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: 1954
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Year Ending June 30, 1954

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

During the 1953-54 citrus season, 265 packs of concentrated citrus juice
and 31 packs of single-strength canned juice were prepared in the Station pilot
plant. In processing these packs 2690 boxes of citrus fruit were used consisting
of Hamlin, Pineapple and Valencia oranges, Dancy tangerine, seedy and seedless
grapefruit, limes and lemons.

Clarification and Gelation in Concentrated Citrus Juices.- Four-fold and
6-fold Valencia orange concentrates were prepared from one lot of fruit to deter-
mine their relative stability at storage temperatures of -8PF., 200F., 400F. and
60F. The 6-fold concentrates of approximately 590Brix were prepared from con-
centrates of 81.50, 71.50 and 610Brix to study the effect of using various amounts
of cut-back juice. Peel oil was added to a calculated level of 0.015 percent by

A slight taste preference was shown initially for the samples with the most
cut-back juice. The 4-fold concentrate and 6-fold concentrate cut-back from
81.5oBrix were preferred but not differentiated. Least preference was expressed
for the sample that contained only added peel oil and a very small amount of
cut-back juice. As the juices aged, preference, if any, shifted to the concen-
trates containing the least amount of cut-back.

The 4-fold concentrate began to show flavor and cloud deterioration and
gelation after three weeks storage at 20oF., and was commercially unacceptable
in one week at higher temperatures. The 6-fold concentrates were stable for
one week at 600F. and four weeks at 400F. The 6-fold concentrates, stored at
200F., were found to be good after nine months and showed only slight degradation
at one year.

Periodic microbiological examinations of the concentrates were made using
dextrose tryptone agar, pH 7.0, and orange serum agar, pH 5.6. The 4-fold
concentrate stored at -80F. showed an apparent count increase of 8 percent after
the first month when plated on dextrose tryptone agar, but showed a loss of 23
percent on orange serum agar. At the close of the three-month period, micro-
organisms as shown on both media had declined 91 and 90 percent respectively.
When stored at 20CF. and 400F., decline was 77 to 87 percent and this continued
until at the end of the three-month period it was 90 to 98 percent. At 600F.,
spoilage occurred in all of the products before or by the end of three months.

All concentrates showed a greater decline in microorganisms at 200F. and
400F. than at -8OF. during the first month, but by the end of three months
there was very little difference.

Florida Citrus Experiment Station and
Florida Citrus Commission, Lake Alfred, Fla.
531-10/12/54-E L

Organisms increased in all samples at all temperatures after a six-month
storage period. The number of organisms generally declined in all samples after
nine months. After twelve months there was little change in numbers among
samples stored at 20aF. Samples stored at -8@F. showed a rapid decline between
the nine and twelve month analyses, except in the 6-fold product made from 81.50
Brix concentrate, plated on dextrose tryptone agar, which showed an increase.
Since it is unlikely that organisms grow at low temperatures, increases in numbers
at -80F. must be apparent rather than real. The groups of organisms in the
concentrates that were plated on orange serum agar did not die off at the same
rate during storage as those that grew on dextrose tryptone agar.

Frozen concentrates were prepared from Pineapple and Valencia oranges and
from Duncan grapefruit by processing juices having a pulp content of 2 to 26
percent by volume. Chemical and physical changes were measured prior to con-
centration, after processing, and after storage of the concentrate at 80aF.
for 24 hours. Water-insoluble solids in concentrated citrus juices made from
two seedy varieties, Pineapple orange and Duncan grapefruit, increased during
processing of the juices with pulp levels of 10 and 17 percent or greater
respectively. No similar increase was found in concentrates made from the
relatively seedless Valencia orange. During storage water-insoluble solids
increased in all of the concentrates. Pectinesterase did not diminish signifi-
cantly during concentration of the juices from the two orange varieties, but the
activity was lowered during processing of Duncan grapefruit juices. There was
a loss of pectinesterase activity in all samples after storage. In general, the
water-insoluble pectin decreased and oxalate-soluble pectin increased during
processing and after storage of the concentrates. Hydrolysis of protopectin
occurred in Duncan grapefruit concentrates stored at elevated temperature, but
it did not take place in the orange concentrates. Clarification and gelation
increased during processing of Pineapple orange and Duncan grapefruit juices as
percentages of pulp became greater, while no change took place when Valencia
orange juices were concentrated. After storage for 24 hours at 800F., extreme
clarification was evident in 21 of the 24 concentrates; semi- or solid gel
formation occurred in 13 of these products. (R. L. Huggart, A. H. Rouse,
C. D. Atkins, F. W. Wenzel, R. W. Olsen, E. L. Moore, R. Patrick and R. Barron.)

Standardization of Processed Citrus Juices and Concentrates.- Further work
on sugar hydrate formations in frozen grapefruit concentrates and concentrates
for limeades showed that temperature variations (-80 to 50F.) increased the rate
of hydrate formation. Additional packs were prepared to determine effect of
heat treatment on this formation.

Grapefruit packs having various Brix/acid ratios were prepared for the Agri-
cultural IMarketing Service, U.S.D.A. for future consumer preference studies. The
consumer preference survey conducted in Indianapolis on canned orange juices,
which were processed at this Station during 1952-53 as previously reported, has
been completed by the U.S.D.A. and results will be published in the near future.

Because of the widespread interest in dietetic foods, investigations were
initiated to determine the possibilities of using Sucaryl, a non-caloric sweetening

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

agent, in the production of various citrus products such as orange and grapefruit
juices, frozen concentrate for limeade, canned and frozen grapefruit sections,
and frozen desserts such as tangerine sherbet.

With assistance from personnel of the U.S.D.A. Production and Marketing
Administration, Winter Haven, Florida, many samples of frozen orange concentrates
were collected twice each month throughout the processing season from 23 commer-
cial plants that were producing such products in Florida. Characteristics of all
of these samples have been or will be determined to provide information to the
citrus processors concerning the quality of this representative sample from the
1953-54 pack. Analyses will include acid, total soluble solids, peel oil, pectin
and glucoside content, pectinesterase activity, degree of clarification and
gelation after storage at different temperatures, flavor, color and microbiologi-
cal counts. (R. W. Olsen, E. L. Moore, R. L. Huggart, C. D. Atkins, A. H. Rouse,
E. C. Hill, F. W. Wenzel, R. Patrick and R. Barron.)

Relationship of Heat Treatment to the Quality of Processed Citrus Juices
and Concentrates'.- Work has been continued through the year on this project
although the grant-in-aid concerned expired in December 1953.

The use of heat is a practical means by which the processor can eliminate
enzymic and microbiological changes during processing and storage of citrus
juices and concentrates. By preventing these changes, the "cloud" or turbidity
is retained and the formation of gel is obviated by protecting the natural pectin
found in the extracted products from enzymic deesterification and microbiological
spoilage. Time-temperature relationships for heat inactivation of pectinesterase
in Villafranca lemon juice, pH 2.4 and 8 percent pulp by volume, were determined.
Temperature ranged from 1250F. to 1850F. at retention times of 0.8, 3, 6 and 12
seconds in a tubular pasteurizer. Complete inactivation was obtained at 1850F.
in 0.8 second, 1750F. in 3 seconds, and at 1650F. when heated to this tempera-
ture in either 6 or 12 seconds.

Complete inactivation of pectinesterase in Valencia orange juices, pH 4.1
and 8 percent pulp, at 1-, 2-, 3- and 4-folds with retention times of 3 seconds
occurred at 2100F., while holding times of 6 and 12 seconds required either
2050 or 2100F. With retention times of 3, 6 and 12 seconds, the enzyme in Pine-
apple orange juices, pH 3.9 and 8.5 percent pulp, of 1- through 4-folds was com-
pletely inactivated at 2100, 2050 and 200F., respectively. Seedy grapefruit
juices, pH 3.3 and 6.5 percent pulp, heated in 3, 6 and 12 seconds to 2050, 2000
and 1950F. respectively showed complete inactivation of pectinesterase regardless
of the fold. The percentage inactivation of pectinesterase in citrus juices
and concentrates increased when either the temperature of heat treatment or the
retention time in the pasteurizer was increased.

Analyses have been completed on packs of 420Brix concentrates which were
prepared, as reported in the 1953 Annual Report, from Parson Brown, Pineapple
and Valencia orange juices and Dancy tangerine juice in which juices to the
evaporator were heated in 6 seconds and cooled in 14 seconds so that approxi-
mately 0, 50, 90 and 100 percent of the pectinesterase was inactivated. The

1American Can Company cooperating through the establishment of a grant-in-aid.
Florida Citrus Experiment Station and
Florida Citrus Commission, Lake Alfred, Fla.


pulpy cut-back juices were not heated. Except for Dancy tangerine concentrate,
the three orange juices when concentrated to 550Brix lost water-soluble pectin
while the polyphosphate-soluble pectin increased in the unheated juices. The
pectic substances in the juices heated prior to concentration remained constant
during the processing period. No hydrolysis of protopectin was found during
the processing of the four varieties of juices. Loss of activity during con-
centration of the unheated juices to 550Brix varied from 6.8 to 22.8 percent.
Unheated samples of 42~,rix concentrates when placed at 80*F. for 24 hours
showed a further loss of water-soluble pectin and a further increase of the
polyphosphate-soluble pectin, while the heated samples remained fairly constant
in their pectic substances. The loss of pectinesterase activity during storage
ranged from 4.3 to 41.4 percent. Since there were no significant changes in
the pectic substances in most of the heated samples during storage, neither
clarification nor gelation occurred in these samples. However, the unheated
samples, except the tangerine, did show definite and extreme clarification after

Single-strength Valencia orange juices, pH 4.0, inoculated with Lactobacillus
plantarum and Leuconostoc mesenteroides and juice containing only the unidentified
cultures common to grove-run fruit and damaged drops were heat treated at
135, 1450, 165, 1750, 1850 and 1900F. for 0.8, 3, 6 and 12 seconds. L. plantarum
and L. mesenteroides were inactivated when the juice was heated at 1650F. for
6 seconds and at 165*F. for 3 seconds respectively. The unidentified organisms
in single-strength juices were not inactivated completely, but at 1650F. for
0.8, 3, 6 and 12 seconds, the numbers surviving were 225 or less per ml.

Hamlin and Pineapple orange juices, pH 3.7, both single-strength and 2-,
3- and 4-fold, containing the unidentified contamination of grove-run fruit
followed about tha same trend in the numbers of organisms surviving as previously
indicated. Single-strength juices in each instance would be as good as com-
mercially treated products. The concentrates from these varieties showed
870 to 40 organisms per ml. after heat treatment at 1650F. for 3 seconds for
Hamlins and %0 to 180 per ml. at 1650F. for 3 seconds for Pineapples. In 2-
fold Hamlin juice the number of organisms that survived ranged from 570 to 40
per ml. at 1650F. for 3 seconds and in 2-fold Pineapple juice 230 to 80 per ml,
survived at 1650F. for 3 seconds. In 4-fold Hamlin juice 500 to 50 per ml.
survived at 1650F. for 3 seconds and 290 to 4 per plate in Pineapple 4-fold
juice at 1650F. for 3 seconds. In concentrates the numbers surviving decreased
with the increase of concentration.

Examination of four Valencia orange juices, extracted by different methods,
showed significant variations in juice composition. Pectinesterase activity,
pectin and glucoside content, factors of importance to juice quality, were
greater in those juices containing the larger amounts of pulp or water-insoluble
solids. Revised procedures and techniques for the extraction of pectic sub-
stances have been devised. (A. H. Rouse, C. D. Atkins, R. Patrick, E. C. Hill,
R. L. Huggart and E. L. Moore,)

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


Storage Studies on Processed Citrus Juices and Concentrates.- The degree of
clarification and gelation in citrus concentrates subjected to above OOF. storage
temperatures may be lessened by partial inactivation of the pectinesterase by
heat treatment. To obtain processing and storage information on heat-treated
concentrates, 24 packs of 42OBrix Pineapple orange concentrates and Valencia
orange concentrates were heated prior to concentration or at different stages of
the concentration process. Samples of these packs were placed in short-term
storage at 800F. for 24 hours and in long-term storage at -8o, 100, 20, 320
and 400F. for several weeks or longer.

Pineapple orange juice, pH 3.8 and pulp content of 8 percent, was removed
from the evaporator at 2-, 3- and 4-folds. The 1-fold represented the single-
strength juice and was not sent to the evaporator. Each fold was divided into
three equal volumes representing a control (unheated), and juices heated to 1500
and 175OF. in 6 seconds and cooled in 14 seconds. The control juice (unheated)
was also passed through the tubular pasteurizer and cooling unit. The 12 juices
were concentrated to 550Brix, and cut back to 42oBrix with an unheated pulpy
juice containing 30 percent pulp by volume, and packaged. All concentrates were
then stored at -8*F. and later placed at the various storage temperatures.
Valencia orange juice, pH 3.9 and pulp content of 8 percent, was processed
similarly with the exception that the unheated pulpy cut-back juice contained
20 percent pulp by volume.

Heating the Pineapple orange juices to 1500F. resulted in 57 to 73 percent
inactivation of pectinesterase and heating to 175oF. inactivated 92 to 93 percent.
The finished concentrates, cut back with unheated pulpy juice, showed inacti-
vations of 35 to 53 percent and 52 to 61 percent, respectively.

The Valencia orange juices heated to 1500F. showed a 55 to 70 percent
inactivation of pectinesterase and 92 to 93 percent when heated to 1750F. The
finished concentrates, cut back with unheated pulpy juice, showed inactivations
of 33 to 49 percent and 60 to 68 percent, respectively.

An interesting trend was observed in both the Pineapple and Valencia
orange juices heated to 1500F. that showed a greater inactivation of pectin-
esterase at the 2- and 3-folds than at the 1- and 4-folds.

Storage studies are continuing on these products. (E. L. Moore, R. L. Huggart,
R. Patrick, R. W. Olsen, C. D. Atkins, A. H. Rouse, E. C. Hill and R. Barren.)

Microbiology of Frozen Concentrated Citrus Juicesl.- The diacetyl test,
suggested by this Station in 1952, as a rapid quantitative colorimetric method
for the detection in citrus juices of actylmethylcarbinol and diacetyl as an
indication of microbiological activity, has found increased application as a
bacteriological control procedure in citrus concentrate plants. Of the 23 con-
centrate plants operating this season, 15 used the diacetyl test to some extent.
Many of these plants used the test as the principal method of preventing the

IAmerican Can Gempany cooperating through the eatablishmet of a grant'in-add.

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


occurrence of spoilage during the evaporating process. Improvements in the test
have made it a rapid, simple and reliable control procedure. When the organisms
become established in the juice, the acetylmethylcarbinol and diacety production
increases at a more rapid rate than it is removed by evaporation. I-dications
are that the test is most advantageously run on juice samples taken f:om the
second or low Brix stage of the evaporators where variations in diacetyl content
are most conspicuous. Sampling points and evaluation of results may not be the
same for any two plants. Tests were run on 160 to 220Brix concentrate samples
from the second stage of a commercial evaporator, and the data illustrated the
characteristic increased production of diacetyl (and acetylrethylcaxbinol) and
the rapid progression to spoilage after 5 ppm diacetyl is reached in the distillate.

A method for the detection in citrus juices of keto compounds that are
products of deterioration has been applied to juices of kx.own quality including
the best; also to juices from fruit of not good quality but acceptable. This
method made it possible to select the juice according to quality. When the test
was applied to juices from industrial packs, a wide range of values were obtained.
Generally, concentrates from plants that operate with care and are mindful of
quality did not show inferior ratings. The pectin in the juice interfered with
the test, but it may be only accentuating the color formed from deterioration
products. A correlation may be noted between the color from deterioration,
intermediate products, and the pectin extracted from the peel of decomposing,
over-mature fruit.

Sorbic acid added to tangerine puree sherbet base in concentrations of
0.025, 0.05 and 0.1 percent by weight preserved the puree for 42 days at 80oF.
Puree with no sorbic acid fermented in six days at room temperature; similar
samples placed at 400F. did not ferment during the 42 days of observation.
Sorbic acid tends to be more bactericidal to slime and gum forming bacteria
than to yeast in that the former organisms die off first in puree containing
this acid. (R. Patrick, E. C. Hill, and F. W. Wenzel.)

Oxidizing Enzymes in Citrus Products.- Packs of Duncan grapefruit and of
Hamlin, Pineapple and Valencia orange concentrates were prepared to determine
various factors in the development of "castor-oil" or "cardboard" flavors in
citrus concentrates. This off-flavor developed in all of the products packed
when air was whipped into the concentrate by means of a Waring Blendor. Pre-
liminary results indicated that although off-flavor was not present in the con-
centrates when initially packed, it developed very rapidly even when the products
were stored at temperatures below OoF. Furthermore, when a crude peroxidase
extract was added to some of the concentrates the same off-flavor was obtained.
These results support the hypothesis that oxidation is a factor in the develop-
ment of the defect.

Further work is being carried on to determine the effect of various parts
of fruit and of air closure on the development of off-flavors. (R. W. Olsen,
E. L. lioore, F. W. Wenzel and R. L. Huggart.)

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


Color of Citrus Products.- Color differences in fresh and processed
citrus concentrates and juices were objectively measured with the Hunter Color
Difference Meter. However, neither this nor any other instrument now available
was found satisfactory for determining objectively the actual visual color of a
citrus juice as seen by an observer. Color variations in a large number of
samples of commercial citrus products, such as frozen orange concentrates,
canned single-strength juices, and blended juices, were measured using the Hunter
Color Difference Meter to provide data which after careful evaluation may be used
as the basis for future quality standards. (R. L. Huggart and F. W. Wenzel.)

Factors Affecting the Quality of Processed Grapefruit Products.- Results
of storage studies on samples of canned grapefruit sections obtained from a com-
mercial plant and stored at 320, 600, 700, 80 and 90OF. indicated slight
changes in flavor, color and firmness when stored at 700F. for one year. Marked
changes also were evident in the samples stored at 800F. or above after one year.
Analysis of the types of pectin in these products showed that hydrolysis of pro-
topectin occurred and progressed more rapidly at the higher temperatures of

Naringin, a bitter glucoside that occurs in grapefruit, often causes bitter-
ness in processed grapefruit products and excessive amounts are undesirable.
Preliminary work showed that the glucoside content of grapefruit juices increased
with extraction pressure. (R. L. Huggart, F. W. Wenzel, R. W. Olsen and E. L.

Production and Use of Activated Citrus Sludge.- The data collected on the
treatment of citrus wastes by the activated sludge process and reported last year
was rechecked and statistically analyzed. The following conclusions have been
drawn from the results of these investigations:

1. When properly executed, the activated sludge process offers an excellent
means of treating citrus wastes.

2. Inorganic nutrients need not be added to the raw waste.

3. The reduction in total and organic (volatile) solids is not a good indi-
cator of the efficiency of treatment of citrus waste. The Biological Oxygen De-
mand (B.O.D.) more nearly reflects changes taking place in the waste during

Equipment for the production of citrus sludge on a somewhat larger scale
was employed to investigate the use of dried citrus sludge as a vitamin supplement
in animal feeds. Forty gallons per day of diluted orange juice (0.25 percent
total solids) were pumped at a steady rate into a single 30 gallon aeration tank.
The sludge was settled from the overflow and recirculated. Excess sludge was
withdrawn daily and stored at 320F. until a sufficient quantity was obtained
when it was centrifuged and dried on a drum drier.

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

A minimum of analytical work was carried out during this run since the sole
object was to obtain a suitable quantity of sludge. However, the following ob-
servations were made:

1. Decreasing the amount of air caused a lowering of the aerator pH, poor
sludge settling and increased B.O.D. of the effluent. Returning the air rate to
the normal level reestablished the more favorable conditions.

2. The culture contained many protozoa. Large numbers of Vorticelli were
associated with a healthy sludge.

3. The addition of a soil suspension when the sludge appeared to be deteri-
orating restored good sludge condition.

4. During the latter part of the run, the pH gradually decreased for no
apparent reason. The addition of a small amount of alkali (58.8 ppm of NaOH)
corrected this situation before permanent harm was brought about in the culture.

By chick feeding trials 2.0 micrograms of vitamin B12 per gram of sludge
were found. By chemical and microbiological analyses the following were found:

Niacin 35.0 micrograms/g. Pyridoxin 5.0 micrograms/g.

Riboflavin 9.4 Pantothenic acid 20.0

Vitamin B12 1.5 Thiamin 5.0

The sludge was also found to contain 15.75 percent protein.

Based on the published vitamin analyses of other animal feed supplements,
dried citrus sludge should have a value between 50 to 7 1/20 per pound which
would be sufficient to pay for disposal of the sludge by drying and marketing.
Sale of this by-product thus offers a means of recovering part of the cost of
citrus waste disposal. (R. R. icNary, M. H. Dougherty and R. W. Wolford.)

Inositol in Citrus Fruits.- Preliminary investigations on the occurrence
of inositol in citrus fruits and its ultimate recovery as a by-product have con-
cerned: (1) methods for analysis of inositol in citrus fruits and juices, (2)
the preparation of samples for analysis, and (3) methods for the isolation, re-
covery and purification of inositol from citrus juices.

The microbiological assay method and a chemical method employing periodic
acid oxidation are the only existing methods. Only the chemical method has been
employed thus far in this laboratory. Since both of these methods are subject
to error in the presence of small amounts of sugar, a new method using filter
paper chromatography has been investigated and has proven quite successful as a
qualitative and semiquantitative method for the detection and estimation of
inositol in citrus juices. Experimental work is now in progress to establish the
technique in paper chromatography for the quantitative determination of inositol,
as well as other constituents of orange juice.

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


Various hydrolysis procedures have been studied to determine the conditions
necessary for quantitative separation of inositol from its compounds and other
interfering substances.

During these studies on inositol a small amount of crystalline inositol of
reasonably good purity was recently isolated from 55OBrix orange concentrate. As
far as known, the isolation of this substance from orange juice has been accom-
plished only once before by Nelson and Keenan (Science, 77, 1933) with a yield
amounting to only approximately one-fifth of that obtained in this laboratory.
(R. W. Wolford, R. R. McNary and M. H. Dougherty.)

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


Florida Citrus Oils.- For a good many years the manufacturers of citrus
oils have used tin dipped drums for storing and shipping their oil. This year
these drums were supplied by a manufacturer who extended his tin with lead;
consequently a considerable quantity of oil produced this past season has become
adulterated with lead. Work was done to determine the most economical method of
removing the lead from the oil without adversely affecting quality. Three methods
were developed, each having a specific advantage.

During this past year Bulletin 521, "Essential Oils from Florida Citrus,"
was published. This is a compilation of all previously published articles on
citrus oils resulting from research at this Station. (J. W. Kesterson and
R. Hendrickson.)

Refinement of Citrus Molasses.- In the continued effort to refine and
improve citrus molasses, numerous organic solvents and chemical agents were
tried in an attempt to extract or precipitate valuable new by-products that
would partially or wholly defray the expense of the operation. Particular atten-
tion was devoted to the possibility of recovering hesperidin and naringin which
are being investigated currently under State Projects 622 and 646. Of those
organic solvents used having the desirable characteristics of being both immiscible
in citrus molasses and yet showing some solubility for these glucosides, all were
found to gel molasses even at 50OBrix and therefore to be useless. Partially
successful were such solvents as isopropyl alcohol, acetone, tertiary butyl
alcohol and n-butyl alcohol. Among the chemical agents that showed promise were
various lead salts which precipitated voluminous quantities of insoluble substances,
including the glucosides, from citrus molasses. The non-selective nature of lead
salts in recovering glucosides may involve too great an expense to be practical.

With the more recent attention given to vitamin P extracts from citrus
molasses, an effort was made to find a chromatographic method of analysis for
vitamin P. Some difficulty has been encountered in finding a chromogenic spray
specific for the analysis. (R. Hendrickson and J. W. Kesterson.)

Recovery and Utilization of Naringin.- Studies this past year were designed
to assess the effect of many variables that would be important in the commercial
recovery of naringin. In this investigation Duncan grapefruit was processed
from September through April by a standardized procedure to evaluate the effect
of maturity on yield. In extracting naringin there was found to be an advantage
in recycling the mother-liquor at certain times of the year. Since naringin is
fairly soluble in water, extraction proceeded readily regardless of the size to
which grapefruit peel was cut prior to processing. The tendency of naringin
solutions to remain in a supersaturated state was a troublesome factor at times,
and although certain remedies were tried the trouble has not been eliminated.

Attention was also devoted to the possible development of new uses for
naringin and other glucosides. A process was devised for producing an anthocy-
anidin dye from naringenin for use in color-adding citrus fruit. Difficulty was
encountered in making stable solutions of proper tinctorial value. Similar dif-
ficulty was encountered with a new type azo naringenin dye. (J. W. Kesterson and
R. Hendrickson.)

Florida Citrus Experiment Station
Lake Alfred, Florida


Recovery and Utilization of Hesperidin.- Following the procedure previously
found to give the highest and most consistent yields of hesperidin from orange
peel, a survey was made to evaluate some of the other factors affecting yield
which would be of interest to the industry. Included among these factors studied
were fruit maturity, variety, size of peel, and reuse of the extraction mother-

Of the three orange varieties studied; Parson Brown, Pineapple and Valencia
representing early, midseason and late season fruit; the peel of Pineapple
oranges consistently gave the highest yield of hesperidin on a per ton of peel
basis. This same relationship held true whether the three varieties were pro-
cessed on the same day or at the time of equal maturity as determined by Brix/
acid ratio. The highest yield of hesperidin, 16.6 Ibs. of hesperidin per ton of
peel, was obtained in September by extracting Pineapple peel and recycling the
extraction mother-liquor. As the season progressed there was a noticeable de-
crease in yield and purity of the hesperidin obtained from each variety. Yields
were improved approximately 10 percent by recycling the extraction mother-liquor.
It was further shown that by finely chopping the peel, the yield of hesperidin
could be increased 20 percent in most cases.

Considerable attention has been devoted to the chromatographic analysis of
hesperidin containing solutions to corroborate results by the nonspecific Davis
method of analysis. The specific nature of chromatography has been helpful in
showing the positive absence or presence of hesperidin in other varieties of
citrus. In this study a new chromogenic agent was developed for analyzing
flavanones and amino acids. (R. Hendrickson and J. W. Kesterson).

Florida Citrus Experiment Station
Lake Alfred, Florida