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University of Florida
Agricultural Research & Education Center
P. O. Box 1088
Lake Alfred, Florida 33850
9:00 A.M. Registration
9:30 A.M. Welcome
John A. Attaway
Scientific Research Director
Florida Department of Citrus
Lakeland and Lake Alfred, Florida.
Chairman: Howard W. Trumm, Citrus Exporter, Ocala, Florida.
9:45 A.M. MINERAL NUTRIENTS OF CITRUS JUICES S. V. Ting, Research
Biochemist, Florida Department of Citrus, Lake Alfred.
The ash from citrus juices has been found to contain many chemical
elements. Potassium is by far the most abundant mineral, comprising
nearly 60-70% of the total ash, but the sodium content is very low.
Other elements found in respectable quantities include calcium,
magnesium, and phosphorus, while lesser amounts of iron, copper, zinc,
manganese, boron, strontium, barium, aluminum and chromium are found.
In the recent Nutrition Labeling Act of the Food and Drug
Administration, the Recommended Daily Allowances (RDA) established by
the Food and Nutrition Board of the National Research Council for the
known nutrients, including the inorganic elements, were adopted. In
the list of eight nutrients required for labeling, there are two
inorganic elements, namely iron and calcium. The U.S. Recommended
Daily Allowances for these two elements are 18 and 1000 mg. respect-
ively. The amounts of these two elements in reconstituted FCOJ were
found to be less than 2% of the U.S. RDA in a 6 fl. oz. sample.
Phosphorus, magnesium, copper, zinc, and iodine are the other essential
mineral nutrients specified as optional by the Nutrition Labeling Act.
The U.S. RDA for these elements are: phosphorus, 1000 mg; magnesium,
400 mg; copper, 2 mg; zinc, 15 mg; and iodine, 0.15 mg. Reconstituted
FCOJ was found to contain about 3% RDA phosphorus, 47, U.S. RDA magnesium,
6% U.S. RDA copper, and less than 1% U.S. RDA zinc. Determinations for
iodine have not been completed.
10:00 A.M. ANALYSIS OF THIAMINE AND NIACIN IN ORANGE JUICE -
J. W. McAllister, Assistant Officer-in-Charge,
Processed Food Inspection, U.S.D.A., Winter Haven and
John Hsu, Chemist III, Florida Department of Citrus,
The Processed Foods Inspection Laboratory of the U.S. Department
of Agriculture in Winter Haven agreed to aid the Florida Department
of Citrus in their program for the nutritional study of processed
citrus. The USDA's part in the program was to draw a sample of 6/6
ounce cans of Frozen Concentrated Orange Juice from each processor
each week of production. The samples were brought to the laboratory
in Winter Haven. One sample was retained in the USDA Laboratory for
Thiamine and Niacin analyses and the other five were turned over to
the Department of Citrus for their analyses.
Thiamine and Niacin were determined by microbiological assay.
Thiamine was determined by the method of Sarett and Cheldelin, J.
Biol. Chem. 155, p 153 (1944) using Lactobacillus fermenti. Niacin
was determined by the A.O.A.C. method, 7th Edition, p 782 (1950),
using Lactobacillus plantarum.
Over 200 determinations were made on both vitamins on samples
collected in March, April and May, 1973. There appeared to be no
significant differences in the ranges of amounts between these
months. The samples showed a thiamine range of 0.23 to 0.46 milligram
per 100 grams of FCOJ or 8.2-16.3% U.S. RDA per 6 fluid ounce serving
of reconstituted juice. Niacin ranged from 0.65 to 0.95 milligram per
100 grams of FCOJ or 1.7 to 2.5% U.S. RDA.
Thiamine was determined, by the Department of Citrus, by thiochrome
fluorescence using the method described in the AOAC, llth Edition, p 774
(1970), with some minor modifications for analysis of FCOJ. The proce-
dure is very sensitive and quite accurate with reproducibility to
within 2.5%. Experiments with added known amounts of thiamine have
shown recovery to be better than 97%. The results of analyses of
approximately 100 FCOJ samples collected from the industry have shown
a range of 0.21 to 0.31 milligram per 100 grams of FCOJ or 7.5 to 11%
U.S. RDA per 6-fluid ounce serving of reconstituted juice.
10:20 A.M. ORANGE JUICE CAROTENOIDS CONTRIBUTING TO VITAMIN A ACTIVITY
S. V. Ting, Research Biochemist, Florida Department of
Citrus and I. Stewart, Biochemist, University of Florida
Agricultural Research and Education Center, Lake Alfred.
The vitamin A activity of orange juice is contributed by certain
carotenoids. These carotenoids are provitamins A which form retinol,
or vitamin Al, when acted upon by certain enzymes in the digestive
system of animals. Until now free retinol has not been found in
plant materials. Of the many carotenoids occurring in citrus juices,
the alpha- and beta-carotenes and the monohydroxy carotenoid,
cryptoxanthin, are the only ones known to have provitamin A activity.
The alpha-carotene and cryptoxanthin have only one-half the vitamin
potency of the beta-carotene.
In the Nutrition Labeling Act, the Recommended Daily Allowance
for vitamin A is 5000 IU (1 International Unit = 0.6 microgram of
beta-carotene), or 3.0 mg of beta-carotene. Using the method of the
Association of Vitamin Chemists, the total carotene, which includes
both the alpha- and beta-carotenes, averaged slightly less than 2%
RDA in 6 fluid ounces of reconstituted concentrate. The method does
not measure the cryptoxanthin in the sample.
Using a high speed liquid chromatographic technique, cryptoxanthin
was successfully separated from the carotenes, other monohydroxy
carotenoids and dihydroxy carotenoids. It was also found that
cryptoxanthin as well as the total carotenes and total carotenoids in
the juice of 'Valencia' oranges increased with the maturity of the
fruit. Since the amount of cryptoxanthin in orange juice is quite
substantial as compared with the carotenes, its inclusion in the
provitamin A analysis would greatly increase the vitamin A value of
the orange juice.
10:35 A.M. HIGH SPEED LIQUID CHROMATOGRAPHY ITS POSSIBILITIES
FOR ANALYSIS OF WATER SOLUBLE VITAMINS R. W. Wolford,
Research Chemist and J. N. C. Hsu, Chemist III, Florida
Department of Citrus, Lake Alfred.
The oldest of the chromatographic methods, column liquid chro-
matography, currently is experiencing a renaissance which is re-
establishing its reputation as one of the most useful techniques
available to the scientist. Although liquid chromatography predates
gas chromatography by almost a half century, the liquid chromatographic
technique has often been relegated to a "last ditch status" because of
inconvenient and time consuming efforts usually accompanying this
methodology. The rebirth of interest in liquid chromatography with
achievement of rapid separations has been due in large measure to the
improvement in column efficiency and the use of high mobile-phase
velocities. Among varied applications, high speed liquid chromato-
graphy presents a fast and reliable method for analysis of both fat-
and water-soluble vitamins, and is being extensively investigated at
this laboratory. A brief discussion of the instrumentation, techniques
employed, and some analytical results will be presented.
11:10 A.M. PROGRESS IN THE NUTRITIONAL RESEARCH PROGRAM AT THE
UNIVERSITY OF FLORIDA, COLLEGE OF MEDICINE Richard R.
Streiff,. Associate Professor of Medicine, University of
Orange juice has been evaluated as a source of potassium by Dr.
Homer Knizley. All data collected to date, using 21 week study
periods in 10 controls and patients indicates that OJ is an excellent
source of potassium and can maintain a patient's potassium level in
the normal range although he is taking antihypertensive medicines which
increase potassium loss. The patients were followed for weight gain,
fluid retention and other untoward effects of orange juice but none
were noted. Analysis of the data will be completed shortly. A
manuscript is now being written.
Studies designed to evaluate the bioavailability of folic acid
and vitamin C in orange juice are being carried out as a cooperative
project by Dr. Cerda and Dr. Streiff. Preliminary data from multiple
studies on ten volunteers confirms that orange juice is an important
nutritional source of these 2 vitamins.
Assays for pyridoxine indicate that a declarable quantity of
this vitamin is found in orange juice. Pantothenic acid also occurs,
but in lesser quantities.
11:30 A.M. CITRUS SPECIALTY PRODUCTS A REPORT OF PROGRESS -
R. J. Braddock, Assistant Food Scientist, and J. W.
Kesterson, Chemist, University of Florida Agricultural
Research and Education Center, Lake Alfred.
The various specialty and by-products produced and sold by the
Florida citrus industry are citrus pulp, essential oils, limonene,
molasses, frozen juice sacs, candied peel, marmalade base, brined
peel, bioflavonoids and pectin pomace. These products are estimated
to be worth approximately $55 million, or 30-35 cents per box,
annually to the citrus industry.
In addition to the above listed products, processing of citrus
seeds into seed oil, meal and hulls could realize $11 million annually
for the industry, or about 7 cents/box of fruit.
Analyses of peel oil content for various citrus cultivars,
averaged for four seasons, showed a grand total of 82 million pounds
present for the quantity of fruit processed (165 million boxes 1972
season). Actual oil production figures show that only 32 million
pounds of cold-pressed oil and limonene were produced, a yield of
Juice sacs are a potential air pollutant from citrus feed mills.
Besides being sold as a frozen product, they can be recovered and
dried for potential uses in food products such as dry beverage mixes
and thickening agents. The flavedo from citrus peel can be processed
into purees for sherbet, or may be a source of natural carotenoid
pigments. Naringin can be extracted from grapefruit peel and used as
a bitter flavor for certain beverages. It is also possible to process
naringin and hesperidin into synthetic sweeteners.
11:50 A.M. PHYSICAL AND CHEMICAL CHARACTERISTICS OF COMMERCIAL
ORANGE JUICE PRODUCTS PACKED DURING THE 1972-73 SEASON -
R. W. Barron, Chemist II, Florida Department of Citrus,
CHILLED ORANGE JUICE
Thirty-two chilled orange juice samples were examined for flavor
during the 1972-73 citrus season. Samples were collected on approxi-
mately the 1st of each month from 2 to 7 plants, represented at any
one collection period, out of 8 plants in Florida. Chilled orange
juices were graded by an Agricultural Research and Education Center
taste panel. Flavor scores were based on a 9-category hedonic scale
ranging from like extremely to dislike extremely. The flavor scores
fell in 5 categories, like moderately, like slightly, neither like
nor dislike, dislike slightly and dislike moderately, and the samples
that fell in these categories were 9, 79, 9, 3 and 0% respectively
for the 1972-73 season; 13, 64, 23, 0 and 0% for the 1971-72 season;
and 17, 50, 22, 9 and 2% for the 1970-71 season.
FROZEN CONCENTRATED ORANGE JUICE
During the 1972-73 citrus season a total of 211 samples of com-
mercial FCOJ were examined for flavor and color. In addition,
physical and chemical analyses relating to juice quality were conducted.
Samples were collected semi-monthly during the season from 4 to 21
plants represented at any one collection period out of 22 plants in
Florida. Reconstituted juices were graded for flavor by an Agricultural
Research and Education Center taste panel. A 9-category hedonic scale
which goes from dislike extremely to like extremely was used for this
study. The flavor grades for samples in the "like very much", "like
moderately", "like slightly", "neither like nor dislike", or "dislike
slightly" category were respectively 5, 60, 29, 6, and 3) for the
1972-73 season; 8, 62, 26, 3 and 1% for the 1971-72 season; and 4,
60, 30, 5 and 1% for the 1970-71 season.
A Hunterlab Citrus Colorimeter was used to measure color differ-
ences in the reconstituted juices. Frequency distribution of Citrus
Red and Citrus Yellow values were lower this season than last season
and than the 1970-71 season.
12:10 P.M. LUNCH
Chairman: Omer R. McDuff, Director of Research and Quality Control,
Adams Packing Association, Auburndale, Florida.
1:30 P.M. FURTHER PROGRESS ON GRAPEFRUIT BITTERNESS STUDIES -
P. J. Fellers, Food Technologist, Florida Department of
Citrus, Lake Alfred.
The primary objective of the grapefruit bitterness study this
year was the determination of practical flavor acceptability thresholds
for bitter components in grapefruit juice. An earlier test had shown
consumers in Washington, D. C. to be much more tolerant toward grape-
fruit bitterness than Center personnel. Consequently testing of
samples possessing higher bitterness levels were necessary to establish
the desired thresholds. Subsequently 12 large packs of ca.ned single
strength grapefruit juice having four bitterness levels, with three
Brix/acid ratios within each bitterness level, were prepared. The
varying bitterness levels were achieved through the addition of 0, 7,
14 and 21% by weight of a very bitter, Center-made grapefruit pulp
wash to good Florida commercial frozen concentrated grapefruit juice.
The Brix/acid ratios of 8, 9.5 and 11 were achieved by adjusting with
sucrose and/or citric acid.
The Washington, D. C., USDA Consumer-Type taste panel under the
direction of Mr. Jon Weimer were supplied samples for flavor evaluation
Panelists rated samples on a 9-category hedonic scale. The following
table shows the mean hedonic scale preference rating for all samples
where "3" = dislike moderately; "4" = dislike slightly; "5" = neither
like nor dislike; "6" = like slightly; and "7" = like moderately:
Approx. Bitterness Level
Brix/ 0% Added Pulp Wash 7% Added P.W. 147o Added P.W. 21% Added P.W.
acid 2.5 ppm Limonin 10 ppm Lim. 17.5 ppm Lim. 25 ppm Lim.
ratio 660 ppm Naringin 1000 ppm Nar. 1280 ppm Nar. 1560 ppm Nar.
8.0 5.99* 5.60 4.86 3.81
9.5 6.72 5.83 5.01 4.35
11.0 6.78 6.01 5.07 4.40
Each value represents the mean for 72 taste panelists.
An analysis of variance of the data showed that each bitterness
level was highly significantly different (.001 probability level)
from every other bitterness level within each Brix/acid ratio.
Futhermore, there was a highly significant linear drop in preference
ratings with successively higher levels of bitterness within each
Brix/acid ratio. There was no significant effect of ratio on flavor
preference but a trend showed preference for higher ratio juices at
every bitterness level. Another taste testing of these same 12
samples is currently underway by the Washington, D.C. group to test
specifically for possible ratio effect.
These data showed once again a much more tolerant group in
Washington, D.C. as regards bitterness in grapefruit juice as compared
with Center personnel who rated the bitter samples generally a point
or more lower than the Washington people. As much as 12.5 ppm limonin
in conjunction with 1,100 ppm of naringin were tolerated by the
Washington group as a whole before they graded the samples below
about 5.5 or into the "neither like nor dislike" category, which is
at best a very marginal flavor quality category. The data show very
clearly the deleterious effect of adding very bitter grapefruit pulp-
wash to good grapefruit juice.
One of the foremost problems in the whole grapefruit bitterness
project has been in securing reliable data on limonin content in
samples. At least two new methods have been developed recently to
determine limonin and another is being worked upon, but agreement
between methods still is far from precise.
1:45 P.M. PARTICLE SIZE ANALYSIS A NEW TOOL FOR CITRUS JUICE
DEFINITION B. S. Buslig, Research Biochemist, and
R. D. Carter, Research Chemist, Florida Department of
Citrus, Lake Alfred.
Preliminary observations from the Juice Definition Program (JDP)
samples indicate that the Coulter Particle Size Analyzer may be a
useful tool in evaluating differences between juices obtained by some
processing variables, such as soft and harsh extraction and various
methods of finishing.
Orange juices, diluted with an electrolyte solution, were examine
with the Model T Coulter Counter. In this instrument, the size
classification of particles is established by the change of resistance
caused by particles passing through an orifice between two electrodes.
The particle volumes are proportional to the magnitude of resistance
change. The pulses obtained this way are classified into size ranges
with a 15 channel analyzer. At the same time for population density
counts in each size range, the number of pulses are recorded by the
instrument. The data obtained this way were processed by a program in
the Wang 720C calculator to indicate total particle numbers in each
size range, volume distribution of particles, and a graphic display of
the latter parameters.
According to the results so far, the particle distributions in
the 1.26-3.17 i range show maxima, with the actual peak varying from
6-14% of the pulp volume counted. Statistical analysis of the particle
size vs. flavor and other analytical variables may be necessary to sho;
important differences between types of processing factors.
2:00 P.M. ABSORPTION AND EMISSION CHARACTERISTICS OF ORANGE JUICES
AND RELATED PRODUCTS D. R. Petrus, Chemist III, and
M. H. Dougherty, Research Engineer II, Florida Departmen'
of Citrus, Lake Alfred.
The combined visible and ultraviolet absorption and fluorometric
emission characteristics of orange juices and related products will be
presented. The absorption and emission curves for the three varieties
'Hamlin', 'Pineapple', and 'Valencia' are similar except for intensi-
ties. Therefore a shift in wavelength, unusual change in intensity or
absence of absorption or emission maxima may be indicative of devi-
ations from the pure product.
The products to be discussed will include the following: the
three varieties 'Hamlin', 'Pineapple' and 'Valencia' orange juices, a
commercial frozen orange concentrate and pulpwash concentrate, a
commercial orange drink and two synthetic orange drinks.
2:30 P.M. OBJECTIVE PREDICTION OF FCOJ FLAVOR, A TWO YEAR
REGRESSION ANALYSIS P. J. Fellers, Food Technologist,
and B. S. Buslig, Research Biochemist, Florida Depart-
ment of Citrus, Lake Alfred.
Thirty samples of reconstituted juices from commercial frozen
concentrated orange juice (FCOJ), obtained during the 1972-73 season
were examined for 32 different characteristics. The analyses included
flavor, sinking pulp, Brix, titratable acidity, Brix/acid ratio, oil,
serum viscosity, total aldehydes, oxygenated terpenes, chemical oxygen.
demand (COD), glycosides, limonin, pH, cloud, color values from the
Hunterlab citrus colorimeter: Citrus Red (CR), Citrus Yellow (CY) and
Color Number; water-insoluble solids, alcohol-insoluble solids, sucrose,
total sugars, protein, water-soluble pectins, sodium hydroxide-soluble
pectins, total pectins, ash, potassium, sodium, calcium, magnesium,
formol numbers and chloramine T value. The latter two analyses were
added this year.
Flavor, in each case, was determined by a panel of 10 experienced
tasters, evaluating the juices on a 9-point hedonic scale. All other
analyses were performed by established analytical techniques by various
investigators on the staff of the Department of Citrus and Agricultural
Research and Education Center.
Once again, the General Electric (G.E.) time-sharing computer
system was used for the statistical analysis. Correlations of individual
variables with flavor, as well as an overall multiple correlation
equation, were obtained as the year before. In addition another
multiple correlation, combining the data from last year and the current
results, was run. The system permits only 25 independent variables,
therefore multiple runs through the system were required.
The results presented will include equations and fit from the
current year, last year and the combination of the two years.
2:50 P.M. DISTRIBUTION OF 14C-ETHYLENE AND THE INCORPORATION OF
RADIOCARBON IN 'VALENCIA' ORANGES AFTER EXPOSURE TO
14-C-ETHYLENE J. F. Fisher, Research Chemist, Florida
Department of Citrus, Lake Alfred.
Externally applied C-ethylene was found to distribute throughout
the internal environment of the orange. Radiocarbon was incorporated
into the ether soluble material and fractions containing amino acids,
organic acids, and the 80% ethyl alcohol soluble carbohydrates. The
greatest activity was in the ether soluble and organic acid fractions.
Citric acid was isolated and found to be radioactive. This radio-
labeled citric acid indicates the oranges' ability to utilize ethyl-
ene as a source of carbon. The amount of 14C found distributed
throughout the orange represented about 0.2% of the applied
This is believed to be the first published report of the
incorporation in oranges of carbon from ethylene.
3:10 P.M. THE AUTOMATIC BRIXOMETER PROGRAM J. G. Blair, Research
Engineer III, and R. W. Wolford, Research Chemist,
Florida Department of Citrus, Lake Alfred.
The development of an automatic method to read the Brix of single
strength citrus juices within the range of 5 to 20 degrees has been
progressing for the last 10 years. An automatic Brix blender is used
in most concentrating plants for mixing evaporator pump-out with
stabilized cutback juice just prior to canning. It was therefore only
logical to have the manufacturer of this blender supply a unit for
reading Brix in the State Test Rooms. So far they have been the major
supplier of experimental refractometer units, up to what might be
called the "fifth generation". The refractive index (relative 7, 120
and 170 Brix) standardized solutions, reported at this meeting last
year, were employed in the initial calibration of the 12 Electron
Machine Corporation Model SSR-70L Refractometers that were tested
under field conditions during the 1972-73 season. However, only the
mid-range refractive index solution at a relative 120 Brix was required
for monitoring the calibration setting of each instrument on a one time
per day basis. The statistical analyses of the results from these
field tests, indicate that only a few were producing satisfactory
results on all types of fruit. In view of this, Electron Machine
Corporation designed a new unit which will cause the old one to become
obsolete. Preliminary tests on this new model SSR-72 Refractometer
were encouraging so one was purchased for experimental use. In
addition to the above, an entirely different system of measuring Brix,
by specific gravity weighing, has been further developed. Boththe
preliminary laboratory as well as the field testing indicate that
this is a potentially practical alternate method of determining Brix
in the State Test Rooms.
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, Betty Murphy, Mary Smith, Alice Barber,
Margaret Swift, Sharon Lovejoy, Faye Martin, Bernice Mercer, Joe
Collins, Fred Givens, Roy Albright, Harold Walker, Terry Longtin
and to all other personnel of either the University of Florida
Agricultural Research and Education Center or the Florida Department
of Citrus who helped in many and various ways.