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TWENTY-FIRST ANNUAL CITRUS
FLORIDA CITRUS EXPERIMENT STATION
Lake Alfred, Florida
STATE OF FLORIDA DEPARTMENT OF CITRUS
AGRICULTURAL EXPERIMENT STATIONS
INSTITUTE OF FOOD AND AGRICULTURAL SCIENCES
UNIVERSITY OF FLORIDA; GAINESVILLE
Citrus Experiment Station
Mimeo Report CES 71-7
The entire research group at Lake Alfred extends a cordial welcome to
sitors attending the Twenty-First Annual Citrus Processors Meeting. We
pe you find your visit pleasant and the research reports of value.
The citrus industry seems to be anticipating serious economic stresses
the years ahead, and similar economic stresses worry research admini-
rators. Funding of research by most organizations is leveling off or
clinging after many years of steady increase. Effective demands are being
de that research be made even more relevant to current problems. Evalu-
ion of research by program planning and budgeting is becoming more wide-
iread. Inflation reduces the value of static budgets. Additional
rsonnel for any project are very difficult to obtain.
Consequently, we intensify our efforts to identify important, attain-
le, and reasonable research problems, and concentrate our resources upon
ose. No longer can new money be readily obtained to work on problems of
condary economic importance.
Up to a point, we welcome these new attitudes and procedures, and the
onomies and stresses they produce. But we hope they do not become a set
strictures on real research, nor a mechanism for converting research
ganizations into direct service organizations. We count on your support
improve our research program.
Herman J. Reitz
Horticulturist and Head
Citrus Experiment Station
Last year we adopted a new format consisting of abstracts rather than
11-length printed papers. We also used a large number of short pre-
.ntations to give exposure to a wide range of problems. This format was
11 received and we are following it again this year. However, suggestions
r improvements in our presentations are always welcome.
The Department of Citrus staff again wishes to express its appreci-
ion to the University of Florida Citrus Experiment Station whose continued
operation made our work possible.
John A. Attaway
VDirector of Scientific Research
Florida Department of Citrus
University of Florida
Citrus Experiment Station
P. O. Box 1088
Lake Alfred, Florida 33850
Thursday, October 8, 1970
8:30 A.M. Registration
,9:30 A.M. WELCOME
Herman J. Reitz
Horticulturist and Head
Citrus Experiment Station.
Robert S. Kazaros
Chairman, Scientific Research Committee
Florida Citrus Commission
Chairman: David 0. Hamrick, Tropicana Products, Inc., Bradenton.
9:50 A.M. COLOR STANDARDIZATION OF PIGMENTED GRAPEFRUIT JUICES -
R. L. Huggart, Chemist III, and S. V. Ting, Research
Biochemist, Florida Department of Citrus, Lake Alfred.
Pigmented grapefruit (pink), consisting largely of 'Ruby Red' and
similar varieties, have been planted extensively because of their ready
acceptance on the fresh fruit market. Of the December 1969 total of
98,665 acres of bearing grapefruit, 26,396 acres or 26.8 percent are in
the variety listed as 'Pink Seedless'.
Processors used 65 percent of the 40 million box grapefruit crop
utilized during the 1968-69 season ending July 31. Pink grapefruit
accounted for 19 percent of the fruit going to the canners. The Florida
Department of Citrus estimates grapefruit bearing acreage could increase
by as much as 37 percent by 1972.
Due to the excellent consumer demand for processed grapefruit juices,
canners are utilizing all fruit available. Especially prepared select
packs of pink grapefruit juice are processed by plants using a large
volume of pink grapefruit during optimum color maturity. Small volumes
of pink grapefruit create a problem in the cannery because the addition
of pink juice to normally white grapefruit juice results in a canned
product that has a muddy, nondescript color.
Methods of standardizing pink grapefruit juice colors are discussed.
Data are presented to show juice colors of three varieties of pink grape-
fruit during a season. Packs were prepared in tin and enamel lined cans
with standardized juice colors using Certified Pure Food Colors and
synthetic carotenoids. Color and flavor changes were determined in the
juices which were stored at 800F.
10:05 A.M. PHYSICAL AND CHEMICAL CHARACTERISTICS OF COMMERCIAL FCOJ
PACKED DURING THE 1969-70 SEASON R. W. Barron, Chemist II,
and R. W. Wolford, Research Chemist, Florida Department of
Citrus, Lake Alfred.
A total of 217 samples of commercial FCOJ were examined for flavor
and color during the 1969-70 citrus season. In addition, physical and
chemical analyses relating to juice quality were conducted. Hunterlab
Citrus Colorimeter CR and CY average values this season were about the
same as those for the two previous seasons.
Using numerical averages of flavor scores, 34 samples from the
1969-70 season were divided into four arbitrary flavor groupings based
on the CES 10-point score sheet. The flavor groupings were 6.0, 6.5,
7.0, and 7.5. Correlation coefficients were developed using several
characteristics of the juices as independent variables and flavor as
the dependent variable. Similar relationships were developed for the
1968-69 and 1967-68 seasons.
10:20 A.M. A QUANTITATIVE TOTAL ALDEHYDES TEST USEFUL IN EVALUATING
AND BLENDING CITRUS ESSENCES AND CONCENTRATED CITRUS
PRODUCTS Donald R. Petrus, Chemist III, Marshall H.
Dougherty, Research Engineer II, and Richard W. Wolford,
Research Chemist, Florida Department of Citrus, Lake Alfred.
A quantitative colorimetric test using N-hydroxybenzenesulfonamide
in an isopropanol system to determine the total aldehyde content of
citrus juices, essences, and processed citrus products is discussed.
Data and results are given illustrating the applicability of the test
for blending citrus essences and concentrated citrus products.
10:35 A.M. A COLORIMETRIC METHOD FOR THE QUANTITATIVE DETERMINATION
OF TOTAL ALDEHYDES IN COLDPRESSED ORANGE AND GRAPEFRUIT
OILS Marshall H. Dougherty, Research Engineer II, and
Donald R. Petrus, Chemist III, Florida Department of
Citrus, Lake Alfred.
The accepted method for determining the aldehyde content of cold-
pressed citrus oils is the hydroxylamine hydrochloride method, of which
there are many variations. The United States Pharmacopia, The Associ-
ation of Official Agricultural Chemists and the Essential Oil Association
of the United States all describe hydroxylamine hydrochloride methods and
each are slightly different. They embody variations in reaction time,
frequency and degree of shaking, end points, and indicators. It is quite
likely that two analysts, using the same hydroxylamine method on the same
sample, could get different results because of different interpretations
of the method and their own individual techniques.
A colorimetric method for the quantitative determination of the
aldehyde content of coldpressed orange and grapefruit oils is presented.
The method employs N-hydroxybenzenesulfonamide and may be conducted in
conjunction with the analyses of citrus essences and juices for total
aldehyde content since the same standards and reagents are utilized.
Data for reproducibility, standard curves and sample analyses are given
and discussed. Equations are given for conversion of results to percent
10:50 A.M. BREAK
11:05 A.M. AUTOMATIC BRIX DETERMINATION James G. Blair, Research
Engineer III, Florida Department of Citrus, Lake Alfred.
While the present spindle hydrometer method used to measure Brix
of citrus in the State Test Rooms is in principle quite accurate, it
does not lend itself to automation and is influenced by human errors.
For these and other reasons, it is highly desirable to automate the
Brix determination as made in the State Test Room. Two automatic Brix
readers are under test at the present time, and it appears as though we
are getting close to something that will be acceptable.
One machine was operated at one of the processing plant locations
for about a month the later part of the past season. After the initial
installation check-out, the machine operated maintenance free for the
entire test period. A comparison of results was made with the official
hydrometer measurement. The figures were not as good as we hoped for
but they were consistent and may be improved by minor modifications.
The second Brix reader was received very late in the season and
our field experience with it was not good although it might have been
possible to correct some of the problems if there had been more time.
Both of the machines have been under test at the Citrus Experi-
ment Station this summer and we have plans for comprehensive tests
this coming season.
11:20 A.M. THE STATUS OF ABSCISSION CHEMICALS ON FRUIT FOR PROCESSING
W. C. Wilson, Plant Physiologist II, and J. F. Fisher,
Research Chemist, Florida Department of Citrus, Lake Alfred
Cycloheximide has proven to be an excellent abscission-producing
chemical for early and midseason oranges, provided application is made
before the spring growth flush begins. Its status on 'Valencia'
oranges is uncertain pending the results of extensive yield tests.
(The chemical is known to cause injury to young, immature fruit for an
undetermined period following bloom). The Upjohn Company has petitioned
FDA requesting an expanded experimental label to allow limited quanti-
ties to be sold for use on early and midseason oranges this coming
season under the trade name Acti-Aid.
Weak acid chemicals such as ascorbic, erythorbic, and citric acids
can cause fruit splitting on early oranges some years, but may have some
possibilities late in the midseason orange period. They are more
erratic in performance than cycloheximide, and cannot be used on
'Valencias' because of injury to young, green fruit.
No adverse effects on juice quality have been noted in formal test
(Mr. Clifford Scott, USDA), and informal observations by individual pro
cessors, conducted on fruit treated with abscission chemicals. Prelimi
nary work indicates little or no cycloheximide enters the juice of pro-
cessed fruit, most of the residue remaining on the peel.
The need for closer cooperation between processing and harvesting
units of concentrate operations in utilization of "loosened" fruit, the
physical condition of such harvested fruit, and the special problems of
the 'Valencia' orange are also discussed.
11:35 A.M. FACTORS AFFECTING AIR POLLUTION ASSOCIATED WITH CITRUS FEED
MILL OPERATIONS H. A. Ingley, PhD Candidate, University
of Florida, Gainesville, J. W. Kesterson, Chemist, Universi
of Florida Citrus Experiment Station, Lake Alfred, C. C.
Oliver, Associate Professor of Mechanical Engineering, and
R. S. Sholtes, Chairman, Department of Environmental Engi-
neering, University of Florida, Gainesville.
This presentation discusses several of the variables which are
believed to have an influence on the emissions from citrus feed mill
stacks. Many of these variables are currently under study at the
Citrus Experiment Station and these are presented in more detail. The
economic value of the recoverable feed mill emissions is also con-
11:55 A.M. SCIENTIFIC RESEARCH AND TECHNOLOGY CAN MEAN EXPORTS, THUS
PROFIT FOR FLORIDA CITRUS Walter C. Loesche, Inter-
national Marketing Director, Florida Department of Citrus,
There is currently a great need for new products and improved pro-
cessing methods, and a necessity exists for new markets. Particularly
in the export area, these two major needs meet. Why is this so? Over-
seas and in Canada, Florida has processed product competition
We all recognize that Florida has the best juice citrus in the
World as well as top technology, and everyone else in the trade in other
countries recognizes this, too. As a result, Florida is enjoying a boom
in export sales. These rapidly increasing export sales are exactly the
answer to a good part of the new market need caused by our rapidly in-
creasing size of crops. And the Florida Department of Citrus is doing
its job through the extremely successful Three Party Program to stimu-
late rapidly increasing overseas demand for Florida. The Department is
also taking many other actions to open these new and large markets to
Florida citrus. However, Florida can only hold a good part of these
important sales if its scientific and technological progress maintains
Florida's processed product superiority over the competition found in
other markets. Other citrus producing areas are working hard at trying
to match us and, even through what could be called unfair copying, beat
us out of markets.
It is imperative that the Florida citrus industry maintain its
product superiority. If this is done, seeing the progress being made
in overseas markets, the Florida grower and processor can be assured
of profitable citrus business in the future.
12:15 P.M. L U N C H
Chairman: Ralph Brincklow, H. P. Hood & Sons, Inc., Dunedin.
1:35 P.M. PROGRESS AND GOALS IN PROCESSING RESEARCH J. A. Attaway,
Director of Scientific Research, Florida Department of
Citrus, Lake Alfred.
Processing research by the Florida Department of Citrus and the
University of Florida Citrus Experiment Station is being carried out
in 4 principal areas. These are the Production and Use of Citrus
Essences, Quality of Processed Products, Color Improvement, and New
Product Research and Development.
In new product research we are principally concerned with high
density concentrates, juice blends, protein fortified juices, drink
bases, and citrus gels and sauces. The color improvement group is
studying new means for recovery of natural pigments of orange and new
techniques to obtain more satisfactory color in pink grapefruit juice.
The quality group is carrying out further investigations of the role
of viscosity, pulp, pectins, etc. in juice quality, and is making an
intensive effort to develop chemical and physical criteria for the
definition of orange juice. In essence research our main concern is
the proper blending of essence with various processed products.
1:55 P.M. NEW CITRUS PRODUCTS RESEARCH Paul J. Fellers, Food
Technologist, Florida Department of Citrus, Lake Alfred.
General procedures used by the New Citrus Products group at the
Citrus Experiment Station are discussed including such items as new
product concepts, economics of using pure citrus products, types of
products being studied, advantages and disadvantages of working with
citrus, patents, problems in procuring ingredients, sensory evaluation
procedures, storage tests, test marketing, product showings to industry
and so forth.
2:10 P.M. NUTRITIVE PROTEIN SUPPLEMENTS FOR NEW CITRUS PRODUCTS -
M. D. Maraulia, Chemist II, and C. D. Atkins, Research
Chemist, Florida Department of Citrus, Lake Alfred.
Problems encountered in the fortification of citrus juices and con-
centrates with protein materials are discussed. Desirable and undesirab:
properties of conventional and nonconventional protein supplement materi
als which determine their usability in preparing protein fortified citrus
products are considered. Nutritional values of the standard protein
food supplements and single-strength orange juice are outlined taking
into consideration the essential amino acid content. The characteris-
tics of protein fortified citrus products that determine consumer
acceptance and marketability are compared with those of orange juice.
2:25 P.M. FACTORS CONTRIBUTING TO THE VISCOSITY OF HIGH DENSITY FCOJ -
A. H. Rouse, Chemist, University of Florida Citrus Experi-
ment Station and E. L. Moore, Research Chemist, Florida
Department of Citrus, Lake Alfred.
The following factors or combination of them cause viscosity in
high density FCOJ. Low methoxyl pectin that forms gels in the presence
of divalent ions, such as calcium; water-soluble pectin; protopectin;
polymerization of the pectin molecule; water-insoluble solids (WIS); and
the creation of a sugar-pectin-acid gel system. Concentration of these
factors under certain conditions can produce extremely high viscosities
in citrus concentrates that either approach or are greater than 65 Brix.
Experimental packs of 'Hamlin', 'Pineapple', and 'Valencia' orange
juices containing low (4%), medium (8%), and high (12%) pulp levels were
concentrated in the Atkins evaporator. Samples were removed at 3-, 4-,
5-, 6-, and 7-fold, sealed into 12-oz. cans and stored at -8F. until
analyzed. In these samples the pulp was in contact with the juice
throughout the evaporation.
Packs of 5.33- and 6-fold were prepared from the 7-fold juices
above containing either the 4% or 8% pulp level and cut back with a
combination of low pulp juice and pulpy juice so that the finished
products contained a medium and high pulp level. These high density
packs contained added pulp that was not in contact with the juice
during evaporation. All samples were stored at -80F.
Four commercial high density products were also examined. Two of
these had viscosities less than 11,500 cps and two had viscosities over
The Brookfield Viscometer, Model LVT, was used to measure apparent
viscosities of all products. Only those dial readings near the center
of the dial were used for calculation. Products were measured at 780 -
The Following Experimental Packs Had Viscosities Over 8,000 Centipoises
Hamlin, 7-fold, 9.0% pulp - - - 8,880
Hamlin, 7-fold, 11.9% pulp - - - 46,800
Pineapple, 7-fold, 8.1% pulp - - - 8,540
Pineapple, 6-fold, 12.0% pulp - - - 22,160
Pineapple, 7-fold, 12.0% pulp - - - 87,000
Examination showed the following characteristics present in these
high viscosity packs:
1. Definitely thixotropic in behavior.
2. High water-insoluble solids (over 600 mg/100 g cone.).
3. Either a high quantity of water-soluble pectin (over 210
mg/100 g conc.) or a high amount of protopectin, the
sodium hydroxide-soluble pectic fraction, (over 260
mg/100 g conc.).
4. High quantity of total pectin (over 550 mg/100 g conc.).
5. Creation of a sugar-pectin-acid gel system (when concen-
tration approaches 65Brix).
6. Polymerization of pectin from extracted pulp of high density
commercial products having high viscosities was greater, as
indicated by jelly grade, than pectin from extracted pulp
of high density products with lower viscosities.
7. In most products, a higher viscosity by Brookfield was found
after freezing and thawing than in the corresponding "pump-
Five of the 5.33-fold (56.60 Brix) experimental packs ranged in
viscosity from 760 to 2,515 cps. The sixth pack had a viscosity of
7,200 cps and the WIS was 1,111 mg/100 g concentrate.
2:50 P.M. B R EAK
3:05 P.M. CONCERNS ABOUT NUTRITION AND CHANGING FOOD HABITS -
R. A. Dennison, Chairman, Food Science Department,
University of Florida, Gainesville.
For any population group the food supply available and the food
habits have a major influence on the health and well-being of the people
In the United States in recent years there has been a steady decline in
the number of families receiving good diets. The dietary allowances for
calcium, vitamin A, ascorbic acid, iron and other nutrients are not
being met for many individuals. Some of the decline in good dietary
practices appears to be related to the movement of large numbers of
families from farms to urban centers, the increased eating away from
home, and the appeal for limiting food selection to convenience and
3:30 P.M. THE ENZYMATIC DEBITTERING OF GRAPEFRUIT PRODUCTS -
E. C. Hill, Research Bacteriologist, Florida Department of
Citrus, R. W. Olsen, Biochemist, and F. W. Wenzel, Chemist,
University of Florida Citrus Experiment Station, Lake
Alfred, and F. P. Griffiths, Research Food Technologist in
Charge, USDA, ARS, Food Crops Utilization Research Labora-
tory, Weslaco, Texas.
The bitterness in grapefruit is mostly due to the presence of the
flavanone glycoside, naringin. This compound which helps to give grape-
fruit its characteristic flavor can be present in such quantities that
the bitterness can make the product unpalatable. Naringin can be hydro-
lyzed to a non-bitter substance with an enzyme, naringinase, which has
been made in this country on a pilot plant scale and is being produced
by a Japanese firm on a commercial scale. Naringin is hydrolyzed to
slightly bitter prunin, tasteless naringenin and rhamnose. For chemi-
cal analyses, the Davis test must be preceded by hydrolysis of prunin
using another enzyme, emulsin, which changes prunin to naringenin and
glucose. The debittering activity of naringinase is affected by temp-
erature, time and concentration of enzyme. The optimum temperature is
1220F and activity ceases at 1800 and -8"F. The enzyme does not affect
vitamin C, color or cloud of grapefruit products. Although naringin
content in all grapefruit products can be reduced enzymically, only
chilled grapefruit sections and grapefruit pulp-washed solids lend them-
selves to an economically practical use of this process at this time.
Since chilled sections are not pasteurized, the enzyme can be dissolved
in the sugar syrup or juice in which the sections are packed. The long
shelf life for sections gives ample time for a low concentration of
enzyme to act. At the present commercial price for the Japanese enzyme,
the cost would be approximately $0.75 per 1000 1-lb. jars using a
concentration of 0.005%.
Pulp-washed solids which can be intensely bitter are usually
pasteurized before being concentrated. This material could be removed
from the pasteurizer after being cooled to 1220F (optimum temperature),
the enzyme added and held. The naringin content would be reduced to a
satisfactory level within 30-60 minutes at 0.1% enzyme concentration.
3:45 P.M. PROSPECTS FOR THE FERMENTATION INDUSTRY IN FLORIDA -
Sterling K. Long, Associate Industrial Bacteriologist,
University of Florida Citrus Experiment Station, Lake
The current status of fermentation industries in the citrus-
producing area of Florida will be presented and the effect of such
industries on local and state economies discussed. The outlook for
expansion of such industries, including effect on agriculture and
utilization of land, new products and by-products, and waste treatment,
will be considered.
These Abstracts are for limited distribution only. Information
herein is not to be used for publication without permission.
Acknowledgment for helpful assistance is made to Fred Schopke, Ben
Wood, Irene Pruner, Louise Cherry, Mary Smith, Roger Waters, Joe Collin
Fred Givens, Roy Albright, Van Harrell, and to all other personnel of
either the University of Florida Citrus Experiment Station or the
Florida Department of Citrus who helped in many and various ways.