Summary of citrus processing and by-products research projects.
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Title: Summary of citrus processing and by-products research projects.
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Creation Date: 1962
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Year Ending June 30, 1962

Florida Citrus Experiment Station and Florida Citrus Commission
Lake Alfred, Florida


State Project 607 J. W. Kesterson and R. Hendrickson

A study on the chemical composition of Valencia orange oil as related to
fruit maturity by gas-liquid chromatography has shown the following constituents
to be presents alpha-pinene, Beta-myrcene, d-limonene, octanal, methyl hepta-
none, nonanal, methyl heptenol, octyl acetate, citronellal, decanal, linalool,
octanol, linalyl acetate, nonyl acetate, undecanal, nonanol, geranyl acetate,
decyl acetate, decanol, dodecanal, citral, terpineol, carvone, neryl acetate,
nerol and geraniol.

Seven components o- .ocanira nonanal, decanal, linalool, undecanal, do-
decanal and terpineol -- accented for approximately 75 per cent of the total
composition of the terpeneless oil fraction. One interesting facet of this work
is the presence of citronellal in Florida Valencia orange oil. To date this
aldehyde has not been reported in California Valencia oil and may well be used
as a further means by which oils from these different areas can be distinguished
from each other. Gas chromatographic data show that the chemical composition of
the oils varied with frait maturity and these changes probably account for the
differences in flavor.

An investigation has been initiated to determine the significant differences
between seed oils from 39 lemon varieties. Those variables under study are:
number of seeds per fruit, percentage of moisture in seeds, percentage of wet
seeds in each variety, index of refraction, iodine number and fatty acid com-

Citrus oils produced commercially by the screw press and FMC-In-Line
Extractor were evaluated for quality during the 1961-62 season. The aldehyde
content of early and midseason oils were below normal, whereas the physicochemi-
cal properties of Valencia oils were considered normal.


State Project 646 R. Hendrickson and J. W. Kesterson

Work is in progress to determine the optimum maturity for the commercial
extraction of hesperidin from Valencia fruit. Starting each season with small
fruit, somewhat larger than one-inch, extractions were made at regular intervals
until the fruit had reached maturity.

Among the important conditions for effecting optimum recovery of hesperidin,
small fruit demanded highly alkaline extraction conditions by virtue of the
greater protopectin content, while with more mature fruit these same conditions

Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred Florida.
10/2/62 FWW


became less desirable. Highest purity of crude product on each extraction date
was usually coincidental with the conditions leading to maximum yield.

The results of this past season gave further evidence that peak yields were
obtained by processing small immature whole fruit having an equatorial d.irmeter
between 1.5 to 2.0 inches. Maximum yield of hesperidin under optimum conditions
has increased in each of the last three respective seasons from 77 to 91 to 156
pounds per acre of trees, but this has in part been caused by improved -eislds of
fruit per tree, The greatest loss of product occurred in the isolation stage and
this loss became proportionately larger with fruit of advanced maturity. Further
substantiation was obtained that the percentage of hesperidin in Valencia oranges
decreases logarithmically as fruit size increased, but that this linear relation-
ship was shifter toward lower percentages with fruit from trees o:f higher


State Project 817R W. F. Newhall

The study of the preparation and fungicidal properties of new amino alcohol
and quaternary ammonium derivatives of d-limonene has been continued. The ter-
tiary amino alcohol, 2-piperidyl-8(10)-p-menthen-l-ol, has been prepared and
converted to the quaternary compound by reaction with methyl iodide. Tests con-
ducted in cooperation with Dr. Ro Patrick have shown that the introduction of
the piperidyl group causes a decrease in fungicidal activity compared to
p-menth-8-en-l-ol, 2-dimethylamino methiodide, reported previously (Annual
Report, 1961)

The acetate and o-methoxy-benzoate esters of 2-dimethylamino-8(10)-p-
menthen-l-ol and the benzoate and o-metho.ybenzoate esters of 2-dimethylamino-
l-p-menthanol have been prepared for biological screening as possible hypoten-
sive agents or central nervous system depressants. These h new esters are high-
boiling liquids which were purified and characterized through their crystalline,
picrate salts.

The reaction of trans-2-amino-6(O1)-p-menthen-l-ol with cyanogen bromide has
afforded an unsaturated, crystalline hydroxy-cyanamide analogous to the saturated
hydroxy-cyanamide reported previously (Annual Report, 1961)o

Py thermal degradation, 1(l-1ydroxy-p-menth-2-yl) -2-thiourea (Annual Report,
1961) has been converted to a new hydroxyisothiocyanate. This conversion proceeds
smoothly by loss of ammonia at 160C, under high vacuum.


State Project 880 G. E, Coppock and P. J. Jutras

Increased citrus production together with a shortage of suitable and willing
labor have created a need for improved equipment and methods for picking citrus

Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida,
10/2/62 FWW

Oscillating Air-Blast Machine. A machine to produce an oscillating air-
blast was constructed to study the possibility of using this principle for
harvesting citrus fruit. Tests performed in mature groves of different varie-
ties indicated that air velocities from 8,600 to 10,000 feet per minute at the
source were necessary for fruit removal of 40 to 95.6 per cent at a travel rate
of 1/4 mph. Higher removals were obtained at oscillation rates of 50 to 80
cycles per minute. This principle offers a means of harvesting fruit by moving
continuously along the tree row; however, the leaf shredding caused by high air
velocities may introduce a horticultural problem.

Tree Shaker. Tests in Hamlin and Pineapple orange groves of an inertia
shaker with a h-inch stroke and an unbalanced weight of 85 Ib. resulted in fruit
removals of 60 to 85 per cent. By increasing the stroke to 6 inches an increased
removal of 18 per cent was obtained in Valencia oranges. Trials in Marsh and
Duncan grapefruit resulted in 85 to 90 per cent removal. The performance of a
cable shaker in Valencia oranges was inferior to that of the inertia shaker on
average size trees. The tree shaking principle seems especially promising in
that it can be adapted to a variety of tree sizes and shapes. Larger and faster
fruit removal is needed for the success of this principle.

The merits of both fruit harvesting principles may be influenced greatly by
their effects on the life and future productivity of the trees.


State Project 921 Roger Patrick and S. K. Long

Pilot-plant 2,3-butylene glycol fermentations using Aerobacter aerogenes 199
have been developed employing a 20-gallon "Cavitator"' unit. Aeration and stirring
were more efficient and reproducible in this unit than in the laboratory model,
resulting in consistently high yields of glycol and low sugar residues. Glycol
yields ranged from L.5 to 4.9 per cent, with unfermented sugar amounting to 1.9
to 2.5 per cent. Aeration at a rate of 0.2 cubic feet per minute was essential
only during the early stages of the fermentation (24 hours), although stirring
was continued. Very high aeration and stirring rates were unsatisfactory due to
more rapid decrease in pH and difficulty in foam control.

Bacillus polyyxa B-510 stock cultures were found to lose fermentation abil-
ity after being carried on artificial media over extended periods. Complete
inactivation of these cultures by lyophilization appears to be the solution to
this problem.

Further work on the problem of extracting 2,3-butylene glycol from the fer-
mentation beer indicated that the only method satisfactory in all respects is
steam-stripping under high pressure. A unit has been designed and will soon be

1 Registered trademark of Yeomans Brothers Company.

Florida Citrus Experiment Station
and Florida Citrus Conmission,
Lake Alfred, Florida.
10/2/62 FWW

in operation. Solvent extraction and direct distillation in vacuo were success-
ful in removing glycol but were unsatisfactory due to cost or difficulties in
clean-up operations.

A chromatographic study of the amino acid content of citrus press liquor and
molasses is in progress. The results obtained indicate that a major limiting fac-
tor in fermentation of these substrates is a deficiency in free amino acids.

Continued study on the polymerization of 2,3-tbutylene glycol and d-limonene,
singly or combined, to yield alkyd resins, indicates that this may be a useful
outlet for these compounds. The physical state of the resins ranged from semi-
solids to very hard, brittle solids.


State Project 944 L. C. Knorr, M. F. Oberbacher and H. M. Vines

During the early stages of this project, in an effort to obtain preliminary
information quickly, lemon selections were topworked to 30-year-old grapefraiu
trees. Yield and disease data are still being collected from this 520-tree trial,
but before recommendations can be made as to the best varieties to plant, it ~ll
be necessary to single-bud the better selections onto commercial root0st;cks and
to evaluate them for resistance to shell bark. To this end, a field trial of 22
of the most promising selections budded to rough lemon has beer established at
Avon Park in cooperation with Stokely-Van Camp, Inc.

Investigations contirne into the cause of rumple, which trouble appeared
again in the 1961 season. Rumple was present in 32 of the h0 varieties under
test at the Minute Maid planting in Avon Park.

Curing of Sicilian variety of lemons over a longer period of time, July 24
to September 25, indicated that the earlier fruit needed more time to degree at
60F. Time of curing ranged from 31 to 16 days. Precuring at a very low temp-
erature, 32F, then transferring to normal curing temperatures, increased the
time necessary to degree by the amount of time the fruit were held at the low

Bleaching of lemons (h 3/4 oz. HTH per 5 gal. of water) did not have any
effect on changing the color of scars on the fruit.

A survey of the fresh fruit qualities of the varieties in Minute Maid's
block was made.


State Project 1019 A. H. Rouse, C. D. Atkins and E. L. Moore

Evaluation was made of the pectins from the component parts of Valencia
oranges prepared during the 1959-60 and 1960-61 seasons. Ranges of values for
jelly grade of pectins in the peel, membrane, and juice sacs were from 190 to

Florida Citrus Experiment Station
and Florida Citrus Conmission,
Lake Alfred, Florida.
10/2/62 FWW

219, 286 to 363, and 198 to 240, respectively. Other corresponding values were
jelly units from 44 to 61, 97 to 123, and 40 to 50; methoxyl contents from 8.8
to 10.5 per cent, 10.0 to 10.7 per cent, and 7.9 to 10.0 per cent. Pectins from
the seeds had no jelly grade.

Basic information was obtained for the second year on the distribution of
pectinesterase activity (PE) and the 3 pectic fractions in the component parts
of Pineapple oranges at various stages of maturity. Oranges were picked each
month from September to May. The fruit was separated into peel, membrane, juice
sacs, seeds, and juice. Maximum PE activity in these parts was 20.5, 25.7, 57.8,
3.5, and 0.4 units per g fresh tissue, respectively. Largest quantities of water-
soluble pectins in each component part of Pineapple oranges, as listed above,
were 868, 1,438, 387, 2,102, and 48 mg per 100 g fresh tissue; ammonium oxalate-
soluble pectins were 2,872, 1,369, 587, 856, and 13 mg per 100 g fresh tissue;
sodium hydroxide-soluble pectins or protopectins were 2,178, 2,566, 672, 1,198,
and 10 mg per 100 g fresh tissue.

Highest PE activity was found in the juice sacs. The peel and membrane
shared equally in containing the most total pectin during the 9 months of
Pineapple orange maturation.


State Project 1033 R. W. Wolford, J. A. Attaway and
G. E. Alberding

The flavor of orange juice has been studied objectively through analyses of
recovered volatile materials. Concentrated natural orange essences, obtained
commercially, and specially recovered volatile components from juices of estab-
lished varieties of oranges were used in these investigations.

Retention temperature studies employing programmed temperature gas chroma-
tography (PTGC) and 2 principal column phases, DEGS and Carbowax 20 M, supplied
tentative identification and peak assignments for 43 compounds.

Comparison of analyses of flavor and aroma components of Hamlin, Pineapple,
and Valencia orange juices revealed no significant qualitative differences using
either thermal conductivity or flame ionization detection systems. Some relative
quantitative compositional differences between juice varieties were observed with
advancing maturity. Analyses of simulated commercially extracted juice, peel oil-
free juice, their respective juice essences, and peel oils from each variety
showed compositional differences. Certain constituents were directly related to
the juice and others to the peel oil.

Paper chromatographic properties of 7 classes of urethan derivatives have
shown o-nitrophenyl, m-nitrophenyl, and p-phenylazophenylurethans to be satis-
factory in analyses of alcohols. In concert with PTGC and infrared, 1-propanol,
1-butanol, 3-hexenol, and 1-octanol were identified. Also, strong evidence for
1-nonanol, and 1-decanol in orange essence was obtained. Acetic and butyric

Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
10/2/62 FWW


acids were identified as their p-phenylazophenacyl esters and ammonium salts by
paper chromatography. Ethyl butyrate and d-limonene were identified in orange
essence by PTGC retention temperatures and infrared analyses. The former, not
previously reported, is an ester of major proportion in orange juices.


State Project 1037 M. H. Dougherty

The activated sludge system, incorporating the "Cavitator'l as the aeration
chamber, has been kept in operation treating citrus waste water. The volume of
waste being treated was held constant at 30 gal. per day but the concentration of
the waste was varied from 0.136 per cent to 0.214 per cent total solids. The
volume of air injected into the aerator was held constant at 0.30 cubic feet per
minute and the amounts of inorganic nutrients added to the waste were varied
from 10 ppm nitrogen and 34 ppm phosphate to none of either.

The system did an excellent job of treating all concentrations of waste
within the above limits. However, maximum sludge production was obtained when
waste concentrations ranged from 0.185 per cent to 0.244 per cent total solids
and the inorganic nutrient level was held at 10 ppm of nitrogen and 10 ppm of
phosphate. Under these conditions, from 20 to 24 per cent of the solids in the
waste being treated were recovered as excess sludge.

A new criterion for determining when sludge removal from the system should
be inaugurated was used during the latter portion of this year. It was found
that the level of settled sludge in the final clarifier rather than the volume of
sludge in the aerator was a better indication of when excess sludge was

This project is being terminated with this report.

1 Registered trademark of Yeomans Brothers Company, manufacturer.


State Project 1073 M. D. Maraulja, R, W. Barron, R. W. Olsen,
Ro L. Huggart and E. C. Hill

The flavor, stability, and color were determined for 195 samples of
commercial frozen orange concentrate processed during the 1960-61 season. These
samples were collected from 23 plants with the assistance of personnel of the
Agricultural Marketing Service, USDA, Winter Haven. These samples were graded
by a taste panel and flavor grades of "good" and "fair" were given to 43 and 56
per cent, respectively; 1 per cent of the samples were graded "poor". After
storage for 96 hours at 40 F, undesirable definite or extreme clarification was
found in 0.5 per cent of the orange concentrates; 9.8 per cent of the samples
showed undesirable clarification after storage at 80F for 24 hours. Semi-gels

Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
10/2/62 FWW

occurred in 4 samples after the abuse test at 40F. A Hunter Color Difference
Meter was used to determine color differences in the orange concentrates. Semi-
monthly average Hunter "a" values (redness) ranged from 3.9 to 8.5; "b" values
yellownesss) from 32.8 to 34.4; and "Rd" values (lightness) from 22.1 to 25.7.


State Project 1109 C. D. Atkins, E. L. Moore and A. H. Rouse

The purpose of this investigation is to determine the effect of the use of
different component parts of citrus fruit and processing procedures on the
characteristics and quality of frozen citrus concentrates.

Separation of the component parts of Valencia oranges from Station groves
yielded peel, rag, juice sacs, and seeds. These parts were ground and washed
with isopropyl alcohol. A shelf dryer and a vacuum dryer were constructed to
remove the isopropyl alcohol and complete drying to a low moisture level. Each
part was ground individually in a Wiley mill and screened. Sufficiently large
samples were retained on the 150-, 65-, and 35-mesh screens for use in preparing
extracts and for addition to juices.

A Study was begun of the effect of particle size on the yield of pectic
constituents, and on the turbidity and viscosity of water extracts. Total
pectins in the peel, rag, and juice sacs were highest for the largest particle
size. Water-soluble pectin varied in the peel from 48 to 49 mg per g; in the
rag from 63 to 80 mg per g; and in the juice sacs from 58 to 62 mg per g. The
same irregularity was noted for the oxalate-soluble pectin content. Sodium
hydroxide-soluble pectin, showed a definite trend to be greater in the larger
particles of all 3 portions of the oranges. Further investigation into the
characteristics of these fruit parts is necessary before inclusion in juices
prior to concentration and storage.

The high-density single-stage evaporator (Arm. Rept. 1959, p. 254) was con-
verted to a low temperature unit. This evaporator will permit preparation of the
concentrates required for this study and also for recovery of the condensate and
included volatile materials from juices during evaporation (State Project 1033).


Utilization of Freeze-Damaged Oranges in Frozen Orange Concentrate. -
Properties of orange juices were determined after extraction from frozen fruit.
These fruit were frozen on trees by Dr. Hendershott using a portable freezing
chamber (Ann. Rept. 1961, p. ). Frozen oranges that were picked from trees
and also dropped fruit were used.

Frozen Pineapple oranges picked from a tree, 1 day after freezing at 20"F
for 4 hours, contained juice having soluble solids of 12.1 Brix, 0.90 per cent
total acid, as citric, and a Brix/acid ratio of 13.4. Juices from fruit, that
dropped from this tree from February 8 to 14, inclusively, and remained on the

Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
10/2/62 FW


ground from 2 to 16 days, varied in soluble solids; however, total acid ranged
from 0.76 to 0.55 per cent and the Brix/acid ratio from 16,1 to 21.1.

Valencia oranges were frozen at 20"F for 4 hours on 5 trees from February
27 to March 3, inclusively. A sample of unfrozen fruit was picked from each
tree just prior to freezing. The frozen oranges were picked 3, 4, 5, 6, and 7
days after freezing. Changes occurred in the juices 3 days after freezing of
the fruit and became greater as the time between freezing and picking was in-
creased. Data in Table show ranges for some characteristics of juices from both
unfrozen and frozen fruit. After freezing of the oranges, the acid content of
the juices decreased, Brix/acid ratio increased, relative serum viscosity in-
creased, pulp content increased, redness (Hunter "a" value) increased, and the
lightness or "milky appearance" (Hunter "Rd" value) increased.

Packs of frozen orange concentrate were made from both Parson Brown and
Pineapple oranges, which were frozen on trees during December, January, and
February. Analyses of these products have not yet been completed. (F. W.
Wenzel, R. W. 01sen, R. L. Huggart, and R. W. Barron)

Microbiology of Frozen Oranges. The microbiological examination of juice
from oranges frozen on trees by means of a portable freezing unit (Ann. Rept.
1961, p. ) was continued. The juice from individual oranges remaining on
trees after freezing was plated on orange serum agar. Aseptically extracted
juice from 40 Parson Brown oranges, remaniing on a tree 14 and 20 days, were
free from microorganisms with the exception of 1 orange which had a very low
count of 2,400 colonies per ml of juice. Pineapple oranges were examined 12
times over a period of 120 days. The juice from each of 240 oranges was free
from microorganisms with one exception; this juice, examined 99 days after
freezing, had a plate count of 2,610,000. Valencia oranges were picked 12
times during 105 days. Of 240 fruit examined, the juice from 1 orange picked
after 56 days had a count of 5,800; A count of 84,000 was found in the juice
from another orange which had remained on the tree for 98 days. Thus for 2
seasons, only 1 orange with juice highly contaminated and 1 orange with moder-
ate contamination were found after examination of 869 frozen oranges picked
from trees.

Fruit which had dropped to the ground after freezing were examined in the
same manner. Care was taken to select only those fruits which were free from
obvious damage by microorganisms. Parson Brown oranges were examined after
remaining on the ground 8, 13, 17, 18, 19, and 23 days. The 140 dropped Parson
Brown oranges examined included 20 which were infested with microorganisms. The
plate counts of these oranges ranged from 33,000 to 355,000,000 per ml of juice,
with 17 of the 20 juices having counts of over 1 million. Dropped Pineapple
oranges were examined after being on the ground for 6, 7, 20, 21, and 25 days,
Of 120 oranges, juice from only 2 fruit, which had been on the ground 25 days,
had significantly high microbial plate counts of 212,000,000 and 57,000,000.
Counts of 13,000 and 41,500 were obtained from juice of 2 other oranges after

Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
10/2/62 FWW

Table. Ranges for characteristics of Valencia orange juices from unfrozen and frozen fruit
picked from the same trees immediately before and 3 to 7 days after freezing

Brix unfrozen

10.20 -10.7
9.7 -10.7

Total acid-% unfrozen

Brix/acid ratio unfrozen
S frozen

pH unfrozen
" frozen




Relative viscosity unfrozen
it frozen

Hunter "a" value unfrozen
I" frozen

Hunter "b" value unfrozen

Hunter "Rd" value unfrozen


-5.2 to -h.h
-3.9 to -3.2



Pulp-% by vol. unfrozen
T" " frozen


Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
10/2/62 FWW

21 and 25 days on the ground, respectively. Dropped Valencia oranges were ex-
amined after 13, 21, 23, 2L, 26, 27, and 28 days on the ground. Only 1 of the
140 oranges was infested with microorganisms having a plate count of 5,500,000
per ml of juice after being on the ground 26 days. (E. C. Hill)

Freeze Project. The primary objective of this project is to obtain in-
formation on the effect of freezing temperatures on the fruit and trees of
Citrus species.

A total of 31 citrus trees were exposed to low temperature during the
winter of 1961-62. Little or no tree damage occurred on Marsh grapefruitt
Dancy tangerine, Parson Brown, Pineapple and Valencia orange exposed to 2! +
5$F for periods of 6 to 8 hours, except in the case of 3 trees of Parson
Brown which were wet at this temperature and therefore killed back to the
large scaffold limbs. At this temperature and duration, there was no damage
to the fruit of Marsh grapefruit. Dancy tangerine fruit was partially frozen,
resulting in a softening at the stem-end and the fruit dropping from the tree.
Orange fruits were all frozen, resulting in a loss of flavor, lowering of acid
and sugar, and a general insipid flavor developing 3 to 5 days after freezing.

The results of freezing on the quality of fruit for processing is reported
elsewhere in this report. (C. H. Hendershott)

Factors Affecting Stability of Frozen Concentrated Orange Juice. Further
study was made on the effect of pectinesterase (PE) activity, quantity of pectic
substances, and degree of concentration on the stability of frozen concentrated
orange juice when it is subjected to temperatures above OF.

Concentrates were prepared from Pineapple orange juices obtained by using
finisher head pressures of 5 to 20 psig and heated to 200F prior to concen-
tration to completely inactivate PE. Cutback juice of known PE activity was
added so that the resulting 42 Brix concentrates contained 0.5, 2.0, and 3.5
units per gram of concentrate. Corresponding packs of 50.7 Brix concentrates
were prepared similarly from the same juices. The 42 and 50.70 Brix concen-
trates with 0.5 PE unit of activity did not lose cloud after 132 days at 40F
storage; those with 2.0 PE units required 33 and more than 130 days, respectively,
to develop develop definite clarification; and those with 3.5 PE units required
8.5 and 67 days, respectively, before definite clarification was detectable,

Also concentrates were prepared from Pineapple orange juice in which similar
PE activity was present during concentration. The cutback juice was completely
inactivated of enzymic activity. In these packs, both the L20 and 50.7* Brix
concentrates were less stable during 40F storage than those products to which PE
activity was added only in cutback juices. Also varying finisher pressures used
in preparing the juices definitely affected the stability of these products when
stored at o40F.

Data from all packs indicated that as finisher pressures increased from 5 to
20 psig, the water-soluble, ammonium oxalate-soluble and sodium hydroxide-soluble
pectins increased in the juices. (E. L. Moore, A. H. Rouse and C. D. Atkins)

Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred Florida.
10/2/62 W


Firming of Canned Grapefruit Sections with Calcium Saltsl Two series of
packs were prepared commercially in February and March to determine the effect
of calcium salts on the firming of canned grapefruit sections. Each series
consisted of grapefruit sections packed in either water, syrup, Sucaryl and
water, calcium lactate and syrup, or calcium chloride and syrup. These packs
were examined initially and will again be examined after storage for 4 and 8
months at 80*Fo (R. Wo Olsen, R, W. Barron, and R. Lo Huggart)

1 Aided by grants from American Maize Products Company and Abbott Laboratories.

Consumer Surveys. At the request of the Florida Citrus Commission, a
series of canned orange juices and canned grapefruit juices were prepared in
order that the Bureau of Special Surveys, USDA, can conduct a taste preference
survey for citrus juices in West Germany. These packs consisted of 1,000 cans
each of orange juice with 10 to 1, 13 to 1, and 16 to 1 Brix/acid ratios. The
grapefruit juices were prepared with 7 to 1, 9 to 1, and 11 to 1 ratios.

Several consumer acceptance tests of a canned grapefruit drink (Ann.
Rept. 1955, p. 210) have been conducted by Dr. William E. Black of the Florida
Citrus Commission with extremely favorable results. Consequently, arrangements
have been made to commercially pack this drink for market tests in Evansville,
Indiana, and Columbus, Ohio, (Ro W. Olsen)

Aluminum Analysis of Concentrated Citrus Juice. An aluminum determination
described by Wetlesen and Omang (Anal. Chim. Acta 24: 294, 1961) using the re-
agent stilbazo and the method of Yuan and Fiskell TAgr. Food Chem. 7: 115, 1959)
using aluminon were compared on perchloric acid digests of orange juice concen-
trate. The method using stilbazo produced no differentiation between standards
up to 20 ppm aluminum. The method of Yuan and Fiskell, with slight modification,
produced satisfactory calibration curves down to 1 ppm aluminum. Using twice the
recommended gum arabic reduced the tendency for the aluminon lake to adhere to
the beaker after the heating procedure. Also, heating for 10 minutes rather than
5 permitted greater reduction in volume and, therefore, more thorough rinsing of
the beaker when transferring the aluminon lake to volumetric flasks. (E. C. Hill)

Improved Methods for Determination of Pounds Solids. The purpose of this
project is to develop accurate and stable methods for determining the pounds
solids particularly for oranges delivered to the processor. The program is
divided into 3 categories, namely, the selection of the sample, the extraction
of the juice from this sample and the analysis of the juice for Brix and acid.

A bulk fruit handling system which will be used to study sampling methods
has been constructed at the Station. Existing extractors have been modified and
new extractors have been obtained for further study on improving machines for
extraction. Automatic methods to perform the manual functions now done by the
State inspectors are being considered and several are presently in the process
of development. Some sampling and extracting tests have been run.

Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
10/2/62 FWW


So far the selection of the sample has been restricted to a hand selected
random sample for the tests run at the Station and the conventional mechanical
sampler for the tests run at the various canning plants. In addition to the
normal error in selecting a true random sample, considerable error has been
experienced in our method of sizing and counting. As a further check, the
weights as well as the numbers of fruit in each size are now obtained. The
average weights apparently give more reliable information than the percentage
of each size determined from counting. Comparison tests on the Brown and FE
extractors show that there is practically no difference in their performance
when operated under controlled conditions. For samples that had average weights
from 0.427 to 0.530 Ib. per fruit the average yield was Brown, 57.7 per cent;
FMC, 57.9 per cent; and the maximum variation, 2.6 and 2.8 per cent,
respectively. (J. G. Blair)

Specific Gravity Measurement and Its Use in Estimating Pounds-Solids of
Oranges. The use of specific gravity measurement as a means of determining
fruit quality is desirable since the sample is not destroyed and a much larger
sample can be used. In both the Pineapple and Valencia oranges, highly signifi-
cant regression was found between the specific gravity and the pounds-solids of
the fruit. However, there was a difference in the specific gravities between
the two varieties and among the various sizes. There was a negative correlation
between the size of the fruit and its specific gravity. In Pineapple oranges
the average specific gravity ranged from 0.919 for the size 126 fruit to 0.959
for the size 288 fruit. These values for corresponding sizes in Valencia were
0.946 and 0.980, respectively. The high specific gravity was found to be
mainly due to higher juice content and lower peel content of the fruit.
(S. V. Ting)

Relation of Size of Fruit to Weight, Specific Gravity, Diameter, and Volume
and Refractive Index of Juice of Oranges. Results of preliminary measurements
upon Valencia oranges show relationships between size and weight of fruits, size
and volume of juice, and size and refractive index. Relationship of size to
diameter/height ratio was very slight, while the relationship with specific
gravity (w/v) was intermediate. Thus, some promise that size and weight, or
size and specific gravity separations would improve the juice volume and quality
of citrus has been shown. (W. G. Long and F. W. Hayward)

Fruit Physiology. Work continued with metabolic studies with the isolation
of citrus mitochondria. Only slight activity could be obtained in isolated cases
although the same techniques utilized on beets gave excellent results. Addition
of supernatant to mitochondrial suspensions occasionally produced a limited up-
take of oxygen. Thorough investigations by spectrophotometric and manometric
methods of this phenomenon has established the fact that the enzyme, ascorbic
acid oxidase, is present in young orange fruit tissue. This activity decreased
on a fresh weight basis as the size of the oranges increased to about 3 centi-
meters in diameter, The presence of ascorbic acid oxidase was verified by pH
optimum, fractionation with a;monium sulfate, inhibition by cyanide and
diethyldithiocarbamate at 10- M concentration.

Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
10/2/62 FWW


A spectrophotometric method of assay for ascorbic acid oxidase was also
devised. (H. M. Vines and M. F. Oberbacher)

Organic Acids in the Juice Vesicles of Hamlin Oranges. The organic acids
in the juice vesicles of Hamlin oranges at different stages of fruit development
were separated by ion exchange and paper chromatography. Eight acids were ob-
served on the paper chromatograms. Five of these acids, namely citric, malic,
quinic, succinic, and an unknown acid occurred in sufficiently high amounts in
various stages of fruit development to be measured quantitatively.

Quinic acid concentration decreased sharply from 1.8 milliequivalents (m.e.)
per 100 grams in May to about 0.1 m.e. per 100 grams in September and remained
relatively unchanged thereafter. The absolute amount of quinic acid per fruit
showed a slight decrease throughout the season. Malic acid concentration also
decreased sharply from May to September. This decrease was found to be due to
the dilution effect when the size of the fruit was increasing since the absolute
amount of malic acid per fruit during that period varied little. During the
period of ripening, the absolute amount of malic acid per fruit increased while
the rate of fruit size increase slowed down, resulting in a rapid increase f"
malic acid concentration.

The concentration of citric acid was the highest in June and July and de-
creased through October. The rapid accumulation of citric acid in each fruit,
however, occurred during the period between May and September and became l-s
pronounced thereafter. The decrease in the concentration of citric acid in the
juice vesicles during this time was entirely due to the increase in fruit weight.

Succinic acid was tentatively identified by its position in the elution
from the column and by its Rf value on the paper chromatogram. Its concen-
tration increased from May to July but decreased rapidly through October. No
significant change of succinic acid was found between October and December when
the concentration varied between 0.3 and 0.4 m.e. per 100 grams of juice
vesicles. The unknown acid is yet to be identified. There seemed to be no
consistent trend of this acid concentration with fruit development. (S. V. Ting)

Chromatography, Spectroscopic and Polarographic Analyses. The work re-
ported below was done in support of projects in citrus nutrition, plant pathology,
by-products, entomology and processing.

Paper chromatography was used for 6,145 samples for the following research
groups: flavor group, 86 per cent; fruit handling, 13 per cent; and 1 per cent
for the combined groups of nutrition, entomology and by-products.

Infrared absorption spectra were made on 773 samples. Forty-five per cent
of these were for the flavor study group, 37 per cent for fruit handling, 7 per
cent for by-products, 5 per cent for nutrition, 4 per cent for pathology and 2
per cent for entomology.

Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
10/2/62 FWW


Included in the work for the flavor studies was a catalogue of C-1 to C-12
of 6 different types of urethanes and a catalogue of di nitro phenyl hydrozenes.

Ultraviolet absorption spectra were made on 78 samples. Of these, 52 per
cent were run for by-products, 20 per cent for nutrition, 19 per cent for fruit
handling, 5 per cent for flavor studies, 2 per cent for entomology and 2 per
cent for processing.

Polarograms were run on 288 samples. Of these 255 were
of zinc. Experimental copper runs were made on 33 samples.
since it would not repeat results of other experiments. (G.

for nutrition studies
This work was dropped
J. Edwards)

Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
10/2/62 FWW