Front Cover
 Board of control and station...
 Experimental procedures and...
 Discussion of resutls
 Literature cited
 Historic note

Group Title: Bulletin - Agricultural Experiment Station. University of Florida ; 469
Title: Florida citrus molasses
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00089242/00001
 Material Information
Title: Florida citrus molasses clarification of citrus press liquor
Series Title: Bulletin University of Florida. Agricultural Experiment Station
Physical Description: 24 p. : ill. ; 23 cm.
Language: English
Creator: Hendrickson, Rudolph
Publisher: University of Florida Agricultural Experiment Station
Place of Publication: Gainesville Fla
Publication Date: 1950
Subject: Citrus fruit industry -- By-products -- Florida   ( lcsh )
Molasses as feed   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
Bibliography: Includes bibliographical references (p. 24).
Statement of Responsibility: by R. Hendrickson.
General Note: Cover title.
General Note: "A contribution from the Citrus Experiment Station."
 Record Information
Bibliographic ID: UF00089242
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 18267354

Table of Contents
    Front Cover
        Page 1
    Board of control and station staff
        Page 2
        Page 3
        Page 4
        Page 5
    Experimental procedures and resutls
        Page 6
        Page 7
        Page 8
        Page 9
        Page 10
        Page 11
        Page 12
        Page 13
        Page 14
    Discussion of resutls
        Page 15
        Page 16
        Page 17
        Page 18
        Page 19
        Page 20
        Page 21
        Page 22
        Page 23
    Literature cited
        Page 24
    Historic note
        Page 25
Full Text

Bulletin 469

April, 1950

(A Contribution from the Citrus Experiment Station)

Florida Citrus Molasses

Clarification of Citrus Press Liquor

Assistant Chemist, Citrus Experiment Station


Single copies free to Florida residents upon request to


Frank M. Harris, Chairman, St. Petersburg
N. B. Jordan, Quincy
Hollis Rinehart, Miami
Eli H. Fink, Jacksonville
George J. White, Sr., Mount Dora
W. F. Powers, Secretary, Tallahassee

J. Hillis Miller, Ph.D., President3
J. Wayne Reitz, Ph.D., Provost for
Willard M. Fifield, M.S., Director
L. O. Gratz, Ph.D., Asst. Dir., Research
Geo. F. Baughman, M.S., Business Manager'
Claranelle Alderman, Accountant3


C. V. Noble, Ph.D., Agr. Economist '3
H. G. Hamilton, Ph.D., Mktg. Economist
R. E. L. Greene, Ph.D., Agr. Economist
Zach Savage, M.S.A., Associate
A. H. Spurlock, M.S.A., Associate
D. E. Alleger, M.S., Associate
D. L. Brooke, M.S.A., Associate
M. R. Godwin, Ph.D., Associate
H. W. Little, M.S., Assistant
Tallmadge Bergen, B.S., Assistant
D. C. Kimmel, Ph.D., Assistant
Orlando, Florida (Cooperative USDA)
G. Norman Rose, B.S., Asso. A"rr.
J. C. Townsend, Jr., B.S.A., Agr.
J. B. Owens, B.S.A., Agr. Statistician2
J. F. Steffens, Jr., B.S.A., Agr. Statistician2

Frazier Rogers, M.S.A., Agr. Engineer '
J. M. Johnson, B.S.A.E., Asso. Agr.
J. M. Myers, B.S., Asso. Agr. Engineer
R. E. Choate, B.S.A.E., Asst. Agr. Engineer3
A. M. Pettis, B.S.A.E., Asst. Agr. Engineer2 '

Fred. H. Hull, Ph. D., Agronomist'
G. E. Ritchey, M.S., Agronomist2
G. B. Killinger. Ph.D., Agronomist'
H. C. Harris, Ph.D., Agronomist 4
R. W. Bledsoe, Ph.D., Agronomist
W. A. Carver, Ph.D., Associate
Darrel D. Morey, Ph.D., Associate
Fred A. Clark, B.S., Assistant
Myron C. Grennell, B.S.A.E., Assistant
M. N. Gist, Collaborator2

R. S. Glasscock, Ph.D., An. Husbandman'
J. E. Pace, M.S., Asst. An. Husbandman
S. John Folks, B.S.A., Asst. An. Hush.
T. J. Cunha, Ph.D., Asso. An. Husbandman:
G. K. Davis, Ph.D., Animal Nutritionist'
R. L. Shirley, Ph.D., Biochemist
Katherine Boney, B.S., Asst. Chem.

E. L. Fouts, Ph.D., Dairy Technologist' "
R. B. Becker, Ph.D., Dairy Husbandman'
S. P. Marshall, Ph.D., Asso. Dairy Husb.3
W. A. Krienke, M.S., Asso. in Dairy Mfs'
P. T. Dix Arnold, M.S.A., Asst. Dairy Husb.2
L. E. Mull. M.S., Asst. in Dairy Tech.
Howard Wilkowski, Ph.D., Asst. Dairy Tech.

J. Francis Cooper, M.S.A., Editor'
Clyde Beale, A.B.J., Associate Editor3

A. N. Tissot, Ph.D., Entomologist'
L. C. Kuitert, Ph.D., Associate
F. A. Robinson, M.S., Asst. Apiculturist
H. E. Bratley, M.S.A., Assistant

Ouida D. Abbott, Ph.D., Home Econ.'
R. B. French, Ph.D., Biochemist

G. H. Blackmon, M.S.A., Horticulturist'
F. S. Jamison, Ph.D., Horticulturist'
Albert P. Lorz, Ph.D., Asso. Hort.
H. M. Reed, B.S., Chem., Veg. Processing
R. K. Showalter, M.S., Asso. Hort.
R. A. Dennison, Ph.D., Asso. Hort.
R. H. Sharpe, M.S., Asso. Hort.
R. J. Wilmot, M.S.A., Asst. Hort.
R. D. Dickey, M.S.A., Asst. Hort.
Victor F. Nettles, Ph.D., Asst. Hort.
L. H. Halsey, M.S.A., Asst. Hort.
C. D. Hall, Ph.D., Asst. Hort.
F. S. Lagasse, Ph.D., Asso. Hort.2

Ida Keeling Cresap, Librarian

W. B. T;sdale, Ph.D., Plant Pathologist''
Phares Decker, Ph.D., Plant Pathologist
Erdman West, M.S., Mycologist and Botanist
Howard N. Miler, Ph.D., Asso. Plant Path.
Lillian E. Arnold, M.S., Asst. Botanist
Robert W. Earhart. Ph.D. Plant Path.2
C. W. Anderson, Ph.D., Asst. Plant Path.

N. R. Mehrhof, M.Aer., Poultry Husb.' 3
J. C. Driggers, Ph.D., Asst. Poultry Husb.'

F. B. Smith, Ph.D., Microbiologist '
Gaylord M. Volk, Ph.D., Chemist
J. R. Henderson, M.S.A., Soil Technologist'
J. R. Neller, Ph.D., Soils Chemist
Nathan Gammon, Jr.. Ph.D., Soils Chemist
R. A. Carrigan, Ph.D., Biochemist3
Ralph G. Leighty, B.S., Asso. Soil Surveyor2
Geo. D. Thornton, Ph.D., Asso.
H. W. Winsor, B.S.A., Assistant Chemist
R. E. Caldwell, M.S.A., Asst. Chemist'
V. W. Carlisle, B.S., Asst. Soil Surveyor
W. L. Pritchett, M.S., Asst. Chemist'
James H. Walker, M.S.A., Asst. Soil
Walter J. Friedmann, M.S.A., Asst.
O. E. Cruz, B.S.A., Asst. Soil Surveyor

D. A. Sanders, D.V.M., Veterinarian'
M. W. Emmel, D.V.M., Veterinarian'
C. F. Simpson, D.V.M., Asso. Veterinarian
L. E. Swanson, D.V.M.. Parasitologist
Glenn Van Ness, D.V.M., Asso. Poultry
G. E. Batte, D.V.M., Asso. Parasitologist


J. D. Warner, M.S., Vice-Director in Charge
R. R. Kincaid, Ph.D., Plant Pathologist
L. G. Thompson, Ph.D., Soils Chemist
W. C. Rhoads, M.S., Entomologist
W. H. Chapman, M.S., Asso. Agron.
Frank S. Baker, Jr., B.S., Asst. An. Husb.
Mobile Unit, Monticello
R. W. Wallace, B.S., Associate Agronomist
Mobile Unit, Marianna
R. W. Lipscomb, M.S., Associate Agronomist
Mobile Unit, Chipley
J. B. White, B.S.A., Associate Agronomist
Mobile Unit, Pensacola
R. L. Smith, M.S., Associate Agronomist


A. F. Camp, Ph.D., Vice-Director in Charge
W. L. Thompson, B.S., Entomologist
J. T. Griffiths, Ph.D., Asso. Entomologist
R. F. Suit, Ph.D., Plant Pathologist
E. P. Ducharme. Ph.D., Asso. Plant Path.4
R. K. Voorbees, Ph.D., Asso. Horticulturist
C. R. Stearns, Jr., B.S.A., Asso. Chemist
J. W. Sites. M.S.A., Horticulturist
H. 0. Sterling, B.S., Asst. Horticulturist
H. J. Reitz, Ph.D.. Asso. Horticulturist
Francine Fisher, M S., Asst. Plant Path.
I. W. Wander, Ph.D., Soils Chemist.
A. E. Willson, B.S.A., Asso. Biochemist
J. W. Kesterson, M.S., Asso. Chemist
R. N. Hendrickson, B.S., Asst. Chemist
Wallace T. Long, M.S.A., Asst. Hort.
J. C. Bowers, M.S., Asst. Chemist
D. S. Prosser, Jr., B.S., Asst. Horticulturist
R. W. Olsen, B.S., Biochemist
F. W. Wenzel, Jr., Ph.D., Supervisory Chem.
Alvin H. Rouse, M.S., Asso. Chemist
H. D. Merwin, Ph.D., Asso. Chemist
H. W. Ford, Ph.D., Asst. Hort.
L. W. Faville, Ph.D., Asst. Chemist
L. C. Knorr, Ph.D., Asso. Histologist
W. T. Long, M.S.A., Asst. Horticulturist
R. M. Pratt, B.S., Asso. Ent. Path.


R V. Allison, Ph.D.. Vice-Director in Charge
F. D. Stevens, B.S., Sugarcane Agronomist
Thomas Bregger, Ph.D., Sugarcane
J. W. Randolph, M.S., Agricultural Engineer
W. T. Forsee, Jr., Ph.D., Chemist
R. W. Kidder, M.S., Asso. Animal Husb.
T. C. Erwin, Assistant Chemist
Roy A. Bair, Ph.D., Agronomist
C. C. Seale, Asso. Agronomist
N. C. layslip, B.S.A., Asso. Entomologist
E. H. Wolf, Ph.D., Asst. Horticulturist
W. H. Thames, M.S., Asrt. Entomologist
W. N. Stoner, Ph.D., Asst. Plant Path.
W. A. Hills, M.S., Asso. Horticulturist
W. G. Genung, B.S.A.. Asst. Entomologist
C. J. D'Angio, A.B., Asst. Chemist
D. W. Smith, B.S., Asst. Chemist
W. D. Hogan, M.S., Asst. Plant Pathologist
Daniel W. Beardsley, B.S., Asst. An. Hush.
W. D. Hogan, M.S., Asst. Plant Path.
K. A. Harris, B.S.A., Asst. Agr. Engineer
David B. Gibb, M. E., Fiber Technologist

Ceo D. Ruehle, Ph.D., Vice-Dir. in Charge
D. 0. Wolfenbarger, Ph.D., Entomologist
Francis B. Lincoln, Ph.D., Horticulturist
Milton Cobin, B.S., Asso. Horticulturist
Robt. A. Conover, Ph.D., Asso. Plant Path.
John L. Malcolm, Ph.D., Asso. Soils Chemist
R. W. Harkness, Ph.D., Asst. Chemist

William Jackson, B.S.A., Animal Husband-
man in Charge2

W. G. Kirk, Ph.D.. Vice-Director in Charge
E. M. Hodges, Ph.D., Agronomist
D. W. Jones, B.S., Asst. Soil Technologist'
E. M. Kelly, B.S.A., Asst. An. Husb.

R. W. Ruprecht, Ph.D., Vice-Dir. in Charge
J. W. Wilson, Se.D., Entomologist
P. J. Westgate, Ph.D., Asso. Hort.
Ben. F. Whitner, Jr.,B.S.A., Asst.Hort.

C. E. Hutton, Ph.D., Agronomist'
H. W. Lundy, B.S.A., Associate Agronomist


G. K. Parris, Ph.D., Plant Path. in Charge
C. C. Helms, Jr., B.S., Asst. Agronomist

Plant City
A. N. Brooks, Ph.D., Plant Pathologist

A. H. Eddins, Ph.D., Plant Path. in Charge
E. N. McCubbin, Ph.D., Horticulturist

A. M. Phillips, B.S., Asso. Entomologist2
John R. Large, M.S., Asso. Plant Path.

J. R. Beckenbach, Ph.D., Hort. in Charge
E. G. Kelsheimer, Ph.D., Entomologist
David G. Kelbert, Asso. Horticulturist
E. L. Spencer, Ph. D., Soils Chemist
Robert O. Magie, Ph.D., Gladioli Hort.
J. M. Walter, Ph.D., Plant Pathologist
Donald S. Burgis, M.S.A., Asst. Hort.

Warren 0. Johnson, B.S., Meterologist

SHead of Department
2In cooperation with U. S.
SCooperative, other divisions, U. of F.
4On leave.

Florida Citrus Molasses

Clarification of Citrus Press Liquor


Introduction ...-...........--- .... .. .....------- ---...... -.... --. -......-------.. --------...- -- .. .. 5
Experimental Procedures and Results -... --....---.....--- ..- ---- 6
Clarification of Press Liquor ...........-- -....-- ... ...---- --. 6
Citrus Molasses from Clarified Press Liquor ..__ -_...... _- ....10
Discussion of Results ......--..._.....- .. -.... ..- -- -......... ----- -- 15
Clarification of Press Liquor -_....__ ....._. _____ _..............-- -------------- 15
Citrus Molasses from Clarified Press Liquor .. -..- ----.........--..... -.--- -- 18
Summary _-... --.. ...-...--... ..---......... ...-...-- -..-- ..----.--.....----............ 22
Acknowledgments ...---.. --........ ... ................. -.........- ._. -..... 23
Literature Cited .....-- .-.. .- -- ............ ..-.. .. ...-.........- ... .. ..... ..... ...-. ...------ 24

Since the 1941-42 canning season, when citrus molasses was
first commercially produced, there has been an expansive growth
in its production. As citrus molasses became more widely avail-
able, it proved to be an excellent carbohydrate concentrate and
simultaneously helped to solve a difficult waste disposal problem
of great moment to the mutual advantage of the citrus and cattle
industries. Besides a feed in itself, it has been successfully
used to ensil non-saccharin grasses, to pelletize dried citrus pulp,
and to increase the carbohydrate content of dried citrus pulp and
mixed feeds.
Citrus molasses is made by concentrating citrus press liquor
which is usually obtained by liming chopped citrus peel and
squeezing in continuous presses that expel the liquor as a very
turbid, straw-colored liquid. The press liquor contains 8 to 15
percent total dissolved solids, of which more than half are sugars.
Industrial practice is to pass this liquor through a coarse shaker
screen to heat exchangers. It is heated and flashed to both par-
tially deoil and precipitate calcium salts (9) prior to entering the
multiple-effect evaporators where it is concentrated to citrus
Citrus molasses at times has been subject to criticism, and for
this reason an investigation was undertaken to attempt improve-
ment in its qualities. A potential solution appeared to be the
'Italic figures in parentheses refer to Literature Cited in the back of this

Florida Agricultural Experiment Stations

clarification of citrus press liquor which would lead to the follow-
ing advantages: (1) a physically more attractive product, (2) a
lower viscosity, (3) a higher sugar content, (4) permit greater
concentration, thereby decreasing both water content and storage
space, (5) produce a molasses of lower ash content, (6) permit
filtration at a later stage, and (7) possibly improve its storage
In a second phase of this investigation samples of clarified
press liquor were concentrated to citrus molasses so as to under-
stand better its ultimate effect on the product. The clarified
citrus press liquors were prepared from different varieties of
citrus, and comparisons were made to show the effect of both
variety and clarification upon the final molasses.

Experimental Procedures and Results
Clarification of Press Liquor
Methods.-The clarification of any liquor or the separation of
suspended solids from liquids offers a number of alternatives,
each of which, alone or in combination, presents advantages,
limitations and degrees of success. Methods available can gen-
erally be divided into two classes: those in which the liquid is
still and the solids move through it owing to the force of gravity;
second, those in which the liquid passes through a porous mem-
brane of such character that the solid is retained. In the clari-
fication of citrus press liquor, which is an 8 to 140 Brix liquor
with approximately 1 percent suspended solids, methods classi-
fied under both classes were tried under the following circum-
Filtration.-Using filter papers of varying porosity, it was
found that filtration of citrus press liquor with and without suc-
tion was nearly always excessively slow. With the help of large
amounts of filter-aid, such as filter-cel, higher speeds of filtration
were possible, though the tendency was still for the more fine,
gelatinous suspended matter to close the pores that allow filtra-
tion. Higher temperatures both aided the agglomeration of the
suspended solids and increased the initial rate of filtration.
Screening.-The general practice of industry is to convey the
citrus press liquor through stainless steel shaker screens of ap-
proximately 40 mesh to eliminate the larger particles not with-
held by the continuous press. When citrus press liquor was

Florida Citrus Molasses

passed through a series of standard sieve screens extending down
to 200 mesh, it was found that the filtrate was still turbid and
cloudy, although considerable suspended matter was retained
that was well distributed in particle-size. There further appeared
a tendency for the more minute insoluble matter to close the
openings of the finer screens. At higher temperatures where
particle size is increased by agglomeration, the screen motion
necessary for filtration was sufficient to break the flocs.
Centrifugalization.-when various samples of citrus press
liquor were centrifuged at either high or low temperatures at ap-
proximately 2,000 r.p.m., the tendency was only to accentuate the
velocity of the suspended particles in the direction that they
would move over a more extended period of time. Since the press
liquor has varying proportions of suspended matter that both
sink and rise, it was difficult to get high clarity or good clear-cut
Flotation.-By the addition of a low density oil to citrus press
liquor an effective flotation of suspended solids was accomplished,
leaving a rather clear press liquor below. In this procedure vary-
ing quantities of d-limonene, benzene, and toluene were added to
the liquor and the mixture was thoroughly shaken and heated to
a higher temperature, then allowed to settle out in a separatory
funnel. When 2 percent of d-limonene, an oil that would be avail-
able at most molasses plants, was mixed with press liquor, 80
percent of the liquor could be drawn off clear after being held
half an hour at 70C. (158F.). A very small quantity of heavy
suspended matter quickly dropped to the bottom in this process.
When smaller quantities of solvent, or oil, were used, a decrease
in rate of flotation and final clarity resulted, whereas, large quan-
tities became more uneconomical.
Sedimentation.-On those occasions when press liquor was
made in the laboratory, the suspended insolubles were found to
settle quickly to the bottom, especially so when it was made from
grapefruit peel. Commercial press liquor, on the other hand,
maintained its insoluble solids in suspension for considerable
periods, except when it had passed through a flash chamber, after
which quicker and more complete settling was noticed. This
prompted investigation into the factors influencing rate of set-
Effect of Peel Oil.-Under the microscope press liquor ap-
peared as a liquid with a flocculent white precipitate, throughout

Florida Agricultural Experiment Stations

which were distributed minute oil droplets of varying sizes, so
small and scattered as to be physically withheld in the suspended
When press liquor was heated to 95C. (203F.) and flashed
into a vacuum, the settling rate of the suspended matter was
noted as increasing. Upon a second and third flashing of the
same press liquor with the consequent concentration, further in-
creases in the rate of settling could be seen. Data collected are
shown in Table 1, where it is to be noted that the total recoverable
oil has decreased in each case.

S Total Recoverable -Time For 50%
Sample* I Distilled off I Oil Content Clarification
______ ___% % (Minutes)
0 I 00 0.41 > 60
1 6.2 0.28 16
2 9.2 0.20 13
3 21.4 0.13 11
* Designates number of consecutive flashings.

When small amounts of d-limonene were added back to the
press liquor that was triple flashed it was found to restore the
original condition wherein the insolubles remained in suspension
for long periods of time.
When a large sample of press liquor was distilled in a side-arm
flask, the rate of clarification was measured for the individual
portions poured off following various distillation cuts. Table 2
presents data on the changes in peel oil content and rates of set-
tling. The first pour-off, sample A, was made just as the press
liquor reached boiling under atmospheric conditions. In Fig. 1
is shown the effect of partial distillation of press liquor upon the
clarification rate of its suspended solids.

Total Recoverable Time for 55%
Sample Distilled off Oil Content Clarification
% I % I (Minutes)
A 0.0 0.36 122
B 1.2 0.31 78
C 6.5 0.25 60
D 10.5 0.22 56
E 24.7 0.11 41

Florida Citrus Molasses



% "
% "


Fig. 1.- Influence of partial distillation of press liquor upon clarification

Florida Agricultural Experiment Stations

Effect of Temperature and pH.-When press liquor is first
heated, a gradual increase in insolubles is noticeable as the tem-
perature rises, which is more striking if the press liquor is pre-
viously filter ed. The suspended insolubles appear to agglomerate
as the temperature approaches the boiling point of the press
liquor, then increased convectional turbulence redisperses the
flocs. A scale begins depositing on the inner heat transfer sur-
face of the vessel and increases with prolonged boiling. The pH
of the press liquor all the while is undergoing a slow decrease.
Sixteen samples of press liquor on which pH was determined be-
fore and after heating to a boil dropped 0.2 of a unit. Upon pro-
longed heating, such .s the concentration of press liquor to citrus
molasses, which took ttiree to four hours in the laboratory, the
average pH drop for 14 samples was one unit.
The pH of the press liquor has a noticeable effect on the quan-
tity of suspended solids as well as the settling rate of those insol-
ubles. When the clarified, boiled press liquor is further limed,
considerable new quantities of flocculent suspended matter pre-
cipitated and quickly settled at above 60C. (140F.). Figure
2 compares the settling rates at approximately 8C. (46F.) for
four samples of press liquor, each with a different pH and pre-
pared from the same Duncan grapefruit peel.
Rate of Peel Oil Removal.-Press liquor is usually found to
have anywhere from 0.15 to 0.50 percent recoverable peel oil,
which is normally recovered by decantation from the distillate of
the flash chamber and multiple-effect evaporators as an additional
by-product. Press liquor from oranges was found to have a
higher peel oil content than press liquor from grapefruit peel,
but in both cases the peel oil steam distilled readily. Figure 3
plots the rate of peel oil removal from a press liquor having an
initial peel oil content of 0.36 percent. When the pH o the press
liquor is increased, the rate of peel oil distillation changes.
Figure 3 also shows the rate of peel oil removal from twA'o samples
of press liquor that differ only by the addition of a smal quantity
of lime to one sample in order to raise its pH.

Citrus Molasses from Clarified Press Liquor
Sixteen samples of citrus molasses prepared from'clarified
citrus press liquor were obtained in the following manner. Freshly
extracted pulp from the Citrus Experiment Station's canning

Florida Citrus Molasses

10 20 30 40 50
Time in Minutes

60 70

Fig. 2.-Influence of pH upon settling rate of suspended insolubles in
press liquor from Duncan grapefruit peel.


Florida Agricultural Experiment Stations


" 50

0 0



8RIX 20'C : 10.2*
O PH = 5.4
PH = 8.2

0 10 20 30 40


Fig. 3.-Influence of pH upon rate of peel oil removal from press juice
by distillation.

Florida Citrus Molasses

plant waste bin was chopped in a Fitzpatrick comminuting ma-
chine to pass a 1%1 or %1-inch screen. A weighed quantity of the
peel was then hand-mixed with about 1 percent of a 50 percent
lime slurry. After approximately half an hour, the press liquor
was expelled from the limed residue by either squeezing by hand
or hydraulic pressing a small quantity wrapped in cheese-cloth.
The expelled press liquor was then usually heated to its boiling
point, held for a few minutes, settled, decanted and further
clarified by filtering with the aid of filter-eel to assure the utmost
It is of interest to note that the press liquor from the peel
always has more soluble solids than the citrus juice of the same
fruit. Table 3 shows the results of a number of measurements
illustrating this point.

S No. of Press Liquor Fruit Juice
Citrus Variety Samples Average Brix Average oBrix

Hamlin 9 12.3 11.2
Valencia 8 13.8 11.9
Pineapple 3 14.3 13.0
Marsh 5 11.0 9.2
Duncan 4 13.3 10.7

The very clear press liquor was put in a four-liter suction
flask and concentrated batchwise under vacuum to 70-80 Brix.
Three or four hours of heating was usually required to con-
centrate the press liquor. During concentration scale invariably
formed on the inner heating surface, and when later breaking
loose it tended to increase foaming. The quantity of scale pre-
cipitated during concentration varied from sample to sample,
but it was found that the 50* Brix liquor could be easily filtered
to eliminate this same scale if the press liquor previously had
been clarified. It was further noted that increased precipitation
of scale could be obtained prior to this filtration by breaking the
vacuum and heating the 500 Brix liquor to 1000C. (212F.) for

Florida Agricultural Experiment Stations

a few minutes. The final concentrated liquor was put on the shelf
in 8 ounce sample bottles. After approximately three days new
insoluble matter was noted as precipitating in addition to a very
small amount of scale that was already on the bottom of the
bottles. After two weeks considerable quantities of insoluble
matter had precipitated in almost all samples and little increase
was thereafter noted. The insoluble matter slowly settled to the
bottom, though not too compactly, for in some cases it occupied
50 percent of the total volume. A good part of the insoluble mat-
ter when isolated was found to be insoluble in alcohol, whereas
the needle-like crystalline portion found in the grapefruit mo-
lasses samples was quite soluble in alcohol.
In one case where a press liquor sample was clarified and con-
centrated to 60 Brix citrus molasses, an attempt was made to
determine if pH was critical in the precipitation of this new in-
soluble matter. It was found for five identical samples with pH
adjusted with hydrochloric acid and sodium hydroxide to 3.9, 4.9,
6.0, 7.0, and 8.0 that approximately the same amount of suspend-
ed matter separated.
Table 4 presents the analyses of the 16 samples of citrus mo-
lasses prepared from laboratory prepared and clarified press
liquor. In the analyses only the clear top portions of the.citrus
molasses samples were used. Standard Association of Official
Agricultural Chemists methods (1) were followed, total sugars
as invert being determined by a 24-hour acid inversion and the
official Lane Eynon Volumetric Procedure.
Viscosities of the clarified citrus molasses samples presented in
Table 4 were determined at 30C. (86F.) with a Brookfield
synchro-lectric viscometer. The influence of concentration upon
the viscosity of citrus molasses was measured by diluting an
81.20 Brix partially clarified citrus molasses to various lower Brix
values and determining the viscosity at 30'C. (86'F.). Effect of
temperature upon viscosity was determined by diluting the same
sample to 75.00 Brix and measuring the viscosity at various tem-
peratures. This information is shown in Fig. 4.
Clarified molasses samples have shown excellent stability for
over six months without the slightest sign of foaming, or sub-
surface gas formation. However, molds profusely multiplied on
the surface and had to be controlled with toluene.

Florida Citrus Molasses


Type of citrus peel > 9 1 0o
3 0 u2 M ;0o0 a4
o_ ) o Cq F
___________ ____ -o '-- E _




































% Apparent Purity = % Total sugars X 100
Brix by refractometer

Discussion of Results

Clarification of Press Liquor

Investigation of methods of clarifying citrus press liquor
appeared to indicate that sedimentation offered a most potential
solution. Since the insolubles are minute, slimy and pectinous in
character, filtration by most methods was unnecessarily slow
with and without suction; even filter-aids did not sufficiently in-
crease filtration rates. Screens of mesh adequately fine for good

16 Florida Agricultural Experiment Stations

Degrees Brix
60 64 68 72 76 80 84

800- 0 Temperature vs Viscosity

600 0 Degrees Brix vs Viscosity
At 75.0 0 Brix
S--- At 30.0 Centigrade


o \ /
S100 -
80 -

o i

c 20-


0 I/


0 10 20 30 40 50 60 70
Temperature *C.

Fig. 4.-Influence of concentration and temperature upon the viscosity
of a partially clarified citrus molasses.

Florida Citrus Molasses

clarity were subject to the same tendency of the fine flocculent
suspended matter to close the pores that allow separation. Flota-
tion appeared to offer possibilities, but would not appear to
justify precedence over a sedimentation process. In both cen-
trifugalization and sedimentation, the greatest interference was
due to the physical adherence of peel oil to the suspended
solids lending a buoying action by virtue of its lower specific
gravity. Decreasing the peel oil content by distillation effectively
increased the settling rate of insolubles, as seen in Tables 1 and
2 and Fig. 1. Since the peel oil steam distills readily, partial dis-
tillation with the consequent reduction of recoverable peel oil in
the press liquor sufficiently reduces the buoying action on the in-
solubles, thereby permitting a more rapid and complete settling.
The rate of peel oil removal by distillation, however, is subject to
a number of factors of which temperature and degree of equi-
librium established are most important. Peel oil from oranges or
grapefruit is roughly 95 percent d-limonene which steam distills
with ease in ratio of about 1 part d-limonene to 2 parts water
under atmospheric conditions, when present in sufficient quantity
to insure equilibrium conditions for the two-phase system. When
oil is present in small quantities, such as in press liquor, continu-
ously decreasing ratio of oil to water is noted in the distillate (see
Fig. 3), which is further accentuated by distilling the press liquor
on the alkaline side. This decreasing rate is probably due to the
difficulty of obtaining proper equilibrium conditions when only a
small quantity of oil is present, as well as being inhibited by
physical attraction of the oil to the suspended insolubles, which
are generally increased by raising the pH of the press liquor.
Figure 3 would further indicate that processors entertaining
thoughts of clarification by sedimentation should consider the ad-
vantages of greater distillate cuts prior to settling than are now
obtained in their flash chambers. A more completely deoiled
press liquor with the resulting increased settling rates would
permit shorter holding periods and greater capacity for sedimen-
tation equipment of the same size.
Indications to date have shown that among other considera-
tions important to high settling rates, the degree of liming plays
an important part. Spencer and Meade (10), in discussing the
clarification of cane juice which is a strikingly similar problem,
relate the various methods and aspects of optimum liming as

Florida Agricultural Experiment Stations

well as listing 622 compounds that have been used in the past to
clarify, decolorize and purify sugar-containing solutions. Figure
2 shows settling rates to be related to pH, with more rapid set-
tling being obtained at the higher pH. This relationship invari-
ably followed in many other experiments, although neither maxi-
mum nor optimum conditions were determined. It is felt, how-
ever, that consideration must be given to the destructiveness and
other inherent disadvantages of excessive lime on sugars.

In the settling of a solid through a fluid, such as in the sedi-
mentation of press liquor, it is generally acknowledged as taking
place in three stages-the first being known as free settling, the
second as a transition period and the third stage as impeded set-
tling. In a discussion of the theory of sedimentation, Badger
and McCabe (2) use the following formula:

d x kD2 (P' P)
dt w
x = Height in unsettled press liquor
D = average suspended particle size
P' = density of particle
P = density of unclarified portion
w = viscosity of unclarified portion
k = constant
t = time

It is apparent, therefore, that raising the temperature de-
creases viscosity and gives higher settling rates. At higher tem-
peratures, agglomeration of suspended matter occurs and is in-
strumental in effecting faster sedimentation, since it increases
the average suspended particle size. The addition of lime has
been noted as both precipitating further insoluble matter, that
is thought to have a higher density, and aiding agglomeration,
which would further increase the settling rate.

Citrus Molasses From Clarified Press Liquor

Clarified and concentrated press liquor is a dark, clear, semi-
viscous liquor that more nearly resembles the familiar edible
molasses than the brown, turbid commercial product. Its appear-

Florida Citrus Molasses

ance is marred only by a later precipitation of insolubles during
Since the insolubles originally present in citrus press liquor
are non-sugars high in ash content, their physical removal is in-
strumental in raising the total sugar content of the clarified pro-
duct. The magnitude of this increase is shown in Table 5, where
average analyses for clarified and non-clarified samples are pre-
sented on a comparable calculated 75 Brix basis. Irrespective
of variety, clarified and concentrated samples were noted as hav-
ing a higher sugar content than the non-clarified commercial
product, with orange molasses samples being higher than grape-
fruit samples.
SWhen the average ash content of the clarified samples is com-
pared against that of the commercial unclarified product on a 75
Brix basis as in Table 5, a considerable decrease in ash content is
noted that can be attributed to clarification of press liquor.
Samples of clarified orange molasses have a lower ash than clari-
fied Marsh grapefruit molasses. The Duncan samples, however,
were found to have exceptionally low ash content.
Variations in viscosity of citrus molasses are so wide that
Brix is neither a reliable measure of, nor indicative of, viscosity.
However, in terms of any one sample, viscosity increases with
Brix and decreases as the temperature rises. Figure 4 shows the
effect of both concentration and temperature upon the viscosity
of a partially clarified citrus molasses sample. A comparison
showing the relative effect of clarification of press liquor is most
difficult because of variations in the Brix of samples, and the
large viscosity dispersion for samples at any one Brix. To avoid
this difficulty, as well as to eliminate the choice of a representa-
tive sample from each group, a scatter diagram, Fig. 5, was
plotted to show the viscosities at 30C. (86F.) of 12 samples of
non-clarified molasses (8) versus those at 300C. (860F.) for 15
samples of clarified molasses. The equation for the regression
line of each group of samples was determined and plotted to show
better the comparison between clarified and non-clarified samples.
It indicated for any Brix, between the limits expressed on the
scatter diagram, that the viscosity of the non-clarified commercial
samples was more than seven times that of the clarified samples.
The clarified product, therefore, could be concentrated much
further without exceeding the viscosity of the presently manu-
factured non-clarified product.


Description of Molasses Samples

Season Variety Press Liquor

1947-48' Commercial Not clarified

1947-482 Commercial Not clarified

1948-49 Marsh Clarified

1948-49 Duncan Clarified

1948-49 Pineapple Clarified

1948-49 Hamlin Clarified

1948-49 Valencia Clarified









XCd rd C : d 2d
o C,> 0> >o
S'l I F4 03 0
"Qi5S~l I 1 i 0U






















Calculated to 750
Brix Basis

Total Suga Ash Content
as Invert

Hendrickson (5).
SIranzo and Veldhuis (8).
1 Average for 10 samples whose average Brix was 71.0.

Florida Citrus Molasses 21

90 Regression Line, Non-clarified Molasses
70 Regression Line, Clarified Molasses
60 /
50- O /
40 /-

30- /
0 0/
o 00 /
0O /
I" 20 -/


s /o/

4 -

Clarified /M
c 9 / '
8 6- 0


3 0


0 Non-clarified Molasses

0 Clarified Molasses

68 70 72 74 76 78 80
Degrees Brix
Fig. 5.-A scatter diagram comparing the viscosities at 300 C. of 15
samples of citrus molasses from clarified press liquor with the viscosities at
300 C. of 12 samples of non-clarified citrus molasses.

Florida Agricultural Experiment Stations

Sixteen samples of citrus molasses from clarified press liquor
showed excellent stability for a period of six months, and al-
though no gas evolution measurements were made, visual in-
spection has shown no signs of sub-surface gas formation, or
foaming at the surface. A previous investigation of the stability
of commercial citrus molasses indicated that some samples
evolved considerable gas and tended to foam readily when dis-
turbed. The chief cause of spontaneous decomposition of black-
strap, which is very similar to citrus molasses, is attributed by
Browne (4) to the reaction of unstable organic substances with
further quantities of reducing sugars in the molasses. Also the
Maillard reaction, a reaction between the amino acids and reduc-
ing sugars, is thought to play a minor role in the early stages of
decomposition. Microorganisms are believed to have only a small
overall effect (6, 7). The apparent excellent stability of the
laboratory clarified samples is probably best accounted for by the
removal of some colloidal, unstable organic substances contribut-
ing to instability. This clarified citrus molasses also has the
further advantage of having a less stable foam system, for
among the conditions contributing to stable foams, according to
Berkman and Egloff (3), are high viscosity and finely divided
solids, both of which have been reduced by clarification. Thus
foaming is not apt to be as serious a problem in the manufacture,
storage and shipment of citrus molasses if clarified press liquor
is used in its manufacture.
Representatives of the molasses industry have long recog-
nized that citrus molasses, upon storage, tends to increase in vis-
cosity, sometimes appearing to gel. That the viscosity increases
during storage is readily noticeable by visual examination alone.
It seems evident from the considerable precipitation of insolubles
during storage in the citrus molasses samples made from clari-
fied press liquor that this same condition exists in the non-clari-
fied product and is responsible for its increased viscosity, but has
not been previously recognized because of the quantities of in-
soluble matter already present.
The clarification of citrus press liquor was investigated and of
the five methods tried, filtration, screening, flotation, centrifugal-
ization and sedimentation, the last appeared to be the most ad-

Florida Citrus Molasses

The slimy, pectinous, suspended solids were microscopically
seen as physically entrapping or attracting minute peel oil drop-
lets. The oil, by virtue of its low density, gave a buoying force
to the suspended matter which prevented rapid or complete sed-
imentation. The settling rate of the insolubles was dependent
on the degree of peel oil removal which was effected by partial
distillation of the press liquor. Manufacturers now practicing
partial clarification would appear to benefit by more complete re-
moval of peel oil. This could be accomplished by further distilla-
tion prior to settling.

Clarified press liquor from different varieties of citrus peel
produced upon concentration a much improved citrus molasses
that was physically more attractive, of high sugar content and
lower ash than the unclarified commercial product analyzed dur-
ing the 1947-48 season. The clarified product was further noted
as being more stable and as having a much lower viscosity.
Furthermore, it seems evident that precipitation of insolubles
during storage occurs in both clarified and non-clarified molasses,
is responsible for increased viscosity of the non-clarified product,
but has not been previously recognized because of the quantities
of insoluble matter already present.

Citrus molasses from clarified press liquor appears to offer
sufficient physical and chemical advantages to prompt its indus-
try-wide adoption. When carefully manufactured and stan-
dardized, it should command recognition as an outstanding carbo-
hydrate concentrate.


Grateful acknowledgments are made to the commercial processors and
manufacturers in Florida whose cooperation contributed to the success of
this work. Citrus molasses samples used in part of this study were obtained
from Florida Fruit Canners, Inc., Frostproof; Peace River Canning Com-
pany, Wauchula; Florida Molasses Corporation, Lake Alfred; Florida Citrus
Canners Cooperative, Lake Wales; Kuder Citrus Feed Company, Bartow;
Kuder Citrus Pulp Company, Lake Alfred; Pasco Packing Company, Dade
City; Plymouth Citrus Growers' Association, Plymouth; Suni-Citrus Prod-
ucts Company, Haines City; Southern Fruit Distributors, Orlando; Winter
Garden Citrus Products Cooperative, Winter Garden; Adams Packing As-
sociation, Inc., Auburndale; and J. William Horsey Corporation, Plant City.
For all their courtesies and contributions the author expresses his apprecia-
tion and thanks.

24 Florida Agricultural Experiment Stations

Literature Cited
1. Association of Official Agricultural Chemists. Official methods of analy-
sis. 6th Ed., 932 pp. 1945. Washington, D. C.
2. Badger, W. L., and W. L. McCabe. Elements of chemical engineering,
2nd Ed., 660 pp. 1936. McGraw-Hill Book Co., Inc.
3. Berkman, S., and G. Egloff. Emulsions and foams. 591 pp. 1941. Rein-
hold Publishing Co.
4. Browne, C. A. The spontaneous decomposition of sugar-cane molasses.
Ind. Eng. Chem. 21: 600-06. 1929.
5. Hendrickson, R. Stability of citrus molasses. Fla. Agr. Exp. Sta. Ann.
Report. 1948. 184-5.
6. Henry, R. E., and R. F. Brooks. Chemical decomposition of cane sirup
and molasses during storage. Abs. of the Sept., 1947, A.C.S. Meeting.
7. Hucker, G. J., and R. F. Brooks. Gas production in storage molasses.
Food Research 7: 481-92. 1942.
8. Iranzo, J. R., and M. K. Veldhuis. The composition of Florida citrus
molasses. Proc. Fla. State Hort. Soc. 61: 205-211. 1948.
9. Pulley, G. N. Treatment of citrus waste press water. U. S. Patent No.
2,471,893. May 31, 1949.
10. Spencer, G.: L., and G. P. Meade. Cane sugar handbook. 8th Ed., 834
pp. 1945. John Wiley and Sons, Inc.


The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source

site maintained by the Florida
Cooperative Extension Service.

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