. B. Tisdale, Ph.D., Plant Pathologist1 3
J. B. Owens, B.S.A., Agr. Statistician 2 Phares Decker, Ph.D., Plant Pathologist
AGRICULTURAL ENGINEERING Erdman West, M.S., Botanist & Mycologist 3
Robert W. Earhart, Ph.D., Plant Path.2
Frazier Rogers, M.S.A., Agr. Engineer13 Howard N. Miller, Ph.D., Asso. Plant Path.
J. M. Myers, M.S.A., Asso. Agr. Engineer Lillian E. Arnold, M.S., Asso. Botanist
J. S. Norton, M.S., Asst. Agr. Engineer C. W. Anderson, Ph.D., Asst. Plant Path.
AGRONOMY POULTRY HUSBANDRY
Fred H. Hull, Ph.D., Agronomist' N. R. Mehrhof, M.Agr., Poultry Husb. 3
G. B. Killinger, Ph.D., Agronomist J. C. Driggers, Ph.D., Asso. Poultry Husb.3
H. C. Harris, Ph.D., Agronomist
R. W. Bledsoe, Ph.D., Agronomist SOILS
W. A. Carver, Ph.D., Agronomist
Fred A. Clark, M.S., Associate2 F. B. Smith, Ph.D., Microbiologis't 1
E. S. Horner, Ph.D., Assistant Gaylord M. Volk, Ph.D., Soils Chemist
A. T. Wallace, Ph.D., Assistant J. R. Neller, Ph.D., Soils Chemist
D. E. McCloud, Ph.D., Assistant3 Nathan Gammon, Jr., Ph.D., Soils Chemist
G. C. Nutter, Ph.D., Asst. Agronomist Ralph G. Leighty, B.S., Asst. Soil Surveyor
G. D. Thornton, Ph.D., Microbiologist
ANIMAL HUSBANDRY AND NUTRITION C. F. Eno, Ph.D., Asst. Soils Microbiologist
T. J. Cunha, Ph.D., Animal Husbandman3 H. W. Winsor, B.S.A., Assistant Chemist
G. K. Davis, Ph.D., Animal Nutritionist Calile, .S., Asst. Soil Surveyor
R. L. Shirley, Ph.D., Biochemist VW. Carlisle, B.S, Asst. Soil Surveyor
A. M. Pearson, Ph.D., Asso. An. Husb. J. H. Walker, M.S.A., Asst. Soil Surveyor
JoA. Fearsne, Ph.D., Asso. An. Nutri. William K. Robertson, Ph.D., Asst. Chemist
John P. Feaster, Ph.D., Asst. An. Nutri. 0. E Cruz, B.S.A., Asst. Soil Surveyor
H. D. Wallace, Ph.D., Asst. An. Husb.3 e
M. Koger, Ph.D., An. Husbandman W. G. Blue, Ph.D., Asst. Biochemist
J. Hentges Jr, Ph.D., Asst. An. Hush. 3 J. G. A. Fiskel, Ph.D., Asst. Biochemist 3
L. IArrington, Ph.D., Asst. An. Husb. L. C. Hammond, Ph.D., Asst. Soil Physicist 3
H. L. Breland, Ph.D., Asst. Soils Chem.
DAIRY SCIENCE VETERINARY SCIENCE
E. L. Fouts, Ph.D., Dairy Technologist '
R. B. Becker, Ph.D., Dairy Husbandman 3 D. A. Sanders, D.V.M., Veterinarian 1'
S. P. Marshall, Ph.D., Asso. Dairy Husb.3 M. W. Emmel, D.V.M., Veterinarian
W. A. Krienke, M.S., Asso. Dairy Tech.3 C. F. Simpson, D.V.M., Asso. Veterinarian
P. T. Dix Arnold, M.S.A., Asso. Dairy lHusb. 3 L. E. Swanson, D.V.M., Parasitologist
Leon Mull, Ph.D., Asso. Dairy Tech.3 W. R. Dennis, D.V.M., Asst. Parasitologist
H. H. Wilkowske, Ph.D., Asst. Dairy Tech.3 E. W. Swarthout, D.V.M., Asso. Poultry
James M. Wing, Ph.D., Asst. Dairy Husb. Pathologist (Dade City)












BRANCH STATIONS F. T. Boyd, Ph.D., Asso. Agronomist
M. G. Hamilton, Ph.D., Asst. Horticulturist
NORTH FLORIDA STATION, QUINCY
W. C. Rhoades, Jr., M.S., Entomologist in SUB-TROPICAL STATION, HOMESTEAD
Charge Geo. D. Ruehle, Ph.D., Vice-Dir. in Charge
R. R. Kincaid, Ph.D., Plant Pathologist D. O. Wolfenbarger, Ph.D., Entomologist
L. G. Thompson, Jr., Ph.D., Soils Chemist Francis B. Lincoln, Ph.D., Horticulturist
W. H. Chapman, M.S., Agronomist Robert A. Conover, Ph.D., Plant Path.
Frank S. Baker, Jr., B.S., Asst. An. Hush. John L. Malcolm, Ph.D., Asso. Soils Chemist
Frank E. Gutbrie, Ph.D., Asst. Entomologist R. W. Harkness, Ph.D., Asst. Chemist
R. Bruce Ledin, Ph.D., Asst. Hort.
Mobile Unit, Monticello J. C. Noonan, M.S., Asst. Hort.
R. W. Wallace, B.S., Associate Agronomist M. H. Gallatin, B.S., Soil Conservationist2
Mobile Unit Marianna WEST CENTRAL FLORIDA STATION,
R. W. Lipscomb, M.S., Associate Agronomist BROOKSVILLE
Mobile Unit, Pensacola Marian W. Hazen, M.S., Animal Husband-
R. L. Smith, M.S., Associate Agronomist man in Charge2
Mobile Unit, Chipley
Mobile- Unit, ChRANGE CATTLE STATION, ONA
J. B. White, B.S.A., Associate Agronomist R GE TLE ST ,
W. G. Kirk, Ph.D., Vice-Director in Charge
CITRUS STATION, LAKE ALFRED E. M. Hodges, Ph.D., Agronomist
A. F. Camp, Ph.D., Vice-Director in Charge D. W. Jones, M.S., Asat. Soil Technologist
W. L. Thompson, B.S., Entomologist
R. F. Suit, Ph.D., Plant Pathologist CENTRAL FLORIDA STATION, SANFORD
E. P. Ducharme, Ph.D., Asso. Plant Path. R. W. Ruprecht, Ph.D., Vice-Dir. in Charge
C. R. Stearns, Jr., B.S.A., Asso. Chemist J. W. Wilson, ScD., Entomologist
J. W. Sites, Ph.D., Horticulturist P. J. Westgate, Ph.D., Asso. Hort.
H. 0. Sterling, B.S., Asst. Horticulturist Ben F. Whitner, Jr., B.S.A., Asst. Hort.
H. J. Reitz, Ph.D., Horticulturist Geo. Swank, Jr., Ph.IY., Asst. Plant Path.
Francine Fisher, M.S., Asst. Plant Path.
I. W. Wander, Ph.D., Soils Chemist
J. W. Kesterson, M.S., Asso. Chemist WEST FLORIDA STATION, JAY
R. Hendrickson, B.S., Asst. Chemist C. E. Hutton, Ph.D., Vice-Director in Charge
Ivan Stewart, Ph.D., Asst. Biochemist H. W. Lundy, B.S.A., Associate Agronomist
D. S. Prosser, Jr., B.S., Asst. Engineer
R. W. iOlsen, B.S., Biochemist
F. W .Wenel, Jr., Ph.D., Chemist SUWANNEE VALLEY STATION,
Alvin H. Rouse, M.S., Asso. Chemist LIVE OAK
H. W. Ford, Ph.D., Asst. Horticulturist
L. C. Knorr, Ph.D., Asso. Histologist G. E. Ritchey, M.S., Agronomist in Charge
R. M. Pratt, Ph.D., Asso. Ent.-Pathologist G F C S ,
W. A. Simanton, Ph.D., Entomologist GULF COAST STATION, BRADENTON
E. J. Deszyck, Ph.D., Asso. Horticulturist E. L. Spencer, Ph.D., Soils Chemist in Charge
C. D. Leonard, Ph.D., Asso. Horticulturist E. G. Kelsheimer, Ph.D., Entomologist
W. T. Long, MS., Asst. Horticulturist David G. A. Kelbert, Asso. Horticulturist
M. H. Muma, Ph.D., Asso. Entomologist Robert 0. Magie, Ph.D., Plant Pathologist
F. J. Reynolds, Ph.D., Asso. Short. J. M. Walter, Ph.D., Plant Pathologist
W. F. Spencer, Ph.D., Asst. Chem. S. S. Wolt, Ph.D., Asst. Horticulturist
R. B. Johnson, Ph.D., Asst. Entomologist Donald S. Burgis, M.S.A., Asst. Hort.
W. F. Newhall, Ph.D., Asst. Entomologist C. M. Geraldson, Ph.D., Asst. Horticulturist
W. F. Grierson-Jackson, Ph.D., Asst. Chem.
Roger Patrick, Ph.D., Bacteriologist
Marion F. Oberbacher, Ph.D., Asst. Plant FIELD LABORATORIES
Physiologist
Evert J. Elvin, B.S., Asst. Horticulturist Watermelon, Grape, Pasture-Leesburg
R. C. J. Koo, Ph.D., Asst. Biochemist
J. R. Kuykendall, Ph.D., Asst. Horticulturist J. M. Crall, Ph.D., Associate Plant Path-
ologist Acting in Charge
EVERGLADES STATION, BELLE GLADE C. C. Helms, Jr., B.S., Asst. Agronomist
L. H. Stover, Assistant in Horticulture
W. T. Forsee, Jr., Ph.D., Chemist in Charge
R. V. Allison, Ph.D., Fiber Technologist Strawberry-Plant City
Thomas Bregger, Ph.D., Physiologist A. N. Brooks, Ph.D., Plant Pathologist
J. W. Randolph, M.S., Agricultural Engr.
R. W. Kidder, M.S., Asso. Animal Husb. Vegetables-Hastings
C. C. Seale, Associate Agronomist A. H. Eddins, Ph.D., Plant Path. in Charge
N. C. Hayslip, B.S.A. Asso. Entomologist E. N. McCubbin, Ph.D., Horticulturist
E. A. Wolf, M.S., Asst. Horticulturist T. M. Dobrovsky, Ph.D., Asst. Entomologist
W. H. Thames, M.S., Asst. Entomologist
W. G. Genung, M.S., Asst. Entomologist Pecans-Monticello
Frank V. Stevenson, M.S., Asso. Plant Path. A. M. Phillips, B.S., Asso. Entomologist2
Robert J. Allen, Ph.D., Asst. Agronomist John R. Large, M.S., Asso. Plant Path.
V. E. Green, Ph.D., Asst. Agronomist
J. F. Darby, Ph.D., Asst. Plant Path. Frost Forecasting-Lakeland
V. L. Guzman, Ph.D., Asst. Hort. Warren O. Johnson, B.S., Meteorologist in
J. C. Stephens, B.S., Drainage Engineer 2 Charge 2
A. E. Kretschmer, Jr., Ph.D., Asst. Soils
Chem. 1 Head of Department
Charles T. Ozaki, Ph.D., Asst. Chemist 2 In cooperation with U. S.
Thomas L. Meade, Ph.D., Asst. An. Nutri. Cooperative, other divisions, U. of F.
U. S. Harrison, M.S., Asst. Agri. Engr. 4 On leave










CONTENTS
PAGE
INTRODUCTION ..... .---........- --. --.............. ........... ................ .. 5
REVIEW OF LITERATURE ....--.........--.....-.....--.........-- ........-.......... 6
METHODS OF COMMERCIAL MANUFACTURE ....-......---- ... ..--- ..-- .....-- .... 10
Coldpressed Oils ..............-----------....................................... 10
General Processing Procedure ............--..--...--.....-..--............ 10
Pipkin Roll Method of Extraction ...........---......--- ......-- ......... 10
Screw Press Method of Extraction .......---.................................. 11
Fraser-Brace Extractor ...........--------..... --......--.................. 13
Pipkin Juice Extractor ............. .........-........ --................. 13
D istilled Oils ..................... .... ............. ........ ...... ............... 15
EXPERIMENTAL PROCEDURE .. ---.-------------- --.............. .............-- 17
Survey of Commercial Plants .............----...-- .....----.........-...... 17
Collection of Samples ....................- ................-- ...... ..... .... 17
Methods of Analyses ..-........ .... --....---.....------................. -20
OIL OF ORANGE ....... ........-----------------............-- ....----- --......... ......... 20
Coldpressed Oil of Orange ..................... ........................ ..... .......__- 20
Relation of Yield to Properties and U. S. P. Specifications .......... 29
Effect of Aqueous Phase of Aldehyde Content ................................ 31
Relation of Fruit Variety to Properties ....................-- ...-- ............. 33
Storage of Fruit Prior to Oil Extraction ...---.......--.........--........--.. 33
Effect of Maturity on Properties ...................--...........--......... 34
Effect of Yearly Variations on Properties .................................... 34
Comparison of Florida Coldpressed Orange Oil with Oils from
Other Sources ....................--.....---...----....--........ ..... 36
Distilled Oil of Orange ........- ..--- ---...................................... 36
OIL OF GRAPEFRUIT AND SHADDOCK ..........------ ......---... -----......... 40
Coldpressed Oil of Grapefruit .................-----..--.....---.......- 40
Experimental Samples .----........---......... ... -............-. 40
Commercial Samples .........----...--...-...... ...------........ 40
Coldpressed Oil of Shaddock ............---...---....-----.......... ..... .. 42
Distilled Oil of Grapefruit -----.......-.. .......... ---..... ................ 44
OIL OF PERSIAN SEEDLESS LIME ...--........------------....... ......---- .....-... 44
Coldpressed Oil of Lime ....--..-- .. .......------..............--.. 47
Relation of Yield to Properties ........... ---------............ --- ........ 48
Effect of Aqueous Phase on Aldehyde Content ........- --..........-- .....-. 48
Comparison of Coldpressed Oils .................---......--- ......... 49
Distilled Oil of Lime .......-- ......--- ..------... ----.........-----..... .............--... 50
Effect of Coldpressing Peel Prior to Distillation ----...----------......... 51
Comparison of the Distilled Oils .----... ---.... -----.-----............ 52
OIL OF TANGERINE .....-- ........--- .......... ...---..-.....--... 54
CITRUS STRIPPER OIL ------------...........-.............-....-......-------- ....... 55
EVALUATION OF CITRUS OILS -----------. ....----------............-- ...... 56
Experimental Method .....- ...... -....- -.......----.....-----..... ... ...... 56
Discussion of Experimental Method --......-.........-- ....-- ...----.......... 58
Evaluation of Florida Coldpressed Orange Oil ......-----.........---........... 59
Evaluation of California Coldpressed Orange Oil ....-....................-...... 62
Anti-Oxidants for Orange Oil ..........-----.....----....---.................. 65
SUMMARY ........------ -.--..----- ---...... .. --................----------------... 66
ACKNOWLEDGMENTS .....----.--..........-----------................ 67
LITERATURE CITED ...-----.........--....-.. -----... --.................... 67










Essential Oils from Florida Citrus1

Properties and Commercial Production Methods

J. W. KESTERSON 2 and R. HENDRICKSON 3

INTRODUCTION
The processing of citrus fruits is a vast and important part
of the Florida citrus economy today. This industry has grown
to such proportions that more than half of the Florida orange
and grapefruit crop is now processed, as shown by Table 1. The
principal and primary products that result from the processing of
this huge quantity of fruit are canned single strength juice,
frozen and hot pack concentrated citrus juices, and canned citrus
sections.
TABLE 1.-NUMBER OF BOXES AND PERCENT OF FLORIDA ORANGES AND
GRAPEFRUIT UTILIZED IN PROCESSING CHANNELS (6) .

Season Oranges Processed Grapefruit Processed
1,000 Boxes | Percent 1,000 Boxes Percent
1946-47 19,886 38 15,866 60
1947-48 30,421 52 19,448 67
1948-49 26,813 47 16,306 55
1949-50 34,657 62 13,486 60
1950-51 41,857 65 17,812 56


After the juice has been extracted, over half of the weight
of the citrus fruit remains as cannery refuse consisting of peel,
pulp, rag, and seeds. During the past 15 years an entirely new
industry has developed to utilize these enormous quantities of
refuse from the canneries which formerly were considered waste
products, but which are now fundamental in the economy of
Florida's citrus industry.
The essential oil, found in the peel of the fruit, is the first
product recovered from cannery refuse. Oil of orange is the
most useful of the citrus oils produced in Florida. It commands
a price which justifies, economically, the operation of a plant
for its recovery.

1A revision of Florida Agricultural Experiment Station Bulletin 452,
Florida Citrus Oils, by J. W. Kesterson and O. R. McDuff.
2 Associate Chemist, Citrus Experiment Station, Lake Alfred, Florida.
SAssistant Chemist, Citrus Experiment Station, Lake Alfred, Florida.
Italic figures in parentheses refer to Literature Cited in the back of
this bulletin.








6 Florida Agricultural Experiment Stations

The principal purpose of the investigations presented in this
publication was to determine by what means essential oils of
very high quality could be produced. Through the use of the
information obtained to date, it has been possible for the citrus
industry in Florida to produce citrus oils which consistently
meet the specifications of the United States Pharmacopoeia
(38), as well as other quality requirements of essential-oil con-
sumers throughout the country. Production of oils of highest
quality and uniformity has resulted in a larger consumer market.
Another purpose of the work was to determine the relationship
between the physical and chemical characteristics of the various
types of oils, and such factors as methods of extraction, methods
of processing, fruit variety, and fruit maturity.

REVIEW OF LITERATURE
Many investigators have pointed out that the quality of citrus
oils is dependent upon many factors. Some of these are soil,
climate, method of extraction of the oil, weather, and maturity
of the fruit.
Citrus oils are contained in oval, balloon-shaped oil sacs or
vesicles located in the outer rind or flavedo of the fruit. Winton
and Winton (40) described the exact location of these oil sacs
in their discussion of the microscopic structure of the flavedo of
the orange. Hood (17) found a wide variation in the oil yield
of Florida oranges, reporting values of 0.11 to 0.58 percent calcu-
lated on the weight of the whole fruit. He stated that the oil con-
tent does not reach its maximum until the oranges are fully
mature, but is present in commercial quantities before the fruit is
ready for harvest. He also noted that a decrease in oil content
immediately follows a period of rainfall. Bartholomew and Sin-
clair (3) studied the effect of age, size, and environment on the
relative amounts of oil in California oranges. Atkins, Wieder-
hold, and Heid (2) reported the oil content of cull Persian limes
to be 0.32 percent on a whole-fruit basis.
To secure the oil from the peel of citrus fruits, the oil sacs
must be punctured by either pressure or rasping. Methods of
oil extraction used in Florida during the 1937-38 season were
investigated by von Loesecke and Pulley (39). They showed
that the method of extraction had an effect upon the physical
characteristics of the oil. However, they did not find any rela-
tion between the time of year and the physical character-
istics. They reported that there were no great differences in







Essential Oils from Florida Citrus 7

the properties of the oil from different fruit varieties or from
fruit produced in different counties.
Atkins, Wiederhold, and Held (2) extracted oil from cull limes
by using a screw press and a Pipkin (34) press. The centrifug-
ing of lime oil emulsions has been discussed by Moore, Atkins,
and Wiederhold (29). Guenther (15), in a recent series of ar-
ticles, has reviewed methods of oil extraction used in the United
States and in foreign countries. He stated that the method of
oil extraction and the amount of carrier water used in a process
affect the quality of the oil.
The physical and chemical characteristics of Florida orange,
grapefruit, tangerine, and lime oils have been reported by many
investigators (2, 7, 11, 13, 16, 30, 31, 39). Some of these re-
ported results are presented in Table 2, which also includes
values for oils from other sources as reported by Poore (35) and
Guenther (9, 11). Foote and Gelpi (7) noted variations in the
properties of different lots of Floridian oil of orange. They also
suggested that producers should unite in the blending and mar-
keting of their oils in an effort to maintain the same quality
from year to year.
Nelson (30), Nelson and Mottern (31, 32), and Markley, Nel-
son, and Sherman (28) have carried out investigations relative
to the chemical constituents of orange, grapefruit, and tangerine
oils produced in Florida.
Guenther (10) stated that Naves reported that Guinea orange
oils extracted from fully matured fruit showed a higher specific
gravity, refractive index, aldehyde content, and evaporation
residue, but a lower optical rotation, than oils pressed from
green fruit.
When oranges were kept in cold storage for periods longer
than six weeks previous to the extraction of the oil, de Villiers
(4) found an increase in the specific gravity, optical rotation,
iodine number, and saponification value, but a decrease in the
aldehyde content of the oil.
Kesterson et al. (19, 20, 21, 22, 23) have carried out studies
relative to the chemical and physical properties of orange, grape-
fruit, tangerine and Persian lime oils produced in Florida.
The deterioration of orange oil as well as the effects of anti-
oxidants, has been investigated by Kesterson and McDuff (24)
and Kesterson and Hendrickson (25, 26) as well as by Proctor
and Kenyon (36, 18) and Flores and Morse (5).







TABLE 2.-PROPERTIES OF CITRUS OILS AS REPORTED BY OTHER INVESTIGATORS.
Florida California
Coldpressed Coldpressed Coldpressed Other Florida Distilled Oils
Orange Orange Orange Coldpressed Oils_
Reference ] I Cali-
U.S.P. XIII Source I Source 2 Valencia Navel Grapefruit Tange- Lime fornia Florida
Specifications I rine I Orange Lime
(38) (89) (7) (35) (35) (31) (18) (11) (9) (11)
Specific 0.842 0.840
gravity to 0.8434 0.8425 0.8440 0.8455 0.8563 0.845 0.886 to 0.8632
(25C./25C.) 0.846 (20"C./20C.) (15C.) 0.842 (15C.)

Refractive 1.4723 1.4717
index to 1.4726 1.4734 1.4735 1.4738 1.4758 1.4748 1.4855 to 1.4759
(20C.) 1.4737 1.4730

Evaporation not less
residue than 4.18 2.80 3.61 4.53 7 to 8 3.3 13.0 0.5 to 1
% 1.7% 1

Optical not less than +98
rotation +94, and not +96.49 +95.5 +97.78 +96.93 +93.280 +92.50 +41.26 to +43.20
(25C.) more than +99 (200C.) (20C.) (20C.) +99.1 .
Iin 100 mm tube ___

S Optical equal to original
Rotation oil or not more +97.55 +97.5 +99.210 +98.71
S (25C.) than 2 (20C.) (20C.)
difference
R not less than
Refractive 0.0008 and not
index more than 0.0015 1.4719 1.4729 1.4723 1.4724
" (20C.) lower than
I original oil *








Essential Oils from Florida Citrus 9

Fundamental information relative to all types of essential
oils produced throughout the world is found in Perry (33) and
in Gildemeister and Hoffman (8). Guenther (14) has published
a series of six volumes in which he has brought the whole subject
up to date. In this work he ably presents information on the
production, chemistry, analysis, and uses of the essential oils.






































Fig. 1.-Pipkin roll. (Photograph courtesy Essential Oil Producers, Inc.,
Dunedin, Fla.)








10 Florida Agricultural Experiment Stations

Regardless of the profusion of literature, sufficient knowledge
concerning the character of oils produced in Florida has been
lacking. Such information must necessarily represent broad-
scale sampling to include the effects of varieties, season, and
methods of extraction if an accurate picture of the production
is to be presented. In this work the writers have attempted
to produce an accurate broad-scale picture that covers the en-
tire production in Florida.

METHODS OF COMMERCIAL MANUFACTURE
COLDPRESSED OILS
General Processing Procedure.-Citrus peel oils are expressed
in Florida by four different types of equipment: (1) Pipkin
roll, (2) screw press, (3) Fraser-Brace extractor, and (4) Pipkin
juice extractor. The general processing procedure, used after
the extraction of oil from the peel, is very similar in most of
the commercial plants. All of the above methods of extraction
give an emulsion of oil and water. The oil is separated centri-
fugally from the aqueous phase by passing the emulsion through
a sludger (8,000-10,000 r.p.m.) and then through a polisher
(16,000-18,000 r.p.m.).
Following separation, the oil is stored for approximately one
week at 32-400 F. During this winterizing treatment, unde-
sirable waxy materials separate from the oil and are allowed
to settle. The clear oil is decanted into stainless steel storage
tanks or tin-dipped containers, which are then maintained at
a storage temperature of about 400 F. Air is usually excluded
from the container to prevent deterioration. Exclusion of air
usually is accomplished either by filling the container full of
oil or by displacement of the air with carbon dioxide.
Pipkin Roll Method of Extraction.-A Pipkin Roll (34) is
shown in Fig. 1, and the flow and material balance sheet for this
process is given in Fig. 2. In this method the oil is expressed
by passing peel of the fruit between two striated rollers of
stainless steel that turn in opposite directions. The distance
between the two rollers is adjusted so that the pressure against
the peel is just sufficient to puncture the oil cells without break-
ing or rasping the peel. Small striations or grooves are dis-
tributed over the entire surface of the rolls. They are of a
depth sufficient to receive the oil from the oil cells, thereby keep-











Essential Oils from Florida Citrus 11


ing it out of contact with the peel and thus eliminating to some

extent its absorption by the albedo of the fruit.

Screw Press Method of Extraction.-In this method tapered
screws press the crushed peel against a perforated screen, there-
by squeezing out the oil. This operation can be carried out






CITRUS PEEL

JUICE PLANT
22.5 TON/HR

Y IEL B S L OILTONPEE
PIPKIN ROLL PIPKIN ROLL PIPKIN ROLL PIPKIN ROLL
6.s TON/HR 56 TON/HR. 5. TON/HR. 8.6 TON/HR.


PRESS EFFLUENT P PRESS EFFLUET PRESS EPLUENT PRESS EFFLUENT





STORAGE STORE
TANK TANK








128 GAL./HR. EFFLUENT


I SLUDGE I EO



POLISHER EFFLUENT
SHARPLES FROM
18000 R.RM. POLISHER


PEEL OIL
COLD PRESSED
6 GAL./HR.





PIPKIN ROLL
FLOW AND MATERIAL BALANCE SHEET
COLD PRESSED CITRUS PEEL OIL MANUFACTURE
AQUEOUS PHASE 21.5 GAL./GAL OIL
YIELD 1.81 LB. OIL/TON PEEL
VARIETY LATE SEASON ORANGES

APIL I, 1O4 W IODUf


Fig. 2.-Flow and material balance sheet for process using Pipkin roll.











12 Florida Agricultural Experiment Stations



with the screws in either a vertical or horizontal position. Water

may, or may not, be used in the pressing operation. Figure 3

is a flow and material balance sheet for the manufacture of cold-

pressed citrus peel oil by the use of screw presses.





CENTRIFUGE & SLUDGE FROU MAKE- UP WATER
EFFLUENT JUICE PLANT00 L.R
1200 GAL./HR. 0 TON/HR.
0O TON/HR.


SCREW PRESS SREW PRESS
10to TOT/HR. 10 to TOM/HR.


PRESS EFFLUENT PRESS EFFLUENT
1250 GAL./HR. 1 50 OGAL./HR.


1l00 GAL./HR. GENT. EFF.
BOO GAL./HR. MAKE-UP WATER
500 GAL./HR PRESS EFF.
2500 GAL./HR. TOTAL


SLUDGER
DELAVAL SLUDGE MAKE-UP WATER
6000 R.PM. 43 GAL./HR. 175 GAL./HR.
2500 GAL./HR.




SLUDGE EFFLUENT
2457 GAL./HR.

CENTRIFUGE B SLUDGE
EFFLUENT __ CENTRIFUGE
2661 SAL./HR.
2661 AL.HI L CENTRIFUGE EFFLUENT D OELAVAL
S*204 GAL./HR. 6500 RAM.

CENTRIFUGE & SLUDGE S18 GAL./MR.
EFFLUENT
TO
MOLASSES PLANT
1461 GAL./HR. POLSHER
(3-6* BRIX) SHARPLES
8000 R.P.M.
14 GAL./HR.


COLD PRESSED
PEEL OIL
14 GAL./HR.




SCREW PRESS
FLOW AND MATERIAL BALANCE SHEET
COLD PRESSED CITRUS PEEL OIL MANUFACTURE

AQUEOUS PHASE 190 GAL./GAL. OIL
YIELD 4.90 LB. OIL/TON PEEL
VARIETY MIDSEASON ORANGES

NAM 9 1042 .. W KneOT |O
F Aig M IF a4 n maOMR s t. MODUFP


Fig. 3.-Flow and material balance sheet for process using screw press.







Essential Oils from Florida Citrus 13

Fraser-Brace Extractor.-Whole fruit is passed through a
corridor of carborundum rolls in this process, as shown in Fig.
4. As the fruit passes through the extractor, it is turned over
and over and abrasive rolls rasp the flavedo from the fruit.
Water sprays are directed onto the fruit and rolls to wash away
the oil and grated peel. The oil and water emulsion is passed
over a screen to remove the suspended solid particles. Then
it is transferred to settling tanks, where it is held from three
to 12 hours to effect complete settling and to allow the emulsion
to break. The machine is completely enclosed and very little
loss of oil is encountered. Figure 5 is a flow and material balance
sheet for this process.







o00 0o0






@ @ @ @ @
000 OoO\4OoO

ABRASIVE ROLLS



CROSS SECTION 3-TUNNEL GRATER

Fig. 4.-Cross-section diagram of Fraser-Brace extractor. (Courtesy
Fraser-Brace Engineering Co., Tampa.)
Pipkin Juice Extractor.-The Pipkin juice extractor (Fig. 6)
provides a method whereby both the juice and the peel oil
from whole fruit are secured simultaneously, but in such a
manner that they do not come in contact with each other to any










14 Florida Agricultural Experiment Stations


great extent. This machine is of the rotary type and has 24

squeezing heads, which are all actuated by a common cam. The

extractor is furnished complete with a feeder mechanism and

a built-in electric power unit. Whole fruit is fed into a squeez-

ing cup where just enough pressure is applied to remove all

juice from the fruit and at the same time rupture the oil cells.

The juice and the oil emulsion are collected in separate trough







MAKE UP WXT
... .=LI









Soo eAL.IH.I


ROTARY SCREEN -
oo SeAL*I Ian 11
. .- - ---1 - ~







.NOH TIME I-a
I I I I *


















SLUDGE
81OIL6 10 SML..P U

ROTAR I SCREE









SL SLUDGE







O TEA LUET RWAW STO
LD PEE 0L MA

AUEU PHASE 00 I AL/ALAL. GENTRIFUE




YIELD .*S P. LM. MLITON PELL

VARIETY EAO RA
AQUEOU5 PASSE .00 ALAL.OIL a 05K/S


SPRAT ImZZLI0 S I, 4
JT ESLUD:E





EXTRAOTORS 5 + , 8a
STORAGE TANKS 10, 11, II 1
1MASE. .. 'a R' W. *a`G SDST-s
MIS0 S. Ki l' OD Ine
M AIle 31, I XTI IO Oln ,tlSD





Fig. 5.-Flow and material balance sheet for process using Fraser-
Brace extractor.








Essential Oils from Florida Citrus 15

assemblies. The flow and material balance sheet for this process
is given in Fig. 7.
DISTILLED OILS
Distilled oil of orange, grapefruit, or tangerine is secured by
some processors as a by-product in the canning of citrus fruit
juices. Some of the citrus peel oil becomes mixed with the
juice as it is extracted by the various types of juice extractors
used in the canneries. Excessive amounts of peel oil in the
juice are detrimental to the quality of the canned juice; there-
fore, in most canning plants the oil content of the juice is re-
duced to a desirable level by passing the juice through a deoiler.
The juice is usually flashed in the deoiler, which is operated under
a vacuum of 11 in. (1900 F.) to 25.5 in. (130 F.), and a vapor
mixture of oil and water is removed. Then the mixture of oil
and water vapors is condensed and the oil is separated from

Fig. 6.-Pipkin juice extractor. (Photograph courtesy Food Machinery
Corp., Lakeland, Fla.)





till.








.4 T,'



i j).6










16 Florida Agricultural Experiment Stations


the condensate by decantation or centrifuging. Vacuum steam-
distilled oils, which are manufactured in this manner, have
slightly different properties than oils which are obtained by
steam distillation at atmospheric pressure.

Stripper oils are obtained as a by-product from the manufac-
ture of citrus molasses, which is made from the press liquor
from plants manufacturing dried citrus pulp for cattle feed.






PIPKIN JUICE EXTRACTOR a JUI
TO
FO TOR FRUIT EANNINA PLANT





OIL SLURRY
HOLDING TANK

s5OO AL.




SLIDER SLUDGE
.sApL1S EFFLUENT




SLUDGE





uftRPlr EFFLUENT




COLD PRESSED
PLEL OIL PIPKIN JUICE EXTRACTOR
FLOW AND MATERIAL BALANCE SHEET
40 *AL.OIL COLD PRESSED .ITRUS PEEL OIL MANUFACTURE

AQUEOUS PHASE 18.5 GAL./ GAL. OIL
YIELD 7.0 LB. OIL / TON PEEL
VARIETY MIDSEASON ORANGES
JAMES W. KIDSTE"ION
APRIL I.* 1941 OME R. M.OUFF

Fig. 7.-Flow and material balance sheet for process using Pipkin
juice extractor.








Essential Oils from Florida Citrus 17

EXPERIMENTAL PROCEDURE
SURVEY OF COMMERCIAL PLANTS
Information pertaining to the various processes used in Flor-
ida for the manufacture of expressed and distilled citrus peel
oils was secured through the helpful cooperation of commercial
processors. In order to secure the data used in the preparation
of flow and material balance sheets, the authors visited plants
employing the various methods of oil extraction. Rate of flow
measurements were made on each unit process operation for
each individual process. Data were taken covering periods of
operation of 4 to 24 hours' duration. Information obtained from
each study was incorporated in a flow and material balance dia-
gram for that particular process, and these are presented in
Figs. 2, 3, 5, and 7.

COLLECTION OF SAMPLES
More than 400 samples of various types of coldpressed and
distilled citrus oils were secured from commercial processing
plants during the course of this study.
Two hundred and forty-three samples of coldpressed oils of
orange, grapefruit, and tangerine were secured from four plants,
each of which was using a different method for the extraction
of the oil from the peel. These samples were taken once a
month from lots of oil ranging from 500 to 11,000 pounds, which
represented the production for approximately one week.
One plant furnished 12 samples of expressed orange oil,
which were analyzed to determine if storage of the fruit for
several days prior to the extraction of the oil would cause any
change in the physical and chemical characteristics of the
oil. Part of a selected lot of Valencia oranges was processed
through the oil plant on the day it was picked and an equal
quantity of the same lot of fruit was held in storage bins from
three to five days before the oil was extracted. Each compara-
tive set of samples was made by the same type of extractor
under exactly the same conditions. These 12 samples were
representative of 132,000 pounds of oil extracted from approxi-
mately 840,000 boxes of fruit.
Samples of distilled oils of orange and grapefruit from 250
to 350-pound batches of oil were collected from five canneries
and a total of 18 samples were secured.





TABLE 3.-THE PHYSICAL AND CHEMICAL PROPERTIES OF COLDPRESSED ORANGE OILS PRODUCED IN FLORIDA.
1 I Refrac- 1 I -
Refrac- tive Optical Aide- Evapor-
Type Variety Specific tive Index Optical Rotation hyde Ester action
of of Gravity Index of 10% Differ- Rotation of 10% Differ- Con- Con- Resi-
Extractor Fruit* 25C./25C. 20 Distillate ence 25 Distillate ence tent tent due
D 20 D 25 % % %
D D
October, 1947
Pipkin juice J
extractor 1100% H 0.8433 1.4729 1.4714 0.0015 +97.57 +97.75 0.18 1.17 0.44 2.52
50% H
Screw press 50% PB 0.8419 1.4723 1.4708 0.0015 +97.57 +97.75 0.18 1.01 0.42 2.20
November, 1947
Pipkin juice 25% H
extractor 75% P&S 0.8433 1.4728 1.4715 0.0013 +97.01 +97.05 0.04 1.31 0.38 2.59
1 50% H
Screw press 50%0 PB 0.8422 1.4724 1.4709 0.0015 +97.57 +97.60 0.03 0.92 0.30 2.02
December, 1947
10% H
Pipkin juice 50% P
extractor 40% S 0.8426 1.4725 1.4712 0.0013 +97.01 +97.06 0.05 1.63 0.33 2.18
50% H
Screw press 50% PB 0.8420 1.4723 1.4709 0.0014 +97.53 +97.60 0.07 1.34 0.48 1.77
January, 1948
Fraser Brace 50% P
extractor 50% S 0.8458 1.4733 1.4709 0.0024 +95.16 +97.12 1.96 1.08 1.45 4.81
60% S
Pipkin juice 35% P
extractor 5% H 0.8426 1.4724 1.4709 0.0015 +96.81 +96.81 0.00 1.74 0.42 1.94
50% P
Screw press 50% S 0.8416 1.4721 1.4707 I 0.0014 +97.49 +97.52 0.03 1.55 0.33 1.38
February, 1948
Fraser Brace 50% P I
extractor 50% S 0.8453 1.4734 1.4703 0.0031 +95.16 +97.12 1.96 1.08 1.50 4.93
Pipkin juice 50% P
extractor 50% S 0.8430 1.4724 1.4710 0.0014 +96.81 +97.37 0.56 1.78 0.38 2.19
45% P
45% S
Screw press 10% V 1 0.8420 1.4723 1.4710 0.0013 +97.13 +97.54 0.41 1.41 0.20 1.68





TABLE 3.-THE PHYSICAL AND CHEMICAL PROPERTIES OF COLDPRESSED ORANGE OILS PRODUCED IN FLORIDA-(Concluded).
Refrac-
Refrac- tive Optical Alde- Evapor-
Type Variety Specific tive Index Optical Rotation hyde Ester ation
of of Gravity Index of 10% Differ- Rotation of 10% Differ- Con- Con- Resi-
Extractor Fruit* 25C./25C. 20 Distillate ence 25 Distillate ence tent tent due
nD 20 D 25 % % %
nD D D
50% P I
Pipkin roll 50% S 0.8424 1.4722 1.4709 0.0013 +97.76 +97.77 0.01 1.70 0.15 1.49
March, 1948
Fraser Brace 50% P
extractor 50% S 0.8449 1.4734 1.4710 0.0024 +95.21 +96.96 1.75 1.64 0.35 3.70
Pipkin juice
extractor 100% V 0.8428 1.4723 1.4708 0.0015 +96.61 +96.96 0.35 2.04 0.08 2.08
50% P
Screw press 50% P&S 0.8421 1.4719 1.4711 0.0008 +97.04 +97.24 0.20 1.52 0.04 1.95

Pipkin roll 100% V 0.8420 1.4718 1.4708 0.0010 +97.34 +98.19 0.85 1.98 0.34 1.07
April, 1948
Fraser Brace
extractor 100% V 0.8441 1.4730 1.4713 0.0017 +96.10 +97.61 1.51 1.65 0.97 3.12
Pipkin juice J
extractor 1100% V 0.8431 1.4725 1.4712 0.0013 +96.19 +97.21 1.02 1.97 0.53 2.09

Screw press 100% V 0.8420 1.4722 1.4711 0.0011 +96.69 +97.25 0.56 1.52 0.53 1.71

Pipkin roll 100% V 0.8423 1.4721 1.4711 0.0010 +97.16 +97.52 0.36 2.02 0.39 1.31
May, 1948
Fraser Brace I
extractor 100% V I 0.8455 1 1.4733 1.4713 0.0020 +95.66 +98.10 2.44 1.45 1.50 3.99
Pipkin juice I
extractor 1100% V 0.8431 1.4723 1.4710 0.0013 +96.66 +97.83 1.17 1.77 0.91 2.36

Screw press 100% V 0.8426 1.4721 1.4712 0.0009 +97.59 +98.32 0.73 1.38 0.95 2.11

Pipkin roll 100% V 0.8425 1.4719 1.4710 0.0009 +97.73 I +98.19 0.46 1.72 1.01 1.57
H = Hamlin, PB = Parson Brown, P = Pineapple, S = Seedling, V = Valencia.







20 Florida Agricultural Experiment Stations

METHODS OF ANALYSES
The physical properties of the original oils and the 10 percent
distillates were determined by the Official and Tentative Methods
of Analysis of the Association of Official Agricultural Chemists
(1). The specific gravity was determined at 25'C./250C. and
the optical rotation at 250C. as recommended by the United
States Pharmacopoeia (38).
The aldehyde content of the oils was determined by the
hydroxylamine method, a standard procedure for which is given
by Guenther (14). The final end point for the reaction was
obtained by using a titrimeter rather than the bromphenol blue
indicator. All of the aldehyde values were calculated as de-
cylaldehyde, except those for the lime and Meyer lemon oils,
which were calculated as citral.
The method of Seeker and Kirby, as reported by Poore (35),
was used for the determination of esters. In this method the
aldehydes present are removed with hydroxylamine hydro-
chloride prior to the saponification of the esters.
The evaporation residue was determined by a method very
similar to that given by Guenther (14). A watch glass (100 mm.
in diameter) was used in place of an evaporating dish, and after
having been heated on the steam bath for the prescribed length
of time the watch glass was transferred to an oven at 1000C.
and dried for one hour.

OIL OF ORANGE
COLDPRESSED OIL OF ORANGE
The physical and chemical properties of samples of coldpressed
oil of orange, which were secured from four commercial plants
each month from October 1947 through May 1948, are presented
in Table 3. Each of the four plants used a different method
for expressing the oil. These data are also shown graphically
in Figs. 8 to 13, inclusive.
Data from the various processing plants pertaining to the
yields of oil obtained by the different methods of extraction are
presented in Table 4 and Figs. 2, 3, 5, and 7. Table 4 also shows
the relationship between the yields of coldpressed orange oils,
which were obtained by the four methods of extraction, and
all of the physical and chemical properties of the oils, except
the aldehyde content. Data for all four of the different methods
of extraction are not available for the months prior to February;








Essential Oils from Florida Citrus 21


O PIPKIN JUICE EXTRACTOR
0 SCREW PRESS
9 PIPKIN ROLL
FRASER BRACE EXTRACTOR
S0.84e ---------------------------------------------------------
S U.S.P. XIII
d 0.842
TO
o0.84 o.e4e



w 0.844

I-

0.84


0.842- -- ---- ...

OCT. NOV. DEC. JAN. FEB. MAR. APR. MAY
Fig. 8.-Specific gravity of coldpressed orange oils extracted by four
different methods during the 1947-48 season.


0 PIPKIN1 JUICE EXTRACTOR
1.474 0 SCREW PRESS

4 PIPKIN ROLL -----------------------------------------
FRASER BRACE EXTRACTOR

.4








OCT. NOV.R DEC. JAN. FEB. MAR. APR. MAY

TO
1.4 1.4737





OCT. NOV. DEC. JAN. FEB. MAR. APR. MAY
Fig. 9.-Refractive index of coldpressed orange oils extracted by four
different methods during the 1947-48 season.









22 Florida Agricultural Experiment Stations

O PIPKIN JUICE EXTRACTOR
0 SCREW PRESS
""9* PIPKIN ROLL -----------------------------
FRASER BRACE EXTRACTOR




z
2 +9r




I.I
I +9ey



+ 98"
U.S.P. XIII
NOT LESS THAN
t94*
NOT MORE THAN
*39*
.................................... ...- .. ........
.. I.. .. I -I - ----
OCT. NOV. DEC. JAN. FEB. MAR. APR. MAY
Fig. 10.-Optical rotation of coldpressed orange oils extracted by four
different methods during the 1947-48 season.

5.0 O PIPKIN JUIGE EXTRACTOR
0 SCREW PRESS
0 PIPKIN ROLL
4.0 0 FRASER BRACE EXTRACTOR







I US.P. XI
S3.0












0.0

OCT. NOV. DEC. JAN. FEB. MAR. APR. MAY
Fig. 11.-Evaporation residue of coldpressed orange oils extracted by four
different methods during the 1947-48 season.








Essential Oils from Florida Citrus 23

O PIPKIN JUICE EXTRACTOR
0 SCREW PRESS
( PIPKIN ROLL
2.0 FRASER BRACE EXTRACTOR









S1.0
0..


0. w

OCT. NOV. DEO. JAN. FEB. MAR. APR. MAY
Fig. 12.-Aldehyde content of coldpressed orange oils extracted by four
different methods during the 1947-48 season.


,. O PPKIN JUICE EXTRACTOR
SCREW PRESS
0 PIPKIN ROLL








SI-



0.5






0.5
OCT. NOV. DEC. JAN. FEB. MAR. APR. MAY
Fig. 13.-Ester content of coldpressed orange oils extracted by four
different methods during the 1947-48 season.
OC.NI-E.JN FB A.AR A
Fi.1.Etrcnetozodrse rneol xrce yfu
difrnIehdduin h 974 esn








24 Florida Agricultural Experiment Stations

therefore, they could not be used to secure average values for
comparison purposes. The data presented are average values
for the three months March, April, and May. They also were
obtained during those months when only the Valencia variety
of oranges was being processed. Figures 14, 15, and 16 present
these results in graphic form.

TABLE 4.-RELATION OF YIELD TO THE CHARACTERISTICS OF FLORIDIAN
OIL OF ORANGE.



S Method
E-- o of
.- 8 0 g Extraction
30 "0 a)

9.70 .8448 3.60 +95.66 1.4732 0.94 Fraser-Brace
extractor

7.00 .8430 2.18 +96.49 1.4724 0.51 Pipkin juice
extractor

4.90 .8422 1.92 +97.11 1.4721 0.51 Screw press

1.85 .8423 1.32 +97.41 1.4719 0.58 Pipkin roll


The relationship between the aldehyde content of expressed
oil of orange and the quantity of aqueous phase which comes
in contact with the oil during processing can be seen in Table
5 and Fig. 17. Here, also, the average values for the aldehyde
content of samples of oil produced during March, April, and
May are used. The results secured for oils extracted during

TABLE 5.-EFFECT OF QUANTITY OF AQUEOUS PHASE ON THE ALDEHYDE
CONTENT OF FLORIDIAN OIL OF ORANGE.

Aqueous Phase Aldehyde Content Method of
Gal./Gal. Oil % Extraction
12.5 1.93 Pipkin juice extractor
21.5 1.91 Pipkin roll
100.0 1.58 Fraser-Brace extractor
190.0 I 1.47 J Screw press







O SPECIFIC GRAVITY
0 EVAPORATION RESIDUE 35

S /3.0
w2

.S845 -2.5




o a.
j. .843 1.5 $
.842 -- 1.0
O I I l

I 2 3 4 5 6 7 8 9 10
YIELD- LB. OIL/TON PEEL
Fig. 14.-Relation of specific gravity and evaporation residue of coldpressed
orange oils to yield.
O OPTICAL ROTATION
0 REFRACTIVE INDEX

oo
'il.473 98.4







Fig.x and optical rotation of coldpressed
I +97*


1.472 .,96.







1.0








I-/
So
U.
1.471 I I I I I A 94*
I 2 3 4 5 6 7 8 9 10
YIELD LB.OIL/TON PEEL
Fig. 15.-Relation of refractive index and optical rotation of coldpressed
orange oils to yield.

1.0-








01-






YIELD LB.OIL/ TON PEEL
Fig. 16.-Relation of ester content of coldpressed orange oils to yield.








26 Florida Agricultural Experiment Stations

January and February by the Fraser-Brace extractor were not
included in these average values because a basic change was
made in this processing method after these samples of oil had
been obtained. Extremely large quantities of water were being
used with this extractor during January and February. In
March the amount of water used was reduced to give 100 gallons
of an aqueous phase per gallon of oil produced and the oil
extracted in that month contained 52 percent more aldehyde
than the February sample.


P .O


I.0









O 50 100 150 200
AQUEOUS PHASE= GAL./GAL. OIL

Fig. 17.--Influence of the quantity of aqueous phase which comes in
contact with the oil during processing on the aldehyde content of coldpressed
orange oils.

The analyses of samples of expressed oil of orange, extracted
during March, April, May, and June from Valencia oranges by
the Pipkin juice extractor, are given in Tables 6 and 7. Values
in Table 6 are for oil which was extracted from fruit on the
day it was harvested; the data in Table 7 refer to oil extracted
from fruit which was held in storage bins from three to five
days prior to its extraction. The differences between the av-
erage values of the properties of the oils immediately extracted
and the oils extracted from the stored fruit are presented in
Table 8. Significant differences were found only in the chemical
properties of these oils.
iC




1.0 p---- i--------i----


















properties of these oils.











TABLE 6.-PROPERTIES OF OIL OF ORANGE EXPRESSED FROM FRUIT ON THE DAY HARVESTED.

SRefrac-
Refrac- tive Optical Alde- Evapor-
Quantity Variety Specific tive Index Optical Rotation hyde Ester ation
Date of Oil of Gravity Index of 10% Differ- Rotation of 10% Differ- Con- Con- Resi-
Sampled Fruit 25C./25C. 20 Distillate ence 25 Distillate ence tent tent due
Lb. n D 20 D 25 % % %
D D

3-22-48 11,000* Valencia 0.8428 1.4723 1.4708 .0015 +96.61 +96.96 0.35 2.04 0.08 2.08

4-8-48 11,000 Valencia 0.8427 1.4725 1.4714 .0011 +96.38 +97.44 1.06 1.94 0.53 2.07

4-14-48 11,000 Valencia 0.8431 1.4725 1.4712 .0013 +96.19 +97.21 1.02 1.97 0.53 2.09

5-10-48 11,000 Valencia 0.8427 1.4722 1.4712 .0010 +97.26 +97.76 0.50 1.84 0.71 1.85

6-1-48 11,000 Valencia 0.8428 1.4719 1.4707 .0012 +97.29 +97.77 0.48 1.65 0.60 1.98

6-21-48 11,000 Valencia 0.8427 1.4719 1.4709 .0010 +96.97 +98.37 1.40 1.45 0.45 1.74

A__ ___verage 0.8428 1.4722 1.4710 .0012 +96.78 +97.58 0.80 1.82 0.48 1.97
Each 11,000 pounds of oil represents approximately 70,000 boxes of fruit.












TABLE 7.-PROPERTIES OF OIL OF ORANGE EXPRESSED FROM FRUIT STORED IN FRUIT BINS FOR THREE TO FIVE DAYS.

Refrac-
Refrac- tive Optical Alde- Evapor-
Quantity Variety Specific tive Index Optical Rotation hyde Ester ation
Date of Oil of Gravity Index of 10% Differ- Rotation of 10% Differ- Con- Con- Resi-
Sampled Fruit 25C./25C. 20 Distillate ence 25 Distillate ence tent tent due
Lb. n D 20 D 25 %
D D

3-19-48 11,000* Valencia 0.8430 1.4723 1.4708 .0015 +96.61 +96.96 0.35 1.92 0.25 2.07

4-10-48 11,000 Valencia 0.8426 1.4725 1.4710 .0015 + 96.39 +97.23 0.84 1.89 0.60 2.17

4-14-48 11,000 Valencia 0.8432 1.4723 1.4709 .0014 +96.52 +97.20 0.68 1.89 0.63 2.33

5-10-48 11,000 Valencia 0.8421 1.4722 1.4711 .0011 +96.78 +97.50 0.72 1.76 0.86 2.18

6-1-48 11,000 Valencia 0.8428 1.4720 1.4709 .0011 +96.89 +98.17 1.28 1.59 0.77 2.14

6-21-48 11,000 Valencia 0.8426 1.4719 1.4708 .0011 +97.29 +98.37 1.08 1.40 0.68 2.09

Average 0.8427 1.4722 1.4709 .0013 +96.74 +97.57 0.83 1.74 0.63 2.16

Each 11,000 pounds of oil represents approximately 70.000 boxes of fruit.








Essential Oils from Florida Citrus 29

The maximum and minimum values for the physical and chemi-
cal properties of samples of coldpressed orange oil from four
commercial plants during the 1947-48 and 1948-49 seasons are
presented in Table 9.
Relation of Yield to Properties and U. S. P. Specifications.-The
factor found to influence the physical and chemical properties
of coldpressed oil of orange to the greatest extent was the yield
of oil secured from the peel. As shown in Table 4 and Figs.
14 and 15, as the yield increased the values of the specific gravity,
evaporation residue, and refractive index also increased, but
the values of the optical rotation decreased. Thus the percentage
of the total amount of oil in the peel that is extracted deter-
mines the characteristics of the oil and, therefore, its final
quality. As the yield of oil is increased, more high-boiling,
high-molecular-weight constituents are evidently extracted; the
presence of a higher percentage of these compounds in the
oil causes a reduction in the percentage of d-limonene, resulting
in lower optical rotation values, since d-limonene is the most
optically active component in the oil.
Yield of oil obtained by the various methods of processing
varied from 1.85 lbs./ton of peel to 9.70 Ibs./ton of peel. Com-
mercial plants often have more peel than it is possible for them to
process and still obtain the maximum amount of oil recoverable
from the peel. This being the case, the plants are operated in
such a manner as to produce the maximum amount of oil on an
hourly basis. To do this they partially extract the oil from
a large quantity of peel rather than secure the maximum re-
covery of oil from a smaller quantity of peel. By operating
in this manner they may secure very low yields of oil, despite
the fact that they are capable of obtaining much higher yields
with the use of the same equipment.
The yields of oil using the Pipkin roll and screw press methods
of extraction, shown in Table 4, appear to be low when com-
pared to the yields obtained by the other methods of extraction,
but this is caused by the operation of the equipment from an
efficiency standpoint on an hourly rather than a yield basis.
Quality of the oil is influenced by the yield obtained, which
in turn is determined by operational procedure of the equipment
used and other processing techniques.
Analyses of expressed oils of orange indicate that oil pro-
duced by some manufacturing processes at certain times during
the season did not meet the U. S. P. (38) specifications, because








W
o


TABLE 8.-INFLUENCE OF STORAGE OF FRUIT, PRIOR TO EXTRACTION, ON THE PROPERTIES OF COLDPRESSED OIL OF ORANGE.
Oil Expressed Oil Expressed
from Fruit Soon from Fruit %
After Harvesting After Storage Difference Difference
(Table 6) (Table 7)

Specific gravity 25C/25C. 0.8428 0.8427 0.0001 Not significant
Refractive index n 20
Refractive index n 1.4722 1.4722 0.0000 Not significant

Refractive index 10% distillate n 1.4710 1.4709 0.0001 Not significant

Difference 0.0012 0.0013 0.0001 Not significant
Optical rotation cc 25
Optical rotation D +96.78 +96.74 0.04 Not significant

Optical rotation 10% distillate cc 25+97.58 +9.57 0.01 Not significant
D -97.58 -97.57 0.01 Not significant

Difference 0.80 0.83 0.03 Not significant S

Aldehyde content % 1.82 1.74 0.08 4.6

Ester content % 0.48 0.63 0.15 31.3

Evaporation residue % 1.97 2.16 0.19 _9.6








Essential Oils from Florida Citrus 31

yields were too low or too high. Only one method of extrac-
tion yielded oil that consistently met requirements of the U. S. P.
throughout the season. However, it is apparent that if oil is
extracted in such manner that the yield falls within a certain
range, then it will meet U. S. P. specifications.
By using data obtained during this investigation, it is possi-
ble for any processor to produce an oil meeting U. S. P. speci-
fications, provided he is willing to change his manufacturing
procedures. He may still use available equipment, operating it
in such manner that he will secure a yield of oil having properties
which are indicative of good quality. Based upon the data ac-
cumulated, it is estimated that a yield of 6.5 to 8.5 pounds of
oil per ton of peel from mid-season oranges or the extraction
of 45 to 60 percent of the total amount of oil in the peel of any
variety of fruit of good maturity will result in a coldpressed oil
of orange that will meet the specifications of the United States
Pharmacopoeia (38).
It might also be added that oil extracted about the middle of
May from Valencia oranges which had passed peak maturity
did not meet U. S. P. standards. The reason that this late-
season oil was of lower quality was that low yields of oil were
obtained with this type of fruit because the peel had become soft
and pliable, making the extraction of the oil more difficult.
Effect of Aqueous Phase of Aldehyde Content.-The flavor
quality of oil of orange is dependent upon the many constituents
of which it is composed. The aldehyde content of the oil,
although not included in the U. S. P. specifications, is indicative
of the flavoring qualities of the oil; although other constituents
are also very important from a flavor standpoint. Data in Table
5 and Fig. 17 indicate that the aldehyde content decreases as
the amount of aqueous phase which comes in contact with the
oil during processing is increased.
The average aldehyde content of the expressed oils of orange,
secured during March, April, and May from the four plants at
which material balance studies were made, varied from 1.47 to
1.93 percent. In one plant-where, at the suggestion of the
authors, the water used in the process was reduced from ex-
tremely large quantities to an amount sufficient to give 100
gallons of aqueous phase per gallon of oil produced, while other
variable factors were kept constant-the aldehyde content in-
creased from 1.08 to 1.64 percent, or 52 percent. Thus, it is
evident that to produce an orange oil of high aldehyde content,









TABLE 9.-MAXIMUM AND MINIMUM VALUES FOR THE PROPERTIES OF COLDPRESSED ORANGE OIL PRODUCED IN FLORIDA 13
DURING THE 1947-48 AND 1948-49 SEASONS.
S( Fraser-Brace Pipkin Juice
Method of Extraction All Methods Pipkin Roll Screw Press Extractor Extractor
Number of Samples Analyzed *35-63** 4-6 6 8-6 6-3 17-48
Maxi- Mini- Maxi- Mini- Maxi- Mini- Maxi- I Mini- Maxi- Mini-
mum mum mum mum mum mum mum mum mum mum

Specific gravity 25C./250C. *0.8458 0.8416 0.8425 0.8420 0.8426 0.8416 0.8458 0.8441 0.8433 0.8420
**0.8453 0.8420 0.8432 0.8420 0.8423 0.8420 0.8453 0.8443 0.8443 0.8424
Refractive index N 20 1.4734 1.4718 1.4722 1.4718 1.4724 1.4719 1.4734 1.4730 1.4729 1.4722
D 1.4743 1.4724 1.4734 1.4724 1.4733 1.4727 1.4743 1.4736 1.4737 1.4729
Refractive index of 10%
distillate N 20 1.4715 1.4703 1.4711 1.4708 1.4712 1.4707 1.4713 1.4703 1.4715 1.4707
"D 1.4727 1.4714 1.4722 1.4717 1.4723 1.4719 1.4724 1.4718 1.4727 1.4714
0.0031 0.0008 0.0013 0.0009 0.0015 0.0008 0.0031 0.0017 0.0015 0.0010
Difference 0.0019 0.0007 0.0012 0.0007 0.0012 0.0007 0.0019 0.0016 0.0015 0.0010
Optica rotation c 25 +97.761 +95.16 +97.76 +97.16 +97.59 +96.69 +96.30 +95.16 +97.57 +96.19
Dpi roton +98.05 +94.54 +98.05 +96.64 +97.80 +96.53 +96.12 +94.54 +97.55 +94.98
Optical rotation of 10% |
distillate 25 +98.70 +96.81 +98.19 +97.52 +98.32 +97.24 +98.70 +96.96 +97.89 +96.81
D +98.73 +96.49 +98.31 +97.30 +98.65 +97.81 +98.31 +97.84 +98.73 +96.49
2.44 0.00 0.85 0.01 0.73 0.03 2.44 1.51 1.30 0.00
Difference 3.70 0.14 1.28 0.14 1.41 0.60 3.70 2.05 2.00 0.57
2.04 0.92 2.02 1.70 1.55 0.92 1.65 1.08 2.04 1.17
Aldehyde content-% 1.71 0.93 1.70 1.63 1.50 1.37 1.39 0.93 1.71 1.48
1.63 0.04 1.01 0.15 0.95 0.04 1.63 0.35 1.09 0.08
Ester content-% 1.34 0.19 0.75 0.19 1.09 0.35 1.28 0.93 1.34 0.32
4.93 1.07 1.57 1.07 2.20 1.38 4.93 3.12 2.59 1.85
Evaporation residue-% 4.19 1.37 2.42 1.40 2.23 1.37 4.19 3.86 3.22 2.12
*First figure represents 1947-48 season.
"**Second figure represents 1948-49 season.








Essential Oils from Florida Citrus 33

the amount of aqueous phase allowed to come in contact with
the oil during processing should be reduced to as small a quantity
as is practical under operating conditions.
Relation of Fruit Variety to Properties.-Consideration of
Table 3 and Figs. 8, 9, and 10 shows that the oils manufactured
by any one process fell within a particular category of their
own and remained there throughout the season. The differences
in the physical properties of expressed orange oils obtained
from different varieties of fruit by any particular process were
not significant-except in the case of the Fraser Brace method
of extraction where, during the month of April, an apparently
erratic variation occurred.
The aldehyde content of coldpressed oils of orange, as can be
seen from Table 3 and Fig. 12, was highest when made from
Valencia oranges. Mixtures of Pineapple and seedling oranges
gave an oil with a lower aldehyde content, and mixtures of
Hamlin and Parson Brown varieties yielded the lowest aldehyde
content oil.
Variety of fruit apparently had very little effect on the ester
content of the orange oils. Oil of orange produced by the
Fraser Brace extractor from mid-season varieties that were
partially green in color was considerably higher in ester con-
tent than that made by the same process later in the season
from the same varieties when they were completely orange in
color, and it was also higher in esters than oils produced by
the other methods. High evaporation residue values also were
found for the oils produced by the Fraser Brace extractor.
Storage of Fruit Prior to Oil Extraction.-Results obtained in-
dicate that the length of time fruit was stored prior to the
extraction of the oil was another factor which influenced the
characteristics and quality of the oil. This is illustrated by
data presented in Tables 6, 7, and 8, which show the effect stor-
age of the fruit had upon the physical and chemical properties
of the oil.
There were no significant differences in the physical properties
of coldpressed oils of orange extracted from fruit on the same
day it was harvested and those extracted from fruit having
been stored in fruit bins for three to five days before the oils
were extracted. However, significant differences were found
in the chemical properties. The ester content of the oil from
stored fruit was 31.3 percent higher than that extracted from
fruit which had not been stored. The evaporation residue of








34 Florida Agricultural Experiment Stations

the oil from the stored fruit was 9.6 percent higher and the
aldehyde content was 4.6 percent lower.
Effect of Maturity on Properties.-In the studies of the effect
of fruit storage on oil quality, all samples of oil of orange were
from the same variety of fruit and were extracted by the same
process. Therefore, over a period of four months information
was obtained in reference to the effect of maturity on the proper-
ties of the oil. Here, again, differences were noted in the chemi-
cal characteristics rather than in the physical properties.
The aldehyde content of Valencia orange oils increased as
maturity increased, reached a maximum when extracted dur-
ing the early part of the Valencia season from fruit that just
passed the maturity standards, and then decreased after peak
maturity had been reached. The ester content of these oils was
lowest when extracted during the early part of the Valencia
season and gradually increased as the fruit became more mature.
Valencia oranges that had passed peak maturity produced an
oil with the highest ester content of any oils secured during the
year.
Effect of Yearly Variations on Properties.-Maximum and
minimum values for the properties of coldpressed orange oil
produced in Florida during the 1947-48 and 1948-49 seasons are
shown in Table 9. The 1947-48 fruit season was considered to
be a very wet year; whereas, the 1948-49 fruit season was
considered to be a very dry year, and it would be expected that
yearly variations of this kind would result in differences in the
physical and chemical characteristics of the oil.
However, only two factors were affected to any extent. These
were refractive index and aldehyde content. The values for
refractive index shown in Table 10 averaged 0.0008 of a unit
higher during the 1948-49 fruit season. Refractive index values
for one process obtaining high yields of oil exceeded the U. S. P.
standards due to this increase; whereas, the values for two
processes obtaining low yields of oil met the U. S. P. require-
ments due to this increase.
As shown in Table 11, average values for aldehyde content
of oils produced during the 1947-48 and 1948-49 fruit seasons
were 1.73 and 1.49 percent, respectively. The difference between
these two values shows a decrease of 16.1 percent in the alde-
hyde content of oil produced during the 1948-49 fruit season.
Apparently dry weather had some physiological effect on the
fruit which caused the aldehyde content of the oil to be lower.














TABLE 10.-RELATION OF YIELD TO THE CHARACTERISTICS OF COLDPRESSED ORANGE OIL PRODUCED IN FLORIDA DURING THE
1947-48 AND 1948-49 SEASONS.


Specific Evaporation Optical Refractive Ester
Yield Gravity Residue Rotation Index Content Method
lb. oil/ton Peel 256C./25C. % 25 N20 % of "
__ D N D Extraction
_1947-48 [1948-49 1947-48 1948-49 1947-48 1948-49 11947-48 1948-49 11947-48 11948-49
II I Fraser-Brace
9.70 I 0.8448 0.8448 3.60 4.04 +95.66 +95.05 1.4732 1.4739 0.94 1.08 Extractor
SI Pipkin Juice
7.00 0.8430 0.8431 2.18 2.46 +96.49 +96.16 1.4724 1.4732 j 0.51 0.77 Extractor .

4.90 1 0.8422 0.8421 1.92 1.75 +97.11 +97.07 1.4721 1.4729 0.51 0.64 Screw Press

1.85 0.8423 0.8423 1.32 2.06 +97.41 +97.61 1.4719 1.4727 0.58 0.49 Pipkin Roll







w-
cc








36 Florida Agricultural Experiment Stations

In Table 10 a correlation is shown between ester content and
yield of oil secured from the peel for the 1948-49 season. As
yield increased the values for ester content increased. This
correlation was not evident during the 1947-48 season.
Data presented in Tables 10 and 11 represent average values
for the months of March, April and May, during which time
most of the oranges processed were Valencia.

TABLE 11.-ALDEHYDE CONTENT OF COLDPRESSED ORANGE OIL PRODUCED
IN FLORIDA DURING THE 1947-48 AND 1948-49 SEASONS.

Aldehyde Content Method
%__ of
1947-48 1 1948-49 Extraction
1.93 1.60 Pipkin juice extractor
1.91 1.66 Pipkin roll
1.58 1.23 Fraser-Brace extractor
1.47 1.46 Screw press
1.73 1.49 All methods (average)


Comparison of Florida Coldpressed Orange Oil with Oils from
Other Sources.-Data presented in Table 12 shows how Florida
orange oil compares with similar types of oils from California
and various foreign countries. All of the data in these tables
for Florida oils are based on results secured during this investi-
gation. The data for the oils from other sources are those given
by Guenther (9, 10, 12) and are based upon analyses of many
samples of these oils in the laboratories of Fritzsche Brothers,
New York.
From the comparison of the properties presented in this table
it is evident that Florida citrus oils can be equal or superior
to essential oils from any other source. Further research is
being undertaken in reference to the flavoring qualities of the
essential oils produced in Florida, in order to demonstrate that
they can consistently be manufactured with high flavoring
quality.
DISTILLED OIL OF ORANGE
In Table 13 maximum and minimum values are presented for
nine samples of vacuum steam distilled orange oils, which were
secured from cannery deoilers. A comparison is made with














TABLE 12.-COMPARISON OF FLORIDIAN COLDPRESSED ORANGE OIL WITH OILS FROM OTHER SOURCES.


U.S.P. XIII Floridian Californian Italian Guinea Brazilian
Specifications Coldpressed Orange Coldpressed Coldpressed Coldpressed Coldpressed
Coldpressed Orange Orange Orange Orange
Orange Maxi- Mini- IMaxi- Mini- Maxi- Mini- Maxi- Mini- Maxi- Mini-
mum mum Average mum mum mum mum mum mum mum mum
Specific 0.842
gravity to 0.846 0.842 0.843 0.846 0.843 0.846 0.843 0.845 0.840 0.847 0.842
(25C./25C.) 0.846 _
Refractive 1.4723
index to 1.4734 1.4718 1.4724 1.4742 1.4731 1.4740 1.4729 1.4742 1.4721 1.4747 1.4723
(20C.) 1.4737
Evaporation not less
residue than 4.9 1.1 2.2 5.1 3.5 4.3 1.4 2.4 1.1 4.8 2.2
% 1.7%
I not less than
Optical +94 and not
rotation more than +99" +97.76' +95.16" +96.750 +98.330 +94o +97.17 +95.5 +980 +94 +97.87 +95.0
(25C.) in 100mm tube ___








38 Florida Agricultural Experiment Stations

California distilled orange oil. From this comparison it is evi-
dent that the values for specific gravity, refractive index, evapor-
ation residue and optical rotation are in close agreement. A
comparison between the aldehyde content of these two oils can-
not be made, since values are not available for the California
oils.

TABLE 13.-COMPARISON OF FLORIDA AND CALIFORNIA DISTILLED
ORANGE OIL.

__ Florida__ California
Maxi- Mini- [ Maxi- Min-
mum mum Average mum mum
Specific gravity 0.846 0.840 0.842 0.842 0.840
(25C./25C.) _
Refractive
de 20 1.4732 1.4715 1.4720 1.4730 1.4717
index N D

Evaporation 1.24 0.08 0.47 1.0 0.5
residue %

Optical
rotation 25 +98.560 +95.920 +97.620 +99.10 +980
rotation -D
Aldehyde
content % 2.48 1.72 1.99 -
(decyl)

The values for Florida distilled orange oil in Table 13 were
secured during the 1947-48 processing season; corresponding
values for samples of coldpressed oil may be found in Table 9.
By considering the values for coldpressed orange oil obtained
from all methods studied, it can be seen that the distilled oil
had an aldehyde content about 24 percent higher and an ester
content about 10 percent lower than the corresponding values
for the best quality coldpressed oils.
From these results it was evident that large quantities of
aldehydes were removed from the citrus juice itself by the de-
oilers during commercial canning operations. Also, it is indi-
cated that removal of oil from the juice by the deoilers results
in fractionation of the peel oil originally present; so that the
small quantity of oil which remains in the canned juice will
have different characteristics from either expressed or distilled
oils. Oil distilled from citrus fruit juice would seemingly have
better flavoring qualities than oil obtained by steam distillation.














TABLE 14.-CHARACTERISTICS OF COLDPRESSED GRAPEFRUIT OIL PREPARED IN PILOT PLANT FROM VARIOUS VARIETIES
OF FRUIT.
Co

Refrac- 1
Refrac- tive Optical Alde-
Variety tive Index Optical Rotation Dif- hyde Ester Evapor-
of Specific Index of 10% Dif- Rotation of 10% ference Con- Con- ation
Fruit Gravity 20 Distillate ference 25 Distillate tent tent Residue
25"C./25C. n D 20 aD 25 % % %


Duncan ................ 0.8560 1.4773 1.4716 0.0057 +90.25 +97.23 6.98 1.30 3.59 10.50

Marsh Seedless .... 0.8570 1.4772 1.4715 0.0063 +88.61 +97.23 8.62 1.58 3.55 10.64
-5
Thompson Pink .... 0.8558 1.4773 1.4715 0.0058 +90.04 +96.03 3.99 1.46 3.47 10.29

Ruby Red ............. 0.8556 1.4771 1.4714 0.0057 +89.38 +97.03 7.65 1.54 4.41 9.73
Foster Pink .......... 0.8588 1.4779 1.4711 0.0068 +86.74 +96.23 9.49 1.66 3.70 13.46







CO








40 Florida Agricultural Experiment Stations

OIL OF GRAPEFRUIT AND SHADDOCK
During recent years the demand for Florida coldpressed grape-
fruit oil has decreased. Large essential oil houses have com-
plained that they have been unable to obtain grapefruit oil
which would meet the flavor requirements as based upon oils
obtained in the past. Because sufficient information concern-
ing the character of coldpressed grapefruit oils produced in Flor-
ida has been lacking, the following information is presented to
show the properties of oil made from different varieties of fruit
by the same process, as well as to show the analyses of oils
made by commercial plants.

COLDPRESSED OIL OF GRAPEFRUIT
Experimental Samples.-The physical and chemical charac-
teristics of grapefruit oil expressed from five different varieties
of grapefruit are presented in Table 14. These samples repre-
sent pure grapefruit oil from known varieties of grapefruit pre-
pared in the Citrus Experiment Station pilot plant using an
experimental model of the Fraser-Brace grater.
Selection of varieties was made to include the common types
of grapefruit. Since readers may not be familiar with their
genetic relationship, it is given in Fig. 18. Shaddock or pum-
melo is listed as the progenitor of grapefruit. However, there
is some doubt in regard to this relationship, which is discussed
further in the section on coldpressed oil of shaddock.
Variety of grapefruit was thought to be a factor which might
be affecting quality of oil, since in recent years manufacturers
in some instances have processed mixed varieties of fruit. How-
ever, no significant differences were found in analyses of oils
secured from different varieties of grapefruit, as shown in Table
14.
Commercial Samples.-Four samples of coldpressed grapefruit
oil were secured from four plants, each of which was using a
different method for the extraction of oil from the peel. These
samples were taken from lots of oil ranging from 3,500 to 11,000
pounds, which represented the production for approximately one
year.
The physical and chemical properties of these samples of
coldpressed grapefruit oil are presented in Table 15. The grape-
fruit oil samples expressed by the Pipkin roll were slightly con-
taminated with orange oil. This often occurs in some com-
mercial processes, since the over-sized oranges usually go to









Essential Oils from Florida Citrus 41

the grapefruit juice extractors. This results in a very small
amount of orange peel being mixed with the grapefruit peel.
In general, the coldpressed grapefruit oil produced in Flor-
ida during past years has been very slightly contaminated with
orange oil. It is quite probable that original standards were
based on samples which were contaminated with orange oil.
However, during recent years methods of processing have been
greatly improved and present-day production represents pure

Citrus Grandis


SHADDOCK
or
PMMELO


I

Citrus Paradisi



SEEIED GRAPBFRUIT
Thought to be a Sport or
Variant of the Shaddock




MARSH SEEDLESS VARIETY FOSTER PIK VARIETY
A Sport or Variant (Seeded)
of a Seeded Type
Sport of Walters



TBCMPSON PIK VARIETY
Sport of Marsh Seedless




RUBY RED UAD OTHER RED HEATED VARIETIES
(Seedless)
Sport of Thpomson Pink


Fig. 18.-Genetic relationships of the common types of grapefruit.








42 Florida Agricultural Experiment Stations

grapefruit oil. Therefore, it seems evident that this factor is
responsible for its rejection in some cases.

TABLE 15.-PHYSICAL AND CHEMICAL PROPERTIES OF COLDPRESSED
GRAPEFRUIT OIL PRODUCED COMMERCIALLY.
Fraser- Pipkin
Method of Extraction Brace Juice Screw Roll
Extractor Extractor Press Pipkin
Specific gravity
25"C./25C. 0.8560 0.8556 0.8505 0.8537
Refractive
20 1.4773 1.4774 1.4755 1.4767
index n D
Refractive index of
10% dis-
tillae 20 1.4716 1.4712 1.4713 1.4714
tillate n D

Difference 0.0057 0.0062 0.0042 0.0053
Optical
rotation 25 +90.25 +91.03 +92.83 +92.35
rotation a D
Optical rotation of
10% dis-
tillate a 2 +97.23 +97.05 +97.03 +96.63
tillate a

Difference 6.98 6.02 4.20 4.28.
Aldehyde I
content % 1.30 1.24 1.46 1.53

Ester content-% 3.59 4.66 3.68 4.38
Evaporation
residue % 10.50 8.62 5.77 7.72

COLDPRESSED OIL OF SHADDOCK
It has been commonly accepted that the grapefruit was a
sport from the shaddock and probably for this reason oil of
shaddock has commonly been included with oil of grapefruit.
Actually, this relationship of shaddock to grapefruit has not
been established, but rather surmised, since the grapefruit more
nearly resembled the shaddock. The two might not be related
or the grapefruit might be a natural cross between shaddock and
orange.
In connection with these experiments, a sample of oil was
made from the true shaddock and the constants were deter-
mined. These data will be found in Table 16, where they are
compared with data on oils from both seedy and seedless grape-
fruit and orange oil. It will be noted that both optical rotation
and aldehyde content of oil of shaddock are considerably lower








Essential Oils from Florida Citrus 43

than those of oil of grapefruit. In the case of both ester content
and evaporation residue, the figures for oil of shaddock are high,
with orange oils having the lowest values. It would thus appear
that in several respects oil of grapefruit appears to be inter-
mediate between oil of orange and oil of shaddock.

TABLE 16.-A COMPARISON OF THE CHARACTERISTICS OF TYPICAL SAMPLES
OF CITRUS OILS EXPRESSED FROM DIFFERENT VARIETIES OF CITRUS BY
THE SAME METHOD OF EXTRACTION.

Grapefruit Valencia
Variety of Fruit Shaddock Marsh Orange
Seedless Duncan
Specific gravity
25C./25C. 0.858 0.857 0.856 0.844
Refractive index n
Refractive index n 1.4779 1.4778 1.4773 1.4730
20 I
Optical rotation a D +81.14 +88.61 +90.25 +96.10

Aldehyde content % 0.46 1.58 1.30 1.65

Ester content % 4.22 3.55 3.59 0.97

Evaporation residue % 12.99 10.64 10.50 3.12

The authors have not found in the literature any data relative
to pure oil of shaddock. In view of the data in Table 16, it
might be advisable to consider eliminating the synonymy, since
oil of shaddock might at some time become an article of com-
merce.

TABLE 17.-MAXIMUM AND MINIMUM VALUES FOR THE PHYSICAL AND
CHEMICAL PROPERTIES OF DISTILLED GRAPEFRUIT OIL.

Maximum Minimum

Specific, gravity 25C./250C. 0.8539 0.8415

Refractive index N 20 1.4746 1.4714
D

Optical rotation cc D +96.50 +91.50

Aldehyde content % 4.06 2.30

Ester content--% 2.52 0.08

Evaporation residue %1 3.66 0.19







44 Florida Agricultural Experiment Stations

DISTILLED OIL OF GRAPEFRUIT
In Table 17 maximum and minimum values are included for
nine samples of vacuum steam distilled oil obtained in the de-
oiling of grapefruit juice. It is interesting to note that, when
compared with the coldpressed oils, the distilled oils are much
higher in aldehyde content. Distilled grapefruit oils will gen-
erally run 90 percent higher in aldehydes and 60 percent lower
in esters than the expressed oils.

OIL OF PERSIAN SEEDLESS LIME
The complete utilization of the peel from Persian 5 limes
(Citrus aurantifolia Swingle) canned in Florida involves the
recovery of expressed and distilled oils. The Persian or seedless
lime, which represents the bulk of the present commercial crop
SPersian lime synonymous with Tahiti lime.
Fig. 19.-Installation for the manufacture of Florida expressed and
distilled oil of lime.


I









Essential Oils from Florida Citrus 45


in Florida, should not be confused with the Key or seedy lime
produced in the southern part of the state. The Persian lime
is approximately twice the size of the Key (or West Indian)
lime. Today most of the limes grown in Florida are sold on
the fresh fruit market. However, surplus and cull fruit are
available for juice and oil recovery. Cull fruit is of good quality
but unsuitable for shipment as fresh fruit, due to size and grade
restrictions.
The primary products resulting from processing of this fruit
are single strength and concentrated juice. The oil found in
the peel of the fruit is the first product recovered from the




LIME PEEL
FROM

__I__
ROLL -PRESS EFFLUENT

PULP SR*--------SCREEN
PRESSED PEEL

PRIZE STORAGE
NEAT MEAT TANK
CHOPPER CHOPPER

MASHED EFFLUENT CENTRIFUGE
CHOPPED CENTRIFUE 16000 IcoooR.P.M.
PEEL
SCOLD PRESSED
LIME OIL
COLD SlTORAGE

J__, --! __ A WINTERED
OUTLET C OL PRESSED
WOODEN COPPER T LIME OIL
STORAGE C-ONDENSE
TANK
STAINLESS
STEEL
STILL STEAM DISTILLED
TI LIME OIL

LIVE STEAM


JACKET STILL SLOP
TO
DUMP TRUCK



Fig. 20.-Flow sheet for the manufacture of Florida expressed and
distilled oil of lime.













TABLE 18.-PHYSICAL AND CHEMICAL PROPERTIES OF COLDPRESSED PERSIAN LIME OILS IN FLORIDA DURING THE 1948 SEASON.

SRefrac-
Refrac- tive Optical Alde-
Type Specific tive Index Optical Rotation Differ- hyde Evapora-
Date of Gravity Index of 10% Differ- Rotation of 10% ence Content Ester ation
Extractor 20C. 20 Distillate ence 20 Distillate % Content Residue
/20oC. nD 20 aD 20 (Citral) % %
nD D D

7-15-48 Pipkin Roll 0.8810 1.4847 1.4730 0.0017 +40.60 +47.60 7.00 5.52 7.98 13.36
7-24-48 Pipkin Roll 0.8798 1.4842 1.4730 0.0112 +41.00 +48.20 7.20 4.86 7.42 12.95
8- 6-48 Pipkin Roll 0.8799 1.4845 1.4729 0.0116 +41.52 +49.24 7.72 4.95 4.95 14.03
8- 9-48 Pipkin Roll 0.8823 1.4853 1.4731 0.0122 +41.80 +49.24 7.44 5.35 8.13 13.44
8-13-48 Pipkin Roll 0.8816 1.4851 1.4730 0.0121 +39.76 +48.84 9.08 3.66 8.08 14.67
8-20-48 Pipkin Roll 0.8821 1.4853 1.4730 0.0123 +38.60 +48.48 9.88 5.19 8.03 13.97
9- 4-48 Pipkin Roll 0.8780 1.4839 1.4729 0.0110 +41.12 +48.72 7.60 5.40 7.46 12.39
9-11-48 Pipkin Roll 0.8811 1.4846 1.4730 0.0116 +42.12 +49.92 7.80 6.14 7.11 12.71
9-28-48 Pipkin Roll 0.8807 1.4847 1.4732 0.0115 +44.08 +52.20 8.12 5.65 7.66 13.04
10- 4-48 Fraser-Brace 0.8792 1.4849 1.4732 0.0117 +54.60 4.46 7.28 13.23
10-13-48 Fraser-Brace 0.8786 1.4844 1.4734 0.0110 +51.80 5.20 7.11 12.62
10-16-48 Fraser-Brace 0.8796 1.4847 1.4725 0.0122 +50.52 5.17 6.78 13.04
10-23-48 Fraser-Brace 0.8789 1.4841 1.4724 0.0117 +49.32 4.74 7.02 13.24
10-16-48 Pipkin Roll 0.8777 1.4837 1.4731 0.0106 +43.36 +51.12 7.76 5.50 6.80 11.88
10-23-48 Pipkin Roll 0.8769 1.4834 1.4731 0.0103 +43.00 +49.20 6.20 5.83 7.15 11.01

*-Too dark to read in 25 mm. tube.







Essential Oils from Florida Citrus 47

cannery refuse and both coldpressed and distilled lime oils
are obtained. The coldpressed oil is considered superior to the
distilled oil but, because of the relatively high price of the dis-
tilled oil, it becomes economically feasible to recover both types
of oil.
Lime oil was expressed with two different types of commercial
equipment in Florida during the 1948 season. These were the
Pipkin roll and Fraser-Brace extractor. Figure 19 shows an
installation for the manufacture of expressed and distilled lime
oil, and the flow diagram for this commercial process is given in
Fig. 20.
A total of 26 samples of coldpressed and distilled Persian
lime oils was obtained. Fifteen of the samples were coldpressed
oil secured from two plants, each of which used a different meth-
od for the extraction of the oil from the peel. These samples
were taken once a week from lots of oil which represented the
production for approximately one week. These samples repre-
sented coldpressed oil which was expressed from 11,232 standard
field boxes of Persian limes.
After the removal of some coldpressed oil from the peel, the
peel was then steam distilled to obtain the distilled lime oil.
Eleven distilled samples were secured and analyzed by methods
previously described.

COLDPRESSED OIL OF LIME
The physical and chemical properties of samples of cold-
pressed lime oil, which were obtained from two commercial
plants from July through October 1948, are presented in Table
18. The factor found to influence the physical and chemical
properties of coldpressed Persian lime oil to the greatest extent
was the yield of oil secured from the fruit.
Yield data on the two methods of manufacture were deter-
mined and are as follows: (1) Pipkin roll 0.4 lb. oil/ton fruit
and (2) Fraser-Brace extractor 1.22 lb. oil/ton fruit. The Fraser-
Brace extractor obtained three times more expressed oil than
the Pipkin roll. Oil manufactured by the Fraser-Brace extractor
was so dark in color that optical rotation determinations could
not be made in a 25 mm. tube. The average values for two
composite samples of oil made by each of two processes from
October 13 to 16 and October 20 to 23 from different lots of
fruit are presented in Table 19.








48 Florida Agricultural Experiment Stations

TABLE 19.-A COMPARISON BETWEEN THE PHYSICAL AND CHEMICAL
PROPERTIES OF COLDPRESSED PERSIAN LIME OIL MANUFACTURED BY
Two METHODS OF EXTRACTION.
Fraser- Pipkin
Method of Extraction Brace Roll
Difference
Yield of Oil/Ton of Fruit 1.22 lb. 0.40 lb.__Differen

Specific gravity 20C./20C. 0.8793 0.8773 0.0020
Refractive index N 0.0009
D 1.4844 1.4835 0.0009
Refractive
Refractive N20 1.4724 1.4731 0.0007
index of 10% distillate N 14724 1471 00007

Difference 0.0120 0.0104 0.0016
20 I
Optical rotation cc D-- + .18 -
Optical rotation
of 10% distillate c 20 +49.94 +50.16 0.24

Difference 6.98 -

Aldehyde content (citral) % 4.95 5.66 0.71

Ester content % 6.90 6.98 0.08

Evaporation residue % 13.14 11.44 1.70

Relation of Yield to Properties.-It can be seen from Table
19 that the higher the yield of oil obtained from the fruit, the
higher the value for specific gravity, refractive index, and evapor-
ation residue. As the yield of oil is increased, more high-boiling,
high-molecular-weight constituents are evidently extracted, and
the presence of a larger percentage of these compounds in the
oil results in higher values for specific gravity, refractive index
and evaporation residue.
The total quantity of recoverable oil in whole limes for this
season ranged between 0.20 and 0.22 percent. This value is on
the basis of 11,232 standard field boxes of limes.
Effect of Aqueous Phase on Aldehyde Content.-It was im-
possible to make a material balance on the aqueous phase for
each of the two processes, due to irregularities in processing
operations. However, a significantly larger quantity of water
was used in the Fraser-Brace process than in the Pipkin roll
process. Data in Table 19 indicate that the aldehyde content
of oil produced by the Fraser-Brace process was lower than
that for the Pipkin roll process. This would indicate that alde-








Essential Oils from Florida Citrus 49

hyde content decreases as amount of aqueous phase which comes
in contact with the oil during processing is increased.
As shown in Table 18, relatively small variations in com-
position of coldpressed Persian lime oil were noted throughout
the processing season. As the season progressed, limes were
continually becoming mature, resulting in a mixture of fully
mature and partially mature fruit. This factor probably ac-
counts for the properties of the oil remaining fairly constant.
However, the last two samples taken, representing the last two
weeks' run of the season, gave significant differences for specific
gravity and evaporation residue. In each case these values were
lower; whereas, all the other values remained practically the
same.

TABLE 20.-FLORIDA COLDPRESSED PERSIAN LIME OIL COMPARED WITH
COLDPRESSED WEST INDIAN LIME OIL.

Persian Lime West Indian Lime
_Maximum I Minimum Average I Maximum I Minimum
Specific gravity 0.882 0.877 0.880 0.886 0.878
200C./20C. __ (15-C.) (15-C.)
Refractive index
20"C. 1.4853 1.4834 I 1.4845 1.4860 1.4800

Optical rotation +44.08 +38.600 +41.54"
(20oC.) (20C.) (200C.) +400 +350
Aldehyde con-
tent % 6.1 3.7 5.2 8.5 4.5
(as citral)
Ester content % 8.2 6.8 7.5 -
Evaporation I
residue % 14.7 11.0 13.0 13.5 10.0

Comparison of Coldpressed Oils.-Florida coldpressed Persian
lime oil is compared with coldpressed West Indian 6 lime oil in
Table 20. The values shown in the table for West Indian lime
oil are those given by Guenther (11). These data show that
there is no significant difference in the values for specific gravity,
refractive index, and evaporation residue. However, the Persian
lime oil has a higher value for optical rotation and a lower value
for aldehyde content than those for West Indian lime oil. Maxi-
mum and minimum values for Florida Persian lime oil as given
in Table 20 are considered to represent a high quality oil. Since

" These small seedy limes are known by various names: Mexican, Do-
minican, and Key limes.








50 Florida Agricultural Experiment Stations

these two types of oil are made from two distinct varieties of
limes, a fair comparison of their qualities cannot be made.

DISTILLED OIL OF LIME
The properties of steam distilled Persian lime oil are given
in Table 21. These samples were obtained from peel which was
first expressed to obtain some coldpressed oil, and subsequently
steam distilled to produce the distilled oil of lime. In Table 22
a comparison is given of two samples of distilled Persian lime
oil made from the same lot of fruit. One sample was made
by the Pipkin roll process while the other was made by the
Fraser-Brace process. In the Pipkin roll process the peel, after
passing through the Pipkin roll, is crushed and mashed in an
Enterprise meat chopper, water added, and then distilled. In
the Fraser-Brace process the effluent from the centrifuge is
distilled to obtain the oil.

TABLE 21.-PHYSICAL AND CHEMICAL PROPERTIES OF DISTILLED PERSIAN
LIME OILS PRODUCED IN FLORIDA DURING THE 1948 SEASON.
Specific Refrac- Optical Aldehyde Ester Evapor-
Gravity tive Index Rotation Content Content ation
Date 20oC. n20 20 % % Residue
/20'C. D D (Citral) %
7-31-48 0.8556 1.4745 +50.52 1.61 2.41 0.18
8- 6-48 0.8579 1.4751 +46.84 2.32 3.49 0.88
8- 9-48 0.8562 1.4746 +47.24 2.71 3.10 0.42
8-13-48 0.8572 1.4749 +47.44 1.77 3.04 1.23
8-20-48 0.8561 1.4743 +48.08 1.76 2.54 0.29
9- 4-48 0.8560 1.4748 +48.92 2.31 2.63 0.48
9-11-48 0.8569 1.4748 +48.92 2.27 2.24 1.17
9-28-48 0.8596 1.4757 +47.60 2.37 2.49 1.70
10-15-48 0.8546 1.4747 +52.60 4.58 1.75 0.25
10-16-48 0.8565 1.4749 +49.60 2.27 2.38 0.83
10-23-48 0.8555 1.4749 +50.00 2.34 2.15 0.70


From Table 22 it can be seen that there is a considerable
difference in these two oils. The oil obtained from the Fraser-
Brace process had a lower value for specific gravity and a higher
value for optical rotation. The aldehyde content was 101 per-
cent higher. The ester content and the evaporation residue
were 36 and 232 percent higher respectively for the Pipkin roll
process. The loss of aldehydes which occurred in the Pipkin
roll process was considered to be due to the degradation of the
aldehydes by steam in the presence of citric acid. The still
charge in the Pipkin roll process was much more acidic than
that in the Fraser-Brace process. Guenther (11) has shown









Essential Oils from Florida Citrus 51

that the combination of heat and acid on lime oil has a marked
effect on the aldehyde content of the oil.

TABLE 22.-A COMPARISON OF Two SAMPLES OF DISTILLED PERSIAN
LIME OIL MADE BY Two PROCESSES.

Process Fraser-Brace Pipkin Roll Difference

Specific gravity 20C./20C. 0.8546 0.8565 0.0019
20
Refractive index n D 1.4747 1.4749 0.0002

Optical rotation a D52.60 +49.60 3.

Aldehyde content (citral) % 4.58 2.27 2.31

Ester content % 1.75 2.38 0.63

Evaporation residue % 0.25 0.83 0.58

Effect of Coldpressing the Peel Prior to Distillation.-In Table
23 a comparison is made of the physical and chemical properties
of oils distilled from fruit that had been coldpressed and from
fruit that had not been coldpressed. Each of these samples was
prepared by the Pipkin roll process.
As can be seen from the data in Table 23, there are no signifi-
cant differences in the values for specific gravity, refractive in-
dex, optical rotation, and aldehyde content. However, the oil
made from peel that had not been coldpressed had higher values
for ester content and evaporation residue.

TABLE 23.-DISTILLED PERSIAN LIME OIL MADE FROM PEEL WHICH WAS
COLDPRESSED PRIOR TO DISTILLATION AS COMPARED WITH OIL MADE
FROM PEEL WHICH WAS NOT COLDPRESSED PRIOR TO DISTILLATION.
Peel Was Peel Was not
Coldpressed Coldpressed
Prior to Prior to Difference
Distillation Distillation

Specific gravity 20C./20'C. 0.8569 0.8560 0.0009
20
Refractive index n 20
D 1.4748 1.4748 0.0000
Optical rotation a +48.92 +48.92 0.00
Aldehyde content
(citral) % 2.27 2.31 0.04

Ester content % 2.24 2.63 0.39

Evaporation residue- % 0.48 1.17 0.69








52 Florida Agricultural Experiment Stations

Comparison of the Distilled Oils.-Table 24 gives a comparison
of Florida distilled Persian lime oil with distilled West Indian
lime oil. The physical and chemical properties shown in the
table for West Indian lime oil are those given by Guenther (11).
It will be noted that the Persian lime oil produced in Florida
has higher values for optical rotation and aldehyde content;
whereas, the values for specific gravity and refractive index
are lower than those of the West Indian lime oil.

TABLE 24.-FLORIDA DISTILLED PERSIAN LIME OIL COMPARED WITH
DISTILLED WEST INDIAN LIME OIL.

Persian Lime West Indian Lime
______Maximum | Minimum Average IMaximum Minimum
Specific gravity
(20C./20"C.) 0.860 0.855 0.857 0.868 0.862
Refractive index j (15C.) (15C.)
(20C.) 1.4757 1.4743 1.4749 1.4770 1.4750
+52.60 +46.84 +48.91
Optical rotation (20C.) (20C.) (20C.) +46 j +350
Aldehyde con-
tent % 4.6 1.6 2.4 1.5 0.5
(as citral)
Ester
content % 3.5 1.8 2.6 -
Evaporation I
residue % 1.7 0.3 0.7 -

Guenther (11) states that a high grade lime oil should have a
specific gravity of not less than 0.864 at 150C. It can be seen
from the data in Table 24, that the Persian lime oil produced in
Florida is quite different from the West Indian lime oil and can-
not be expected to meet the same requirements, since it is
made from a different variety of lime. The maximum and mini-
mum values for Florida lime oil as given in Table 24 are con-
sidered to represent a high quality Persian lime oil. Probably
since these two types of oil are made from two distinct varieties
of limes, they should have different quality standards.
The maximum and minimum values for the properties of
expressed and steam distilled Persian lime oil are listed in Table
25. Also included in this table are results from the analysis of
one sample of steam distilled oil from 25 boxes of Meyer lemon.
Properties of Meyer lemon oil indicate that it is predominantly
lemon in character, although the Meyer lemon is commonly be-
lieved to be a natural hybrid.








TABLE 25.-CHARACTERISTICS OF ESSENTIAL OILS SECURED FROM PERSIAN LIME AND MEYER LEMON.

Type of Oil Persian Lime Meyer Lemon

Number of samples 15 11 1
Steam c
Coldpressed Steam Distilled Distilled M
Maximum Minimum Maximum Minimum

Specific gravity 200C./20C. 0.8823 0.8769 0.8596 0.8546 0.8555
Refractive index N 20 I;t
RefractiveD 1.4853 1.4834 1.4757 1.4743 1.4740

Refractive index of 10% distillate N D 1.4734 1.4724 -
Difference______1_________43_142_____0.4734_0.010__ ______-_____-___

Difference 0.0123 0.0103 -
20
Optical rotation cc 2 +44.08 I +38.60 +52.60 +46.84 +56.00.
20
Optical rotation of 10% distillate cc 2D +54.60 +47.60 -

Difference 9.88 6.20

Aldehyde content % 6.14 3.66 4.58 1.61 1.19
I I
Ester content % 8.13 4.95 | 3.49 1.75 2.45

Evaporation residue % 14.67 11.01 1.70 0.18 0.16

eo







54 Florida Agricultural Experiment Stations

OIL OF TANGERINE

In time past the processing of tangerines to obtain the oil
was accomplished by crushing the whole fruit. Today, tan-
gerines are processed in a manner that much resembles that for
oranges. The fruit is processed mainly for its juice, which is
packed out as a single-strength or concentrated product. Oil of
tangerine is recovered by both vacuum de-oiling the juice and
processing the peel by conventional oil extraction methods. Pro-
duction of this oil is very limited and is confined to the Dancy
variety of tangerine which predominates in Florida. The oil
produced from the peel of this fruit has a deep orange color, a
pleasing aroma, and a flavor which resembles that of the Man-
darin oils. The physiochemical properties, however, are slightly
different from those of Mandarin oils.

TABLE 26.-MAXIMUM AND MINIMUM VALUES FOR THE PHYSICAL AND
CHEMICAL PROPERTIES OF TANGERINE OIL.

Type of Oil Coldpressed De-Oiler
Maximum I Minimum

Specific gravity 25C./25C. 0.8474 0.8454 0.8407
20
Refractive index n D J 1.4744 1.4734 1.4720
Refractive index
of 10% distillate n 14726 14711

Difference 0.0023 0.0018 -
Optical rotation a 91.18 +90.0 +93.67
D 1 +91.18 4+90.09 +93.67
Optical rotation
of 10% distillate a D2 +94.21 +92.68

Difference 4.12 1.50
Aldehyde content % 1.08 0.95 1.24
Ester content % 1.44 0.34 0.25
Evaporation residue % 4.83 4.04 0.20

In Table 26 maximum and minimum values are presented for
three samples of coldpressed tangerine oils representing lots of
oil ranging from 500 to 11,000 pounds of oil, and one sample of a
35-pound lot of vacuum steam distilled oil obtained in the de-
oiling of the juice.








Essential Oils from Florida Citrus 55

CITRUS STRIPPER OIL

Stripper oil is obtained as a by-product from the manufacture
of citrus molasses. Citrus press liquor contains 0.20 to 0.50
percent peel oil and, since this oil steam distills readily, 60 to
80 percent of the oil present in the liquor can be recovered by
flashing from 2400F. to atmospheric conditions. Florida has
a potential production of over one million pounds per year,
based on the quantity of citrus molasses made in previous years.
Not all processors are equipped to recover this oil, so yearly
production is somewhat less. Stripper oil is usually a mixture of
citrus oils, since the press liquor is obtained most often from a
mixture of orange and grapefruit peel. It frequently possesses
a fine citrus oil character, marred only by a slight distilled char-
acter, and contains very little of the waxy material ordinarily
present in expressed citrus oils. Table 27 presents the physical
and chemical properties of this oil.

TABLE 27.-PHYSICAL AND CHEMICAL PROPERTIES OF 10 SAMPLES OF
STRIPPER OIL.

Stripper Oil Maximum Minimum

Specific gravity 25C./25C. 0.8433 0.8398
20
Refractive index n 1.4721 1.4713
Optical rotation a 5+98.90 +95.5

Aldehyde content %7 1.50 0.47
Ester content %l 2.46 0.07
Evaporation residue %0.79 1 0.03

Since stripper oil contains over 95 percent of d-limonene, it
is considered one of the purest sources for this mono-cyclic ter-
pene. A synthetic spearmint oil flavor, 1-carvone, already has
been manufactured from this oil. Considerable quantities of
citrus stripper oil are bought yearly by the paint and varnish
industry, where it is recognized as an excellent antiskinning
agent. Other uses for this oil are as an ingredient of clear
plastics, as a base for soap perfumes, and as a penetrating oil.








56 Florida Agricultural Experiment Stations

EVALUATION OF CITRUS OILS
Orange oil, widely used in flavoring a variety of food products,
is subject to air oxidation during storage. This constitutes a
serious problem to the essential oil industry. These oxidative
changes that occur in orange oil are accelerated by heat, mois-
ture, or a catalyst; they lead to off-flavors and off-odors that are
like oxidized turpentine in character, and are referred to as
"terpeney" by the essential oil trade. The exclusion of air from
containers of orange oil by replacement with carbon dioxide
has considerable merit in preventing the onset of these changes;
however, the susceptibility of an oil to oxidative changes is an
important criterion in selecting a desirable flavoring oil.
In the past, organoleptic tests were used to evaluate the sta-
bility of an oil as such, or when used in combination with other
materials. This same technique was used in studies to deter-
mine how well an oil will stand up in products subjected to
different conditions of temperature and storage. Recently at-
tempts were made by Kesterson and McDuff (24) and by Proctor
and Kenyon (36) to assign relative stability values to oils by
measurement of oxygen uptake. The longer the time required
for absorption of a certain quantity of oxygen the more stable
the oil was toward oxidative spoilage. One complication, how-
ever, was the problem of determining true oxygen consumption.
It was demonstrated that citrus peel oils evolved gas and that
manometric methods for measuring oxygen uptake must take
this fact into account. An improved manometric method (25,
26) was therefore developed and used in the following detailed
studies of orange oil.

EXPERIMENTAL METHOD
The improved technique used for evaluating the oils, employ-
ing the Warburg respirometer, is as follows: Prior to being put
through the procedure the oil sample is dried with anhydrous
sodium sulfate. A 1-g. sample of oil is then placed in a 17.5-ml.
cell, (Aminco 5-202), flushed with dry U. S. P. oxygen for a
period of 15 minutes, and then immersed in a constant-tempera-
ture water bath at 400C. -t 0.30C. (1040F.). The cell is allowed
to reach equilibrium conditions before the run is started and is
then shaken at the rate of 80 cycles per minute for the entire
run. One ml. of Ascarite is placed in the side arm of the cell to
remove the carbon dioxide and water vapor that are evolved.








Essential Oils from Florida Citrus 57

Throughout the entire experiment the respirometer is operated
at constant volume. The drop in pressure caused by the uptake
of oxygen is read, when possible, at intervals of one hour in
order to follow the oxygen consumption. Comparison of stability
is made by considering the time required for each sample to take

900



800



700



So600
0

"500



S400



-j 300
o Screw Press
"._ 0 Pipkin Roll
200- e Pipkin Juice Extractor
( Fraser Brace Extractor

100



0 10 20 30 40 50 60
Time in Hours
Fig. 21.-Microliters of gas evolved from Florida coldpressed Valencia
orange oil exposed to an atmosphere of nitrogen at 40* C. (oil extracted
May 1949).








58 Florida Agricultural Experiment Stations

up 1,200 microliters (1.2 ml.) of oxygen. At this point the
samples are terpeney in aroma and lighter in color.

DISCUSSION OF EXPERIMENTAL METHOD
In the early uses of the method it was not recognized that
citrus oils liberated gas and thus no provision was incorporated
for removing the evolved gases. In the method described, the
improved procedure makes use of Ascarite, a sodium hydrate
asbestos absorbent, to remove these evolved gases. The evolu-
tion of gas was first noticed when the more stable orange oils
in comparison tests showed initial positive pressure readings
while exposed to an atmosphere of oxygen at 400C. It was
surmised that all orange oils were liberating gas, but that some
were absorbing oxygen faster than the gas was being evolved.
To substantiate this idea orange oils were studied under an
inert atmosphere of nitrogen, using a modified Dixon-Keilin flask.
By the use of specific absorbents, the gas evolved was found to
be carbon dioxide and water vapor. The amount of evolved gas
was measured and the quantities are shown in Fig. 21.
TABLE 28.-TYPICAL ANALYSES OF FLORIDA COLDPRESSED VALENCIA ORANGE
OIL EXTRACTED BY FOUR DIFFERENT COMMERCIAL PROCESSES.
Pipkin1 Fraser-
Pipkin Screw Juice Brace
Roll Press Extractor Extractor
Specific gravity 25C./250 C. 0.8423 0.8420 0.8431 0.8441
20
Refractive index N D1.4721 1.4722 1.4725 1.4730
Refractive index
10% distillate 20 1.4711 1.4711 1.4712 1.4713
10% distillate N D

Difference 0.0010 0.0011 0.0013 0.0017
Optical rotation c +97.16 +96.69 +96.19 +96.10
Optical rotation 2
10% distillate o 25 +97.52 +97.25 +97.21 +97.61
10% distillate 0' D

Difference 0.36 0.56 1.02 1.51

Aldehyde content % 2.02 1.52 1.97 1.65

Ester content % 0.39 0.53 0.53 0.97

Evaporation residue % 1.31 1.71 2.09 3.12
Yield
Ib. oil/ton peel 1.85 4.90 7.00 9.70
1 Synonymous with the Food Machinery Rotary Juice Extractor.







Essential Oils from Florida Citrus 59

EVALUATION OF FLORIDA COLDPRESSED ORANGE OIL
This study of Florida oils was conducted on samples of cold-
pressed orange oil extracted by four different commercial pro-
cesses, typical analyses for which are shown in Table 28. These
were all Valencia orange oils that had been dried over anhydrous
sodium sulfate.
The data presented are values for samples obtained during the
month of April 1948 that were taken from lots of oil ranging from
500 to 11,000 pounds, representing one week's production. Table
28 also shows the relationship between the yield of oil obtained
by the four methods of extraction and the physical and chemical
properties of the oils. The factor found to influence the physical
and chemical properties of coldpressed Valencia orange oil to the
greatest extent was the yield of oil secured from the peel.
Oxygen uptake was determined for the four samples described
in Table 28; as the investigation continued, three additional sets
of oil samples were studied in an identical manner. Thus, oxygen
uptake was determined for a total of 16 freshly expressed Va-
lencia orange oils representing four extraction procedures and
four different dates, April 1948, May 1948, April 1949, and May
1949. Figure 22 graphically shows the rate of oxygen uptake
in microliters for Florida Valencia orange oil extracted in May
1949. The other three sets of samples had similar curves, which
are not shown for the sake of brevity but are compared in Table
29.

TABLE 29.-RELATIVE STABILITY FACTORS FOR FLORIDA ORANGE OIL
SAMPLES BASED ON 1,200 MICROLITERS OXYGEN UPTAKE AT 400 C.

Method of Date of Extraction Yield
Extraction April I May IApril I May lb. Oil/Ton Peel
1948 1948 1949 1949
Screw press 1.0 1.0 1.1 1.0 4.90
Pipkin roll 1.3 1.2 1.0 1.1 1.85
Pipkin juice
extractor 2.3 1.5 1.8 1.9 7.00
Fraser-Brace
extractor 6.9 2.8 3.3 3.2 9.70

Comparison of stability was made by considering the time
required for each sample to take up 1,200 microliters of oxygen.
By taking as unity the time required for any sample to consume
this amount of oxygen, ratios were calculated which can be used








60 Florida Agricultural Experiment Stations

as relative stability factors. Table 29 presents the relative sta-
bility factors thus obtained for the 16 oil samples. Each of the
oil samples studied became lighter in color and terpeney in aroma
after absorbing 1,200 microliters of oxygen. The yield of oil
extracted by each method is given to show its influence on sta-
bility. It seems apparent from this study that high-yield oils
are more stable than low-yield oils.

1500






1200



a
U)

900


C

0
600-

0



300-
S0 Screw Press
4 // 0 Pipkin Roll
e Pipkin Juice Extractor
) Fraser Brace Extractor

0 25 50 75 100 125
Time in Hours

Fig. 22.-Microliters of oxygen uptake of Florida coldpressed Valencia
orange oil exposed to an atmosphere of oxygen at 400 C. (oil extracted
May 1949).








Essential Oils from Florida Citrus 61

If we consider the three types of extractors-Pipkin roll, Pipkin
juice extractor and Fraser-Brace extractor-which extract the
oil primarily from the exterior surface tissues of the fruit, then
there is a direct correlation of yield with stability. Oil extracted
by the screw press is generally considered to be inferior, but a
higher yield of oil is obtained than when the Pipkin roll is used.
In the former method tapered screws press the crushed peel
against a perforated screen, thereby squeezing out the oil.
It is postulated that in this process the albedo of the fruit may
absorb a naturally occurring anti-oxidant from the oil, thus low-
ering its stability. To further substantiate this postulation, a
high yield oil of good quality and stability was treated with
activated carbon. The stability of the carbon-treated oil was
considerably reduced. This indicates that the carbon may have
removed some naturally occurring anti-oxidant, thereby decreas-
ing the oxidative stability of the oil.
In further consideration of the data presented in Table 29, it
can be seen that in general the oils produced during the 1949
season were more stable toward oxidative spoilage. Considering,
for example, the oils manufactured by the Pipkin juice extractor
for the 1948 season, samples produced during April and May
required 16 and 36 hours respectively for the consumption of
1,200 microliters of oxygen; whereas, the 1949 season samples
produced during April and May required 65 and 67 hours, re-
spectively, for the same oxygen uptake. Apparently seasonal
variations have some physiological effect on the fruit which in-
fluences the keeping quality of the oil as related to oxidative sta-
bility.
Since essential oil houses do not generally have information
relative to the yield of oil, it seems probable that some physical or
chemical characteristic of freshly expressed orange oil might be
used as a criterion for oxidative stability. Although the proper-
ties of the oil are related to yield, as shown by Table 28, con-
siderably more work would be required in order to determine
that property which is most indicative of this relationship.
In the course of this investigation Florida oils were also placed
under an atmosphere of hydrogen and it was observed that gas
was evolved. These oils apparently underwent a chemical change
but no apparent differences developed in the color or aroma of
the oils. Although no explanation is offered at this time for the
strange behavior of these oils when heated in an atmosphere of
hydrogen, the data on gas evolution obtained is presented in
Fig. 23 as a matter of record.








62 Florida Agricultural Experiment Stations

This study of orange oil under atmospheres of oxygen, hydro-
gen, and nitrogen gases further indicated that inert or hydrogen
atmospheres are not detrimental to the flavor of the oil; whereas,
oxidizing atmospheres are responsible for the off-flavors which
develop.

900


800


700


| 600-
o


| 500


2 400-

0
"- 300-
S* Screw Press
0 Pipkin Roll
200 e Pipkin Juice Extractor
9 Fraser Brace Extractor

100



0 10 20 30 40 50 60 70 80 90
Time in Hours
Fig. 23.-Microliters of gas evolved from Florida coldpressed Valencia
orange oil exposed to an atmosphere of hydrogen at 40* C. (104 F.).

EVALUATION OF CALIFORNIA COLDPRESSED ORANGE OIL
The California oils used in these experiments were freshly
expressed good quality Valencia orange oils extracted by two








Essential Oils from Florida Citrus 63

different commercial processes. The physical and chemical char-
acteristics of these oils are shown in Table 30.

TABLE 30.-ANALYSES OF CALIFORNIA COLDPRESSED VALENCIA ORANGE
OIL EXTRACTED BY TWO DIFFERENT COMMERCIAL PROCESSES.
Pipkin
Method of Extraction Juice Citromat
Extractor

Specific gravity 25C./25C. 0.8442 0.8445
20
Refractive index N 1.4725 1.47
D 1.4725 1.4731
Refractive index 10% distillate N 201.4711 1.471

Difference 0.0014 0.0018
Optical rotation cc+96.25 96.67

Optical rotation 10% distillate cc 25 1
D 1+98.32 +99.70

Difference 2.07 3.03

Aldehyde content %1 1.54 0.44

Evaporation residue % L 3.52 1 4.73

To determine if the California oils differed from the Florida
oils in oxidative stability, oxygen uptake was determined for the
oil samples identified in Table 30. Results of this study, pre-
sented graphically in Fig. 24, show that the California oils gave
results similar to the Florida oils (Table 31). At 1,200 micro-
liters oxygen uptake the California oil samples were terpeney
in aroma.

TABLE 31.-TIME REQUIRED FOR A ONE-GRAM SAMPLE OF OIL TO ABSORB
1,200 MICROLITERS OF OXYGEN.

Type Oil Florida California
Pipkin Pipkin
Method of Extraction Juice Juice
Extractor Extractor
Extraction Date Hours Hours

April, 1948 16
May, 1948 36 -
April, 1949 65
May, 1949 67 -
August, 1950 38








64 Florida Agricultural Experiment Stations


1500


e Pipkin Juice Extractor
Citromat


1200

CL
E
0
C,,



E
C 900
C


O



j 600
o
'C







o

6.

0
300 -


I






0 10 20 30 40 50 60
Time in Hours
Fig. 24.-Microliters of oxygen uptake of California Valencia orange
oil exposed to an atmosphere of oxygen at 400 C. (oil extracted August
1950).








Essential Oils from Florida Citrus 65

ANTI-OXIDANTS FOR ORANGE OIL
Since orange oils are especially susceptible to oxidative changes
when used in certain types of food products, stabilizing agents are
added to the oil to prevent development of off-flavors in the
finished product. These stabilizing agents or inhibitors are
usually called anti-oxidants. Thus anti-oxidants may be defined
as chemical agents or compounds which stabilize and preserve by
retarding oxidation and the development of off-flavors.
Lakritz (27), using anti-oxidizing agents for expressed oil of
orange, found that benzyl p-hydroxybenzoate in concentrations
of 0.02 to 0.10 percent was not entirely satisfactory. Hydro-
quinone in the same concentrations gave excellent results, even
in the lowest concentrations. Wheat-germ oil used alone was
not as good as hydroquinone, while a mixture of wheat-germ oil
and hydroquinone gave the best results. A sample containing
this mixture retained its flavor without change of color after
seven months' storage.
In addition to effective inhibitory action, there are several other
factors which must be considered when the use of an anti-oxidant
is contemplated. According to Riemenschneider and Ault (37),
these factors are:
(a) No harmful physiological effect, even in quantities con-
siderably larger than those likely to be used and even when in-
gested over a long period of time.
(b) Be sufficiently soluble in the product in question to facili-
tate its us; the greater the solubility the more advantageous
its use.
(c) Impart no objectionable odor, color, or flavor, even after
storage.
(d) Be stable under whatever processing conditions it must be
subjected to.
(e) Should be relatively inexpensive and available in large
quantities.
Kesterson and McDuff (24) investigated 10 anti-oxidants in
coldpressed Valencia oil by organoleptic test. Each anti-oxidant
was investigated singly and in paired combination in amounts
giving a total anti-oxidant concentration of 0.1 percent. Of the
10 anti-oxidants tested-ethyl caffeate, citric acid, ascorbic acid,
alpha tocopherol, isothymol, nordihydroguaiaretic acid, as well
as four experimental anti-oxidants furnished by private labora-
tories-alpha tocopherol was found to be the most effective.







66 Florida Agricultural Experiment Stations

Kenyon and Proctor (18) studied the effect of five anti-oxi-
dants on orange oil by the Warburg method of following rate of
oxygen uptake in a respirometer. When these anti-oxidants
were added in amounts of 0.05 percent by weight to samples of
fresh orange oil, they found alpha tocopherol and nordihydro-
guaiaretic acid offered the most promise. Both propyl gallate
and ethyl gallate were less effective, while guaiacol, although
effective, was not recommended because of its strong character-
istic odor and its possible toxicity.
The deterioration of orange oil stored at 1450F. as an emulsion
and with various stabilizers was measured by Flores and Morse
(5). By determining the amount of peroxides formed, they
judged nordihydroguaiaretic acid and propyl gallate superior
to vanillin and ethyl vanillin in protecting orange oil against
oxidative deterioration.
Although some of the best anti-oxidants mentioned can prob-
ably still be improved upon, it is important for those dealing with
citrus oils to realize that considerable protection can be achieved
with anti-oxidants.
SUMMARY
Commercial methods of production of essential oils from Flor-
ida citrus have been studied and compared. The physical and
chemical properties of over 400 samples of coldpressed and dis-
tilled oils of orange, grapefruit, tangerine and lime have been
determined. Data were also obtained for shaddock, Meyer lemon
and stripper oils. Coldpressed and distilled oils of orange and
grapefruit were found to have very large differences in their
aldehyde and ester contents.
Fruit variety, degree of maturity, seasonal variations, and
storage of fruit prior to extraction were found to be factors
which affected the chemical and physical properties of expressed
oil of orange.
The properties of coldpressed grapefruit oils extracted from
Duncan, Marsh Seedless, Thompson Pink, Ruby Red and Foster
Pink varieties by the same process have been determined and
presented.
Quality of citrus peel oils, as indicated by their physical and
chemical characteristics, is determined by the yield of oil ob-
tained in any commercial process, regardless of type of extrac-
tion equipment used. It is also determined by the quantity of
aqueous phase that comes in contact with the oil during pro-








Essential Oils from Florida Citrus 67

cessing, since the aldehyde content of the oil is largely deter-
mined by this factor.
A method for evaluating and comparing the oxidative sta-
bility of citrus oils has been presented and discussed. The
stability or keeping quality of orange oil was found to be cor-
related with the quantity of oil extracted from the peel. Anti-
oxidants tend to stabilize orange oil against oxidative off-flavors.
Of 10 anti-oxidants studied, alpha tocopherol was found to be
most effective.
The use of proper processing methods results in the produc-
tion of essential oils in Florida which are of the highest quality
and which consistently meet the specifications of the United
States Pharmacopoeia. When manufactured carefully, Florida
citrus oils are equal or superior in quality to essential oils from
any other sources.

ACKNOWLEDGMENTS
Acknowledgments are made to the commercial processors and
manufacturers in Florida whose earnest cooperation contributed
much to the success of this work. Coldpressed oil samples used
in this, study were obtained from Essential Oil Producers, Inc.,
Dunedin; Pasco Packing Company, Dade City; Florida Citrus Oil
Company, Bartow; and Fraser Brace Engineering Company,
Tampa. The distilled oils were obtained from Florida Citrus
Canners Cooperative, Lake Wales; Wm. P. McDonald Corpora-
tion, Auburndale; Floridagold Citrus Corporation, Lake Alfred;
Dr. P. Phillips Canning Company, Orlando; and Essential Oil
Producers, Inc., Dunedin. The stripper oils were furnished by
the Florida Molasses Corporation, Lake Alfred; Adams Packing
Association, Auburndale; Florida Citrus Canners Cooperative,
Lake Wales; and Pasco Packing Company, Dade City.

LITERATURE CITED
1. ASSOCIATION OF OFFICIAL AGRICULTURAL CHEMISTS. Official and tenta-
tive methods of analysis. 6th Ed., 932 pp. 1945. Washington, D. C.
2. ATKINS, C. D., E. WIEDERHOLD, and J. L. HEID. The recovery of flavor-
ing oil from Persian limes-preliminary experiments. The Fruit
Products Jour. and Am. Food Manufacturer 23: 10: 306-308. 1944.
3. BARTHOLOMEW, E. T., and W. B. SINCLAIR. The factors influencing the
volatile oil content of the peel of immature and mature oranges.
Plant Physiol. 21: 3: 319-331. 1946.








Essential Oils from Florida Citrus 67

cessing, since the aldehyde content of the oil is largely deter-
mined by this factor.
A method for evaluating and comparing the oxidative sta-
bility of citrus oils has been presented and discussed. The
stability or keeping quality of orange oil was found to be cor-
related with the quantity of oil extracted from the peel. Anti-
oxidants tend to stabilize orange oil against oxidative off-flavors.
Of 10 anti-oxidants studied, alpha tocopherol was found to be
most effective.
The use of proper processing methods results in the produc-
tion of essential oils in Florida which are of the highest quality
and which consistently meet the specifications of the United
States Pharmacopoeia. When manufactured carefully, Florida
citrus oils are equal or superior in quality to essential oils from
any other sources.

ACKNOWLEDGMENTS
Acknowledgments are made to the commercial processors and
manufacturers in Florida whose earnest cooperation contributed
much to the success of this work. Coldpressed oil samples used
in this, study were obtained from Essential Oil Producers, Inc.,
Dunedin; Pasco Packing Company, Dade City; Florida Citrus Oil
Company, Bartow; and Fraser Brace Engineering Company,
Tampa. The distilled oils were obtained from Florida Citrus
Canners Cooperative, Lake Wales; Wm. P. McDonald Corpora-
tion, Auburndale; Floridagold Citrus Corporation, Lake Alfred;
Dr. P. Phillips Canning Company, Orlando; and Essential Oil
Producers, Inc., Dunedin. The stripper oils were furnished by
the Florida Molasses Corporation, Lake Alfred; Adams Packing
Association, Auburndale; Florida Citrus Canners Cooperative,
Lake Wales; and Pasco Packing Company, Dade City.

LITERATURE CITED
1. ASSOCIATION OF OFFICIAL AGRICULTURAL CHEMISTS. Official and tenta-
tive methods of analysis. 6th Ed., 932 pp. 1945. Washington, D. C.
2. ATKINS, C. D., E. WIEDERHOLD, and J. L. HEID. The recovery of flavor-
ing oil from Persian limes-preliminary experiments. The Fruit
Products Jour. and Am. Food Manufacturer 23: 10: 306-308. 1944.
3. BARTHOLOMEW, E. T., and W. B. SINCLAIR. The factors influencing the
volatile oil content of the peel of immature and mature oranges.
Plant Physiol. 21: 3: 319-331. 1946.









68 Florida Agricultural Experiment Stations

4. DE VILLIERS, F. J. Citrus by-products research: orange oil. Farming
in S. Africa. 4: 515-516, 529. 1930.
5. FLORES, HECTOR, and ROY E. MORSE. Deterioration of orange oil. Food
Technology. 6: 1: 6-8. 1952.
6. FLORIDA CITRUS MUTUAL. Annual statistical report 1950-51 season.
November 1951.
7. FOOTE, P. A., and R. Z. GELPI Florida volatile oils. IV. Sweet orange.
Jour. Am. Pharm. Assoc. 32: 6: 145-148. 1943.
8. GILDEMEISTER, E., and F. HOFFMAN. Die Aetherischen Oele. 3rd Ed.
Vols. I, II, and III. 1928-1931. Leipzig.
9. GUENTHER, E. California citrus oils. Amer. Perf. Ess. Oil Rev. May,
June, July, Aug. 1937. Reprint, 15 pp.
10. GUENTHER, E. Sketches from French Guinea and French Guinea sweet
orange oil. Amer. Perf. Ess. Oil Rev. Sept., Oct., Nov., and Dec.
1941 and Jan. 1942. Reprint 19 pp.
11. GUENTHER, E. The production of oil of limes. Amer. Perf. Ess. Oil
Rev. Nov. and Dec. 1942 and Jan., Feb., March and April 1943.
Reprint 19 pp.

12. GUENTHER, E. Brazilian sweet orange oil. Food Ind. 16: 898-902,
939-940. 1944.

13. GUENTHER, E. Mandarin and tangerine oils. Food Ind. 16: 979-982,
1021-1022. 1944.

14. GUENTHER, E. The essential oils. Vol. I, II, III, IV, V, VI. D. Van
Nostrand Co., Inc.

15. GUENTHER, E. Citrus oils and their methods of extraction. Food
Packer. 29: 10, 33-35. 1948.

16. GUENTHER, E., and E. E. LANGENAU. An investigation of the chemical
constituents of distilled lime oil. Jour. Am. Chem. Soc. 65: 959-963.
1943.

17. HOOD, S. C. Relative oil yield of Florida oranges. Ind. Eng. Chem. 8:
709-711. 1916.

18. KENYON, E. M., and B. E. PROCTOR. Effect of antioxidants on orange
oil. Food Research 16: 5: 365-371. 1951.

19. KESTERSON, J. W., and O. R. McDuFF. Physical and chemical char-
acteristics of Floridian coldpressed oil of orange (1947-48 season).
Proc. Fla. State Hort. Soc. 61: 212-222. 1949. Also published, Cit.
Ind. 30: 9: 7-9. 1949.

20. KESTERSON, J. W. A two year survey of Florida coldpressed oil of
orange. Proc. Fla. State Hort. Soc. 62: 160-162. 1949. Also pub-
lished, Cit. Ind. 31: 4: 10-11. 1950.








Essential Oils from Florida Citrus 69

21. KESTERSON, J. W. Florida coldpressed grapefruit oil. Amer. Perf. and
Ess. Oil Rev. 55: 1: 29-31. 1950.

22. KESTERSON, J. W. Florida Persian seedless lime oil. Amer. Perf. and
Ess. Oil Rev. 56: 2: 125-128, 161. 1950.
23. KESTERSON, J. W. Florida coldpressed orange oil. Amer. Perf. and
Ess. Oil Rev. 56: 5: 373-376. 1950.
24. KESTERSON, J. W., and 0. R. MCDUPF. Anti-oxidant studies. Amer.
Perf. and Ess. Oil Rev. 54: 10: 285-287. 1949.
25. KESTERSON, J. W., and R. HENDRICKSON. An improved manometric
technique for evaluating the oxidative stability of coldpressed orange
oil. Food Technology 5: 6: 220-222. 1951.
26. KESTERSON, J W., and R. HENDRICKSON. Oxidative stability of range
oil as related to method of extraction. Amer. Perf. and Ess. Oil
Rev. 57: 6: 441-444. 1951.
27. LAKRITZ, WILLIAM. Lemon and orange oil preservation. Manufactur-
ing Confectioner. 23: 9: 18-19. 1943.
28. MARKLEY, K. S., E. K. NELSON, and M. S. SHERMAN. Some wax-like
constituents from expressed oil from the peel of Florida grape-
fruit. Jour. Biol. Chem. 118: 433-441. 1937.
29. MOORE, E. L., C. D. ATKINS and E. WIEDERHOLD. A progress report on
Persian limes. Citrus Ind. 29: 6: 5-6. 1948.
30. NELSON, E. K. Florida tangerine oil. Amer. Perf. Ess. Oil Rev.
Sept. 1934.
31. NELSON, E. K., and H. H. MOTTERN. Florida grapefruit oil. Ind. Eng.
Chem. 26: 634-637. 1934.

32. NELSON, E. K., and H. H. MOTTERN. The occurrence of citral in Flor-
ida Valencia orange oil. Jour. Am. Chem. Soc. 56: 1238-1239. 1931.

33. PERRY, E. J. The chemistry of essential oils and artificial perfumes.
2nd Ed., 546 pp. 1908. Scott, Greenwood and Son.

34. PIPKIN, W. Method and machine for extracting oil from the peels of
citrus fruit. U. S. Patent No. 2,004,056. June 4, 1935.

35. POORE, H. D. Analyses and composition of California lemon and orange
oils. U. S. Dept. Agr. Tech. Bul. 241: 1-30. 1932.

36. PROCTOR, B. E., and E. M. KENYON. Objective evaluation of odor de-
terioration in orange oil. Food Technology 3: 387. 1949.

37. RIEMENSCHNEIDER, R. W., and WALDO C. AULT. How to evaluate and
improve the stability of fatty foods. Food Ind. 16: 892-894, 936,
939. 1944.

38. UNITED STATES PHARMACOPOEIA. 13th revision, 957 pp. 1947. Mack
Publishing Company.








70 Florida Agricultural Experiment Stations

39. VON LOESECKE, H. W., and G. N. PULLEY. Physical characteristics of
Florida orange oil produced during 1937-38 season. Fruit Products
Jour. 18: 228-230, 249, 251. 1939.
40. WINTON, A. L., and K. B. WINTON. The structure and composition
of foods. Vol. 2, p. 904. 1935. John Wiley and Sons, Inc.





University of Florida Home Page
© 2004 - 2010 University of Florida George A. Smathers Libraries.
All rights reserved.

Acceptable Use, Copyright, and Disclaimer Statement
Last updated October 10, 2010 - - mvs