Program for ... annual Citrus Processor's Meeting.
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Title: Program for ... annual Citrus Processor's Meeting.
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Creation Date: 1972
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Full Text


We extend to you a cordial welcome to this Twenty-third Citrus
Processors' Meeting, sponsored jointly by the Florida Department of
Citrus Scientific Research Department and the IFAS Agricultural
Research and Education Center at Lake Alfred.
Our objectives in these meetings are to keep citrus processors up-
to-date on our research results, and to listen carefully to the
processors' comments and ideas about what our program should be.
It is difficult to keep up to date and relevant in a small research
group. Opportunities to modernize or change direction are greatest
when new personnel enter the research group. We hope to keep closely
in touch with the processing industry, so that our decisions about
change in direction will be most likely of success

Herman J. Reitz
Agricultural Research and
Education Center, Lake Alfred

**** ********************* ****

The Department of Citrus staff joins the Institute of Food and
Agricultural Sciences in welcoming you to the Annual Processors'
Meeting. We have a number of interesting reports for you this year
including the results of our work on grapefruit bitterness, the
second year's data from our Juice Definition Program and the status
of the Automatic Brixometer.
We of the Department of Citrus again express our deep appreciation
for the continuing help and cooperation extended to us by IFAS
Agricultural Research and Education Center during the past season.

John A. Attaway
Scientific Research Direct
Florida Department of Citrus


University of Florida
Agricultural Research & Education Center
P. 0. Box 1088
Lake Alfred, Florida 33850

9:00 A.M. Registration

9:30 A.M. Welcome
Herman J. Reitz
Director, Agricultural Research & Education Center
Lake Alfred, Florida.

Chairman: Art Mathias, Chairman, Florida Citrus Research Council.

PRODUCTS James F. Fisher, Research Chemist, Florida
Department of Citrus, Lake Alfred.

A new procedure for the assay of microgram quantities of limonin in
grapefruit juice will be presented. This determination of limonin is
more objective than earlier methods.
Limonin was separated from grapefruit juice and quantitated fluro-
metrically as follows:
1. Grapefruit juice was extracted with chloroform.
2. The chloroform was removed and the residue chromatographed
on a short aluminum oxide column employing a chloroform/
benzene solvent system. The column retained the compounds
which were more polar than limonin.
3. The eluate, containing the limonin and less polar compounds,
was treated with aqueous sodium hydroxide. This converted
the limonin into the di-sodium salt of limonoic acid which
was extracted into the aqueous phase leaving the unwanted
less polar material remaining in the chloroform layer.
4. The di-sodium salt of limonoic acid was reconverted to limonin
by acidification of the aqueous phase followed by chloroform
extraction. This afforded limonin in the chloroform layer.
5. The isolated limonin was measured fluorometrically in concen-
trated sulfuric acid.
6. The micrograms of limonin were read from a standard curve.
The mean of five determinations on a grapefruit sample was 4.06 ppm
with a range of from 3.84 to 4.36 ppm. This difference of 0.52 ppm is
good precision for this type of procedure.

R. J. Braddock, Assistant Food Scientist, and J. W.
Kesterson, Chemist, University of Florida Agricultural
Research and Education Center, Lake Alfred.

Tocopherol (vitamin E) analyses were performed on a variety of fresh
and processed citrus fruits. A sensitive, gas chromatographic tech-
nique was employed to quantitatively determine the tocopherol content
of these products. The technique involved the identification and esti-
mation of the volatile trimethylsilyl ethers of individual tocopherols
present in a sample. The tocopherol content measured as mg total
tocopherol/100 ml juice, was as follows for the various samples: 1)
reconstituted commercial frozen concentrated orange juice (13 samples,
0.01-0.14), 2) glass-pac single strength orange juice (4 samples, 0.1-
0.2), 3) glass-pac single strength grapefruit juice (4 samples, 0.1-
0.2), 4) canned single strength orange juice (2 samples, 0.2), 5) canned
single strength grapefruit juice (2 samples, 0.2), 6) fresh-squeezed,
unheated 'Valencia' juice (4 samples, 0.3-0.8) and 7) fresh-squeezed,
unheated 'Duncan' grapefruit juice (4 samples, 0.15-0.3). Peel oil and
seed oil from fresh fruit were much higher in tocopherols than the
juices, generally having values in the range 5-30 mg tocopherols/100 gm
sample. For purposes of comparison, the tocopherol content of cotton-
seed oil is about 50-60 mg/100 gm and wheat germ oil is in the range
150-200 mg/100 gm.
These results indicated that citrus juices were not good dietary
sources of vitamin E, primarily because of low concentration. Compari-
sons between fresh and processed juices also showed that processing
significantly decreased the amounts of tocopherols present.

M. D. Maraulia, Chemist II, Florida Department of Citrus,
Lake Alfred.

During the 1970-71 citrus season, nine fruit samples of 'Valencia'
and 'Pineapple' oranges were extracted with commercial equipment using
a harsh, destructive squeeze, and, both hard and soft "commercial"
squeezes. Following extraction, the pulpy juices were finished using
both an FMC Model 35 screw-finisher and a Westphalia, Model SA7, pilot
plant size centrifuge. The two finishing methods were compared on the
basis of single-strength finished juice quality and on that of the high
Brix concentrates in regard to flavor, cloud, bottom pulp, viscosity
and color, together with finished juice yields. The over-all quality
of the centrifuge-finished juices was dependent for the most part on
the degree of finishing as compared with screw-finishing using standard

screen and settings. When juice yields by both finishing methods were
matched to within approximately 1% yield, the overall quality of the
centrifuge-finished juices was slightly higher. High Brix concentrates
prepared from these juices using both a hard and soft squeeze were con-
siderably less viscous than those prepared from the screw-finished
juices. Some quality factors for pulp-free, high ratio, Valencia con-
centrate, prepared by centrifuge finishing, are also discussed.

ROOMS R. W. Wolford, Research Chemist, and J. G.
Blair, Research Engineer, Florida Department of Citrus,
Lake Alfred.

Investigations leading to the development of a stable chemical
solution for use in the routine standardization of Electron Machine
Corporations (EMC) SSR-70 Refractometers were conducted in cooperation
with personnel of the Florida Department of Agriculture, Division of
Fruit and Vegetable Inspection during the latter part of the 1971-72
processing season. The commercial EMC units which have been in
operation in State Test Juice Rooms in 12 processing plants this season
have had as the only standardizing media fresh juice, or juice plus con
centrate, to provide an approximate 100 Brix span from 70 to 170 Brix.
The many inherent problems encountered using juices of variable con-
sistency for absolute calibration of the digital readout system within
the tolerance limits of + 0.05 Brix made it evident that some appro-
priate external standard having physical characteristics similar to
orange and/or grapefruit juices was required.
Intensive research concurrent with optical and electronic adjust-
ments to the Department of Citrus EMC Refractometer in this laboratory
resulted in the development of a solution, or series of solutions, of
specific refractive indices containing cloud and color (optional) and
having a specific gravity closely comparable to that of citrus juices.
Laboratory comparisons between the Department of Citrus EMC Refracto-
meter and an updated commercial EMC system, both calibrated using the
new refractive index solutions, showed excellent correlation with Brix
hydrometer values (within 0.050 Brix) on fresh and processed single
strength juices. The refractive indices (relative 0 Brix) standards
were found to be applicable for instrumental calibration of several
commercial systems at the EMC plant. The useage of the standards for
electronic adjustment, linearity checks, and simulated juice analyses
by the manufacturer and test room operating personnel was successful.
Statistical data developed during laboratory and commercial testing in
the 1971-72 season will be presented.


PACKED DURING THE 1971-72 SEASON R. W. Barron, Chemist
II, Florida Department of Citrus, Lake Alfred.

A total of 203 samples of commercial FCOJ were examined for flavor
and color during the 1971-72 citrus season. In addition, physical and
chemical analyses relating to juice quality were conducted. Samples
were collected semi-monthly during the season from 10 to 20 plants out
of 22 plants in Florida. Reconstituted juices were graded for flavor
by an Agricultural Research and Education Center taste panel. The per-
centages of Flavor grades for samples in the "like very much", "like
moderately", "like slightly", "neither like nor dislike", or "dislike
slightly" category were respectively 8, 62, 26, 3, and 1 for the 1971-
72 season; 4, 60, 30, 5, and 1 for the 1970-71 season; and 1, 24, 55,
19, and 1 for the 1969-70 season.
Color differences in the reconstituted juices were measured with a
Hunterlab Citrus Colorimeter. The average Citrus Red and Citrus
Yellow values were higher this season than last season and about the
same as for 1969-70.

Research Biochemist, John A. Attaway, Scientific Research
Director, James G. Blair, Research Engineer, Robert D.
Carter, Chemist II, Paul Fellers, Food Technologist, and
James F. Fisher, Research Chemist, Florida Department of
Citrus, Lake Alfred.

A new study of the relationship of the major bitter principles of
grapefruit juice and juice products to quality has been initiated. The
purpose of this program is to determine the desirable levels of bitter-
ness in grapefruit products and to develop objective methods for evalu-
ating grapefruit flavor through analysis for bitter constituents.
The 2 known major chemical constituents which contribute to bitter
taste in grapefruit juice are limonin and naringin. The latter is the
principal flavanone glycoside of grapefruit. It is generally believed
that limonin is much more bitter than naringin and makes a major con-
tribution to poor fruit quality in the early weeks of the season.
Efforts have been made to develop a bitterness index by adding the
ppm limonin, multiplied by an appropriate factor, to that of naringin
to give a single value as suggested by Mr. Robert Kilburn of Citrus
World, Inc. This approach was not completely successful due to dis-
agreement among investigators concerning the magnitude of the factor,
to a lack of reliable methods for accurate analysis for limonin, and

to the question of correlation between the Davis test for flavanone
and the actual naringin content. The relationship of limonin values
to flavor reported in this study can only be considered approximate,
however, juices with a high limonin content and a high bitterness
index frequently were given lower flavor scores by the taste panel at
the Center.
An important part of this study involved 2 experiments in a plant
with a commercial pulp-wash unit. One experiment was conducted in
mid-December and the other in late April. In the December experiment,
reconstituted pulp-wash concentrate contained up to 20 ppm limonin
while that prepared in April contained 0-5 ppm. Some early-season
commercial grapefruit pulp-wash contained as much as 29 ppm limonin.
Centrifuging these samples lowered the limonin level, however, in the
April experiment, the effect of centrifuging on limonin content of
concentrated pulp-wash was inconclusive. Unprocessed early season
juice showed about 5-7 ppm limonin while none could be detected in un-
processed late season juice.
A wide variety of commercial grapefruit juice samples, concentrated,
chilled, and canned, from Florida markets, as well as from 4 major
National markets, were analyzed for bitter principles. The results
were compared with flavor panel scores expressed via a 9-point Hedonic
Scale. Sugar-add samples were excluded. No direct correlation could
be demonstrated, but it was found that reconstituted grapefruit juice
and chilled grapefruit juice received substantially higher scores than
canned juice.
An extractor study conducted in late December using light, medium,
and hard squeeze settings with both 'Duncan' and 'Marsh' varieties,
demonstrated that limonin values were highest with the hard squeeze
regardless of variety. In this study, it was also found that the
'Duncan' juice contained less limonin than the 'Marsh' juice. Finisher
tests with these juices gave inconclusive results regarding the re-
duction of bitterness.
It was generally observed that when grapefruit juice had a high
Brix and Brix/acid ratio, the taste panel was less likely to discrimi-
nate against it on the basis of bitterness than when it had a low
Brix and Brix/acid ratio.
To provide insight regarding the bitterness level preferred by con-
sumers, grapefruit juice with 4 different levels of bitterness were
provided to the U.S.D.A. consumer-type taste panel in Washington. It
was found that the U.S.D.A. tasters were much more tolerant toward
bitterness than the Center's panel. As a consequence, an extensive
central location taste test is planned for Winter 1972-73 to get more
information regarding the degree of bitterness the grapefruit juice
consumer will accept.

Howard J. Connolly, International Marketing Manager,
Florida Department of Citrus, Lakeland.

The greatest stimulus to the consumption of processed citrus juices
occurred during and immediately after World War II. It was the result
of the massive shipments of juices made to Europe during 1943-44, and
then subsequently, the availability of canned citrus juices, that were
available through the period of postwar reconstruction.
In the late 1940's the citrus industry in Florida found themselves
with overproduction in canned citrus juices and recognizing the
potential that the European market offered took positive action in
trying to develop sales for canned juices. This effort was supple-
mented by the efforts of the then Florida Citrus Commission, which
established an office in Europe and generated a program of generic
advertising and promotion. This kind of activity continued well into
the middle 1960's, and the one problem that had not been completely
satisfied was the continuity of supply that was and is necessary to
sustain any marketing activity.
In the mid-1960's the market development program, a joint effort of
the Foreign Agricultural Service, the Florida Department of Citrus and
the foreign importer was initiated and has since been identified as
the Three Party Program. While at the outset it primarily supported
single strength juice in glass and some retail-size frozen concentrated
orange juice, as competitive activity increased, there was the recog-
nition of a market change. The Florida effort was faced with lower
prices from other citrus-producing areas of the world, which brought
about the recognition of the need for introducing bulk frozen concen-
trated citrus juices for reconstitution for the European marketing
In the last three years, a major transition has been made in many
of the Western European countries with regard to citrus juices. They
are now assuming a regular place in the eating habit of the European
consumer, and because of the readily available channels of distri-
bution offered by many large dairies which are reconstituting bulk
frozen juice into single-strength in paper cartons, we now have the
two ingredients necessary for increased consumer activity. These are
availability, because of good distribution, and competitive pricing
due to the program of reconstitution from bulk.

12:15 P.M. L------------------------------------
12:15 P.M. LUNCH


1:30 P.M.

Marvin Walker, Vice Chairman, Florida Citrus Commission.

John A. Attaway, Scientific Research Director, Rodger
W. Barron, Chemist II, James G. Blair, Research
Engineer III, Bdla S. Buslig, Research Biochemist,
Robert D. Carter, Chemist II, Marshall H. Dougherty,
Research Engineer II, Paul Fellers, Food Technologist,
James F. Fisher, Research Chemist, Elmer C. Hill,
Research Bacteriologist, Richard L. Huggart, Chemist
III, Donald R. Petrus, Chemist III, S. V. "Jerry" Ting,
Research Biochemist, Florida Department of Citrus and
Alvfn H. Rouse, Chemist, Agricultural Research and
Education Center, Lake Alfred.

In a study to determine the typical chemical and physical juice
characteristics of orange juice in the 1970-71 season, 33 separate,
analyses were made on two series of juices prepared periodically in
the pilot plant. One series had been produced using extremely harsh
squeezing which would generally be considered unacceptable in
commercial practice, while the other was prepared in a manner approach-
ing that used in commercial production. These two juices were found
to be widely divergent in many of their characteristics.
During the past season 31 analyses were used to study another two
sets of juices prepared with two extractor settings less different
than those used in the previous year. Both of these settings were
within the bounds of commercial production practices. In addition,
juices were prepared using the "State Test-House" extractor. Compari-
son with the latter series of juices will be reported later by James
G. Blair.
The following table shows a comparison of the conditions of the
juice extractor setting for the past two seasons using 1/8" beam

1970-71 Season 1971-72 Season
Squeeze Squeeze
Harsh Soft Hard Light

3" 3" 3" 4" 3" 4"

090" 040" 040" 040" 040" 040"
1" WR 1" SR 1" WR i 1/4"WR 1" SR 1 1/4"SR
ID and/or Restrictor
7/16"LR 1/2"BM 7/16LR 1/2"LR 5/8"BM 9/16"LR

Upper Cutter

Note: WR Window Tube
SR Split Ring (No window)
LR Long Restrictors
BM Bell Mouth
L Long
S Short

In a separate series of tests, the 1970-71 soft squeeze settings were
repeated periodically to provide a comparison of the fruit from the two
years. The long upper cutter and the larger diameter strainer tube of
the light squeeze were found to give comparatively lower yields.
A uniform representation of the three varieties, 'Hamlin', 'Pine-
apple' and 'Valencia' was used this past year, while only one compara-
tive run had been made with the 'Hamlin' variety in 1970-71 because of
problems encountered in starting up the program.
The State test juices were finished periodically as will be discussed
in detail in the next presentation. This work indicated the need for
inclusion of finisher setting variables in the experimental design for
the 1972-73 Juice Definition Program.
A table of maximum, minimum and average values for each parameter in
the 1971-72 program is provided and a comparison made with the correspond
ing values in the 1970-71 program. A table of correlation coefficients
for each variety will be presented for the first time this year. Using
the correlation coefficients, a Multiple Regression Flavor Prediction
Equation (MRFPE) was developed by means of a computer program. The
agreement of actual flavor scores and the flavor scores predicted by
the equation compares favorably with a similar equation developed from
the 1970-71 data.

In an effort to make a practical, commercial application of the
MRFPE 30 samples of commercial FCOJ were analyzed and correlation
coefficients developed. This will be presented in the paper by
Fellers and Buslig.
A number of new types of analyses, are being evaluated using the
juices stored throughout the season. The most promising of these
analyses will be added to the program for next year.

REGRESSION EQUATION Paul J. Fellers, Food Technologist,
and Bdla S. Buslig, Research Biochemist, Florida Depart-
ment of Citrus, Lake Alfred.

The reconstituted juices of 30 commercial frozen concentrated orange
juice samples collected during the 1970-71 citrus season were analyzed
for 30 different characteristics. The analyses included flavor, sink-
ing pulp, Brix, acid, Brix/acid ratio, oil, serum viscosity, total
aldehydes, oxygenated terpenes, Chemical Oxygen Demand (C.O.D.), total
glycosides, limonin, pH, cloud, color values from the Hunterlab Citrus
Colorimeter as follows: Citrus Red (CR), Citrus Yellow (CY), and
Equivalent Color Score (ECS); water insoluble solids, alcohol insolu-
ble solids, sucrose, total sugars, protein, water soluble pectins,
sodium hydroxide soluble pectins, total pectins, ash, potassium,
sodium, calcium and magnesium.
Flavor was determined in each case by 10 experienced taste-panelists
evaluating samples on a 9-point hedonic scale. All other determinations
were performed by established analytical procedures. None of the
samples were found to contain limonin, subsequently this variable was
omitted from the statistical analysis.
The General Electric (G.E.) time-sharing computer was utilized in
analyzing the data. Correlations of individual variables with flavor
yielded a maximal correlation coefficient of -0.529 with total glyco-
sides. Such a correlation explained only about 28% of the flavor
variation, therefore further analysis considering multiple variables
was employed. The G.E. Statistical Analysis System used a stepwise
linear multiple regression in which a maximum of 25 independent variables
were permitted at one time.
The system automatically selected a combination of 6 variables
giving the highest degree of significance contained in the data.
These 6 variables yielded the following regression equation:
(FL) = 1.076(AC) + .956(TS) .676(NA) + .915(CA) + .02(TP) -
.045(GLY) 4.626
FL = flavor AC = % acidity CA = calcium
TS = total sugars TP = total pectin
NA = sodium GLY = total glycosides
r(correlation coefficient) = .904


Using the above equation, flavor scores were calculated and the table
below shows a comparison between actual and predicted scores. (The
equation predicted approximately 81.5% of the variation in flavor.)

Flavor Scores of Samples
Observed Predicted Observed Predicted
6.7 6.6 6.1 6.4
6.4 6.4 7.0 6.8
6.1 5.9 7.0 6.8
6.2 6.4 6.4 6.6
7.1 7.0 7.1 7.2
6.3 6.1 7.6 7.5
7.0 6.9 5.5 5.4
6.7 6.8 5.8 6.2
6.6 6.6 6.3 6.6
6.6 6.8 7.0 6.7
5.1 5.4 6.1 6.6
7.5 7.2 6.9 6.7
6.8 6.6 6.5 6.3
6.9 7.0 6.5 6.9
6.3 5.8 5.4 5.4

Further statistical analyses, excluding the previous six variables,
showed no other statistically significant components in either linear
or 2 different curvilinear regression systems.


2:45 P.M. GRAPEFRUIT POUNDS-SOLIDS James G. Blair, Research
Engineer III, Florida Department of Citrus, Lake Alfred.

The Inspection Service has been voluntarily fulfilling an increasing
number of requests for pounds of solids measurements on grapefruit.
This very likely will result in a regulation making the measurement of
grapefruit Pounds-Solids a mandatory procedure for all processing
plants requesting State Certification.
Several years ago evaluations of extractors were made for the
purpose of selecting a machine for the Pounds-Solids measurement of
oranges. Limited tests were run on grapefruit but no in-depth study
was carried out because at that time there was little interest in
Pounds-Solids measurement for this fruit.


Two years ago the industry requested that a program be started with
the objective of improving the current methods of measuring grapefruit
Pounds-Solids. So far the efforts on this program have been confined
to the modification of the present official extractor to obtain more
equitable yields between the Marsh and Duncan varieties. The increase
in squeezing pressure which worked well for oranges, was not sufficient
for grapefruit especially when only the 5-inch cup was used for all
fruit. Therefore, it was necessary to broaden the testing procedures
to include the use of both the 4- and 5-inch cups as well as different
strainer tubes and settings. The results of these new developments
are encouraging and it appears that progress is now being made toward
accomplishing the objectives.

1970-71 AND 1971-72 SEASONS Robert D. Carter, Chemist
II, A. H. Rouse, Chemist, S. V. Ting, Research Biochemist,
and Rodger W. Barron, Chemist II, Florida Department of
Citrus and Agricultural Research and Education Center,
Lake Alfred.

Orange pulp wash concentrate and samples of non-pulp wash orange
concentrate evaporator pumpout were compared using 33 analytical pro-
cedures of which only 5 showed significant differences. Twenty-three
midseason samples and twenty-nine'Valencia' samples were collected
from seven commercial concentrate plants during the 1970-71 and 1971-
72 seasons.
Striking differences between pulp wash and non-pulp wash concen-
trate samples were found in the values obtained for serum viscosity,
water-insoluble solids, protein, water-soluble pectin, and oxalate-
soluble pectin (1970-71 only). Regression equations were developed
using results for the above constituents. The data points are dis-
played graphically below and the equations will be discussed in the

52 SAMPLES-7 PLANTS-1970-71 and 1971-72 SEASONS
SVP W 1 _VPO M=Midseason
VPW VPO V = Valencia
M P W M PO po=Pumpout Conc.
PROTEIN ( g/100ml X 100) PW=Pulpwash Conc.
VPO overlap
0 5 10 15 20 25



0 50 100 50-200 25

.150 200


0 50



3:15 P.M. FLAVOR COMPARISON James G. Blair, Research Engineer
III, Florida Department of Citrus, Lake Alfred.

The Juice Definition Program (JDP) has been in operation at the
Center for two complete seasons. Juices for this program were ex-
tracted at different pressure settings. It was found that a change
in these settings usually affected both yield and flavor. To pro-
vide a basis for comparing JDP yields with those attained in
commercial operations, an official State Test Room Extractor was used
as a control. Juices from the program had flavor scores ranging from
"dislike extremely" for samples prepared by a harsh squeeze to "like
moderately" for samples prepared using a soft squeeze. Surprisingly,
the taste panel expressed a preference for juices from the State Test
Room Extractor over any of the juices tested. Some juices had a
relatively high pulp content which normally detracts from flavor.
However, some consumers prefer juice with pulp, particularly the
floating type. The pulp from the State Test Extractor is of this
type. The characteristics of the pulp have a definite bearing on
flavor and consumer acceptance. Some primary differences between the
commercial extractors used and the State Test House Extractor include
the hole size in the strainer tube, the internal diameter of the
orifice tube, the machine speed and the length of stroke. Finishers
were adjusted to yield juices with the same Quick Fiber value regard-
less of extractor setting, therefore it was assumed that the finisher
did not represent a variable.

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,
Florence Wolff, Margaret Swift, Sharon Lovejoy, Roger Waters, Joe
Collins, Fred Givens, Roy Albright, Harold Walker, Vernon Rhoades,
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.