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Summary of citrus processing and by-products research projects.
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6) 'WJ 1


SUMMARY OF CITRUS PROCESSING AND BY-PRODUCTS RESEARCH PROJECTS
Year Ending June 30, 1959

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


MICROBIOLOGY OF FROZEN CONCENTRATED CITRUS JUICES

State Project 550 R. Patrick and E. C. Hill


Commercial samples of frozen orange concentrate were again obtained during
the 1957-58 season and 193 samples were analyzed for streptococci and lactose-
fermenting bacteria. Streptococci were found in 145 samples of which 50 gave
the presumptive test and 22 of these the confirmatory test for enterococci. No
attempt was made to classify these streptococci in greater detail. Among the
lactose-fermenting bacteria encountered in these samples, 13 contained Aerobactge,
4 contained Escherichia, and 33 contained atypical forms of the non spore-forming,
lactose-fermenting group. It was evident from these analyses that heat treatment
was used in most of the processing plants during this season.

This project is being terminated with this report.


FLORIDA CITRUS OILS

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


This project was initiated to determine by what methods or procedures
essential oils of the highest quality could be produced in Florida. Such factors
as methods of processing and extraction, flavor, stability, fruit maturity, and
fruit variety have been under study.

A physiochemical procedure has been developed whereby coldpressed Florida
orange oil can be distinguished from coldpressed California orange oil. This
method has the further advantage of being able to show by what manufacturing
procedure Florida oils have been produced.

Citrus oils produced by the screw press, Pipkin roll, and FMC In-Line ex-
tractor were evaluated for quality during the 1958-59 season. The physiochemical
properties of these oils were considered normal.


STORAGE STUDIES ON CONCENTRATED CITRUS JUICES

State Project 611 E. L. Moore, A. H. Rouse, and C. D. Atkins

Packs of 420 Brix Valencia orange concentrates were prepared from both un-
cut and cut juices (Fla. Agr. Expt. Sta. Ann. Rept. 1958, p.210) to investigate
further the relative effect of heating either the single-strength juice prior
to evaporation of 2-, 3-, and 4-fold concentrates withdrawn during the evaporation
of unheated juice and subsequently heat treated.

Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
930 9/16/59 FWW








These 1958 Valencia orange concentrates were stored at -8, 10, 200, and
400F, and were examined at periodic intervals. After 1 year of storage, no
significant clarification occurred in the concentrates stored at -80 and 100F.
At 200 and 40OF, extreme clarification developed in all concentrates within 360
and 80 days, respectively. Retention of cloud was better in the concentrates
prepared from juices heated at the higher folds, and in all concentrates pre-
pared from uncut juices.

Ten packs of 420 Brix Pineapple and Valencia orange concentrates were pre-
pared in 1959 to investigate the effect of pulp washing techniques on quality of
concentrates after storage. Variations included the addition of unheated and
heated water extracts, both before and after centrifuging, to the evaporator
feed juice. Control packs were also prepared which did not contain any water
extract. The Pineapple and Valencia orange concentrates were withdrawn during
evaporation at 2- and 3-fold, respectively, and heated at 1750 and 1650F,
respectively. These products were then concentrated to 55 Brix, and cut back
to 420 Brix with unheated juice.

Varietal comparison on initial examination showed that the Pineapple orange
concentrates had higher values for pulp content, water-insoluble solids, water-
soluble and oxalate-soluble pectins, and total pectin. The Valencia orange
concentrates showed higher values for sodium hydroxide-soluble pectin. Values
that were not appreciably different for all of the products prepared from the
2 varieties of fruit were pectinesterase activity, flavonoids, relative vis-
cosity, and cloud. The results for cloud may indicate that less pulp or water-
insoluble solids are required in Valencia orange juice to produce a given amount
of cloud than that necessary for Pineapple orange juice.

In general, based on analyses to date, retention of cloud at 40OF is from
2 to 3 times longer in the Valencia orange packs than in the comparable Pine-
apple orange packs. This difference in storage life may be related to the
breakdown of the water-soluble to oxalate-soluble pectin during processing.


RECOVERY AND UTILIZATION OF NARINGIN

State Project 622 J. W. Kesterson and R. Hendrickson

There were no new developments on this project and it has been inactive
during the year.


RECOVERY AND UTILIZATION OF HESPERIDIN

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

The principal intent of this investigation during the past year has been
the refinement of the analytical methods for detecting hesperidin and naringin
in various extracts and the initiation of a small-fruit program to determined
the extent of improved recovery of citrus glucosides from small, immature fruit.


Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
930 a 9/16/59 FWW









More accurate analyses of hesperidin extracts were obtained with a newly
developed ultraviolet procedure that requires accurate pH control and addition
of minute quantities of copper sulphate with subsequent aeration to oxidize the
interfering ascorbic acid usually present. By this method samples of commercial
orange concentrate were shown to have only 20 to 30 per cent of the hesperidin
content shown by the more commonly used Davis test. The important conditions
were established for a somewhat similar ultraviolet method to analyze naringin
extracts. By this technique it was possible to analyze the effect of several
adverse processing factors upon grapefruit juice.

Extractions of small, immature Valencia oranges having an equatorial di-
ameter of 1 1/2-in, have resulted in yields of better than 50 lb. of pure
hesperidin per ton of fruit. At this size this yield is the equivalent of 50
lb. of pure hesperidin per acre of Valencia trees that are being studied. Maxi-
mum yields of hesperidin from small fruit were obtained under more alkaline
conditions than usually used and at dilutions that gave 0.6 per cent hesperidin
in the extracting liquor. Similar extractions of small grapefruit have been
equally impressive, with a refined procedure being found that is ideally suited
for a subsequent extraction of pectin from the same fruit.


CLARIFICATION AND GELATION IN CONCENTRATED CITRUS JUICES

State Project 649 C. D. Atkins, A. H. Rouse and E. L. Moore

Clarification and gelation, as well as some other characteristics related
to this problem were determined in 193 commercial samples of frozen orange con-
centrate which were processed during the 1957-58 season. Concentrates were used
to determine the degree of gelation, and reconstituted juices for the other
analyses.

Examination of the centrifuged reconstituted juices for initial "cloud"
showed no significant clarification in any of the samples. The 1957-58 samples
had more cloud than that in products examined during 1.956-57. An increase in
turbidity has occurred each year throughout the 4 seasons that these surveys
have been made. Of interest is the fact that the maximum cloud found in the
1953-54 samples was the same as the minimum cloud found in those from 1957-58.

The concentrates were examined for initial gelation, after thawing for 1/2
hour in running tap water, and 90.2 per cent showed no gelation, 5.2 per cent
very slight gelation and 4.6 per cent slight gelation.

Clarification and gelation were also determined after a storage or
"stability" test of 96 hours at 400F. Unsatisfactory definite or extreme clari-
fication occurred in 3.6 per cent of the 193 samples and 75.7, 11.9, and 11.9
per cent showed gelation corresponding to none, very slight, and slight,
respectively; only 1 sample or 0.5 per cent formed an undesirable semi-gel.

Pulp content in the 1957-58 juices ranged from 7.5 to 16.5 per cent by
volume and water-insoluble solids from 96 to 241 mg/100 g. The quantity of

Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
930 b 9/16/59 FWW









water-insoluble solids decreased from that in the 1956-57 samples and is indica-
tive of the use of lower pressures in juice extracting and finishing operations.
Pectinesterase activity, expressed on a soluble solids basis and multiplied by
1000 for easy interpretation, ranged from 0.2 to 9.8 units. The values were
considerably lower than those found in the previous year and would indicate that
the temperature and/or length of time for heat treatment of the juices had been
increased. Pectin in the centrifuged reconstituted juices, expressed as anhydro-
galacturonic acid, ranged from 25.0 to 55.0 mg/100 g. Flavonoids, expressed as
hesperidin, varied from 60 to 135 mg/100 ml.


CONVERSION OF CITRUS TERPENES TO USEFUL CHEMICAL COMPOUNDS

State Project 817 W. F. Newhall


Work has been continued on the synthesis of new chemical compounds from
d-limonene, the most abundant citrus terpene, with the object of furnishing more
profitable outlets for this by-product. A number of new compounds have been
prepared which have shown marked fungicidal properties in preliminary tests as
antimildew agents on fabric and as fungicides for the control of blue mold and
stem-end rot in fresh citrus fruits. Tetrahydrocarvone was not effective in
dilutions greater than 1:100 and, therefore, is not very promising as a fungicide
on fabrics. It did serve to mask the amine-like odor of some other compounds.
In dilutions of 1:1000, l-hydroxy-2-amino-p-menthane, with and without tetra-
hydrocarvone, did not give consistently effective results. However, 1-hydroxy-
2-dimethylamino-p-menthane gave good control of mold without tetrahydrocarvone
in dilutions of 1:1000 and also with tetrahydrocarvone in dilutions of 1:10000.
This result was comparable to that obtained with salicyl anilide in a dilution
of 1:10000. The latter compound is accepted by the U. S. Army as a fungicide,
None of the compounds possessed bactericidal properties. (Fungicide tests were
done in cooperation with Dr. Roger Patrick, Bacteriologist.)

The synthesis of these fungicidal derivatives has been accomplished in 3
steps. Partial hydrogenation of d-limonine without solvent, over a 5 per cent
platinum on charcoal catalyst gives A -p-menthene in virtually quantitative
yield, (Fla. Agr. Expt. Sta. Ann. Rept. 1958, p. 226.) This hydrogenation
product is converted to p-menthane-l,2-epoxide in 60 per cent yield by brief
treatment with aqueous peracetic acid at room temperature. By heating under
pressure with aqueous ammonia, the epoxide is converted to a mixture of trans-
2-amino-l-p-menthanols. The mixed trans isomers of 2-methylamine-l-p-menthanol,
2-dimethylamino-l-p-menthanol, and 2-piperidy-l-p-menthanol are prepared in a
similar manner by reaction of the epoxide with methylamine, dimethylamine, and
piperidine respectively. All of these aminoalcohols are high boiling, colorless,
slightly viscous liquids which are strong bases only slightly soluble in water.
That the direction of ring opening in p-menthane-1,2-epoxide does proceed to
give derivatives of 1-p-menthanol has been established by an independent synthesis
of one of the isomers of 2-amino-1-p-menthanol from trans-p-menthane-l,2-diol of
known conformation.



Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
930 c 9/16/59 FWW





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PRODUCTION OF GLYCEROL AND GLYCOLS FROM CITRUS FRUIT WASTES

State Project 921 Roger Patrick and S. K. Long


Preliminary studies on the production of 2,3-butylene glycol by fermentation
of citrus press water are in progress. In general, the citrus press water uti-
lized as substrate was more easily prepared for fermentation when collected from
the citrus feed mill after liming and heating. These treatments poised the pH
within the proper range for fermentation and improved storage quality. As ex-
pected from existing analyses, plain press water was found to be an inadequate
substrate for this fermentation; however, supplementation with urea and inorganic
phosphate, with added calcium carbonate to stabilize pH, permitted vigorous and
rapid fermentation.

The cultures employed included an established 2,3-butylene glycol producer,
Aerobacter aerogenes (NRRL B-199), and an unidentified bacterium recently iso-
lated from soil in the vicinity of a citrus feed mill. Fermentation studies
were carried out in 300-ml quantities of supplemented press water in 1-liter
flasks on a reciprocating shaker at 3000, and in larger quantities in a 2-liter
and a 14-liter fermentor in water baths at 3000C under aerobic conditions. Yields
of 2,3-butylene glycol from the shaker and small fermentor were determined by
colorimetric analysis of the fermentation beer. Although an insufficient number
of batches have been produced in the large fermentor to permit an evaluation of
yields, the results on smaller fermentations indicate good production of the
glycol, ranging from 75 to 98 per cent of theory.

Recovery of 2,3-butylene glycol as the formal from the fermentation beer
has been attempted and, while conversion to the formal appeared to be satisfactory,
some difficulty has been experienced in hydrolyzing this compound to 2,3-butylene
glycol.


OTHER PROCESSING AND BY-PRODUCTS RESEARCH

Pectin and Pectic Enzymic Studies of Citrus Fruits and Citrus Processed
Products. Pectins were isolated as alcohol-insoluble solids (AIS) from 2 packs
of frozen commercial orange concentrate, 1 having a high and the other a low
pectic content, and 1 pack of commercial frozen grapefruit concentrate; also,
from an experimental pack of frozen orange concentrate prepared from Pineapple
oranges which had been extremely damaged by cold weather. The quantity of
water-soluble pectin found in the 2 orange concentrates, the grapefruit concen-
trate and the experimental pack of orange concentrate was 210, 105, 158, and
350 mg/l00 g, respectively. In citrus juice the water-soluble pectin gives the
juice body or consistency and serves as a colloidal stabilizer for the insoluble
suspended particles.

The pectic substances from each AIS were divided into 3 fractions by
successive extractions with distilled water, ammonium oxalate and hydrochloric
acid; the pectic substances in these extracts were obtained by precipitation
with alcohol.

Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
930 d 9/16/59 FW





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The purity of the pectina, based on their anhydrogalacturonic acid content,
was generally low, varying from 19.0 to 31.5 per cent for the water-soluble,
17.5 to 37.0 per cent for the ammonium oxalate-soluble, and 33.0 to 41.0 per
cent for the hydrochloric acid-soluble. Methoxyl contents of the pectic fractions
varied for the water extracts from 5.5 to 10.2 per cent, for the oxalate extracts
from 3.1 to 8.9 per cent, and for the acid extracts from 8.9 to 10.8 per cent.
Jelly grades for the water-soluble pectins, indicative of molecular polymerization,
ranged from 89 to 107 with the exception that the commercial orange pack with low
pectic content had no grade. Generally, the ash constituents including calcium
and magnesium, which cause gelation by combining with pectinic acid in frozen
concentrates, and the ammonium hydroxide group (R203) in the water-soluble pec-
tins varied with their methoxyl content; high methoxyl content resulted in lower
ash than did the pectins with low methoxyl percentages. Alcohol precipitates of
the 4 water extracts contained approximately 25 per cent crude protein and 25 per
cent invert sugar as a higher carbohydrate.

The experimental Pineapple orange concentrate prepared from frozen fruit
contained not only the greatest quantity of water-soluble pectin, but also
approximately 2 1/2 times greater flavonoid and AIS contents than the commercial
orange and grapefruit concentrates prepared from unfrozen fruit. (A. H. Rouse,
C. D. Atkins, and E. L. Moore.)

Standardization of Processed Citrus Products. Various characteristics of
commercial samples of frozen orange concentrate processed during the 1957-58
season were determined so that such data, together with similar information ob-
tained during previous seasons, may possibly serve as a basis for future quality
standards. With the assistance of personnel of the Agricultural Marketing
Service, USDA, Winter Haven, Fla., a total of 193 samples were collected by
visiting 23 plants on a semi-monthly schedule from December to June, inclusively.

The color differences in these orange concentrates were measured with a
Hunter Color Difference Meter. Hunter "a" values ranged from 0.7 to 9.1; "b"
values, 28.4 to 35.2; and "Rd" values, 18.2 to 30.6.

Diacetyl values ranged from 0.2 to 2.9 ppm; the diacetyl value is the
diacetyl equivalent of diacetyl and/or acetylmethylcarbinol in 25 ml of dis-
tillate from 300 ml of reconstituted juice. Soluble solids in the frozen orange
concentrates ranged from 40.40 to 44.80 Brix; total acid, as citric, 2.46 to
3.58 per cent; Brix-to-acid ratio, 11.8 to 17.0; and ascorbic acid, 118 to
185 mg/l00 g, which corresponded to 35 to 55 mg/100 ml in the reconstituted juices.
Recoverable oil varied from 0.008 to 0.088 ml/100 g of concentrate, corresponding
to 0.002 to 0.026 per cent by volume in the reconstituted juices.

The apparent viscosities of 185 commercial samples of frozen orange con-
centrate ranged from 250 to 1780 op when determined at 300C using a Brookfield
viscometer. (R. L. Huggart, M. D. Maraulja, R. W. Barron, E. C. Hill, and
G. H. Ezell.)

The market testing (Fla. Agr. Expt. Sta. Ann. Rept. 1958, p. 240) of canned
grapefruit juice sweetened with Sucaryl was completed and the results presented on
May 13, 1959, to the Florida Citrus Commission by Robert E. Frye, Market Develop-
ment Branch, Agriculture Marketing Service, USDA, Washington, D. C. The results

Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
930 e 9/16/59 FWW





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were very favorable for this new product. The amount of Sucaryl required for
satisfactory sweetness was inversely proportional to the Brix-to-acid ratio of
the grapefruit juice and it was about 135 times sweeter than sucrose when used
in this product. (R. W. Olsen and R. W. Barron.)

Characteristics of Processed Citrus Products Made from Freeze-Damaged
Fruit. Problems concerning the use of freeze-damaged fruit for the production
of frozen orange concentrate were extensively investigated by the examination of
both juices and concentrates, packed experimentally and commercially, using fro-
zen oranges made available by the severe freezes which occurred during the 1957-58
citrus season.

The effect of the degree of freeze damage on the characteristics of fresh
Valencia orange juice was determined by the examination of 18 lots of oranges and
juices from them, using the same extraction procedure. Sixteen lots were picked
in the same commercial grove, at intervals from February 28 to May 16, from 3
groups of trees which had been defoliated about 10 per cent, 20 to 30 per cent,
and 75 to 95 per cent. Two lots of dropped fruit in fair condition were collected
on different dates from under trees with extreme defoliation. To determine the
amount of damage, each lot of fruit was sampled before extraction and 1/4- and
1/2-in. cuts made at the stem end of each fruit in the 18 samples; thus, the
percentage scoreable against #1 and #2 grades were ascertained. The degree of
freeze injury ranged from 5 to 96 per cent scoreable against #2 grade, the
largest amount of damage being found in dropped fruit collected on February 28.
Comparison of data from examination of juices from lots of fruit picked on the
same date indicated that as the extent of damage increased, there was a decrease
in juice yield, Brix value, total acid and ascorbic acid, and increases in Brix-
to-acid ratio, pH, flavonoids, pectinesterase activity, water-insoluble solids,
and microbiological counts; slight increases also were noted in serum pectin and
cloud. The smallest juice yield and pectinesterase activity were found in juice
from dropped fruit, which also contained the greatest amounts of pulp, water-
insoluble solids, serum pectin, and microorganisms. Although some juice
characteristics changed as the degree of damage increased, the differences were
not great enough in most instances so that such properties could be used as a
measure of the amount of freeze damage as is now done by visual inspection after
cutting the fruit. However, flavonoid content, color, and yield of juice have
some possibility of serving as an indication of seriously damaged fruit.

Nine experimental packs of frozen orange concentrate were processed to
determine the effect of the amount of freeze injury in fruit on the characteris-
tics of this product. Processing procedures were the same for all packs, except
that stabilization temperatures of 1950F and 1750F were used for mid- and late
season juices, respectively. Fruit was used in which the only variable was the
degree of damage and this was based on inspection after a 1/2-in. cut. One batch
of midseason and 1 batch of late season fruit were each separated into 2 lots by
flotation; also, 2 batches of midseason fruit having 15 and 81 per cent damage
were mixed in different proportions so that 5 lots, each having a different de-
gree of damage, were available for processing. Results from the examination of
the 9 frozen orange concentrates showed that as the amount of damage in the fruit
increased, the juice yield and total acid decreased and ascorbic acid was almost
always less; Brix-to-acid ratio, pH, flavonoids, apparent viscosity, pulp, water-
insoluble solids, and serum pectin usually increased. Pectinesterase activity

Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
930 f 9/16/59 FWW








was low, because of heat treatment, and stability of these concentrates was
satisfactory. Color of all products was poor, but all except 1 were graded
"fair" in flavor and considered to be acceptable. Since the degree of freeze
damage in oranges used to prepare these products ranged from 7 to 81 per cent,
it is evident that satisfactory frozen orange concentrate can be made from
seriously damaged fruit; however, such products will usually be of only fair
quality.

Characteristics were determined for 193 samples of commercial frozen orange
concentrate packed during the 1957-58 season, when large quantities of frozen
fruit were available for processing. Comparison was made of these data with
that from the examination of 212 samples packed during the 1956-57 season.
Differences found were caused not only from the utilization of freeze-damaged
oranges, but also by variations used in processing procedures so that an accept-
able product could be made from the damaged fruit.

Although most of the concentrates processed when large amounts of freeze-
damaged oranges were available, were acceptable in respect to flavor, neverthe-
less, flavorwise they were not as good as when it was not necessary to use fruit
damaged by cold weather. Factors responsible for this decrease in flavor quality
included (a) the blending of larger percentages of early and midseason bulk con-
centrate with Valencia orange concentrate, which also caused a decrease in color,
(b) an increase in tartness because of lower pH and Brix-to-acid ratios resulting
from more acid, and (c) the occurrence in a greater number of the samples of un-
desirable COF or oxidized flavors and astringency.

The stability of the 1957-58 products was greater as indicated by a decrease
in clarification and gelation after storage for 96 hours at 400F. Since the
water-soluble pectin in the samples from both seasons was about the same, the
improvement in stability resulted primarily from the decrease in the pectinester-
ase activity, which was caused by an increase in either the temperature and/or
the length of time for heat treatment during the processing of these concentrates.

Increases in flavonoids and diacetyl values resulted from the use of freeze-
damaged fruit and a slight decrease in the average amounts of ascorbic acid
occurred. The use of less pressure during extraction and finishing procedures
is indicated by the smaller amounts of pulp and water-insoluble solids, which
also caused a decrease in the average apparent viscosities.

These results indicate that the Florida citrus processing industry followed
recommendations, based on data previously reported (Fla. Agr. Expt. Sta. Ann.
Rept. 1957, p. 235, and 1958, pp. 203, 238, and 240) and made by personnel of the
Florida Citrus Experiment Station, Florida Department of Agriculture, and Florida
Citrus Commission soon after the freeze of December 12, 1957, that acceptable
frozen orange concentrate of fair flavor and good physical stability could be
made from freeze-damage fruit provided that less pressure during juice extraction
and finishing and also sufficient heat treatment of evaporator juice, necessary to
prevent clarification and gelation problems, would be used. Also confirmed by
these results was the previously reported information that the use of freeze-
damaged oranges would intensify problems, such as those related to stability and
flavor, usually encountered in the production of frozen orange concentrate.
(F. W. Wensel, A. H. Rouse, Roger Patrick, R. W. Olsen, M. D. Maraulja, E. L.
Moore, E. C. Hill, R. L. Huggart, G. H. Ezell, R. W. Barron, and C. D. Atkins.)
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
930 g 9/16/59 FWW





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Recovery of Fruit Solids from Orange Pulp. Characteristics of both
experimental and commercial samples of water extracts of orange pulp were deter-
mined so that their quality could be ascertained and a comparison of the proper-
ties of such aqueous extracts could be made with those of orange juice. The
effect of various extraction procedures on the percentage of soluble solids
recoverable from orange pulp was also investigated.

Eight experimental extracts were prepared, using pulp from both Pineapple
and Valencia orange juices. The pulp was mixed with water in a tank, the mixture
agitated for a period of time after which it was passed through a screw finisher
set loosely to remove the major portion of the extracted pulp. Successive ex-
tractions of some of the batches of pulp were made. Seven samples of extracts
were also obtained from 4 commercial plants where fruit solids were being re-
covered by washing pulp with water. Variations in some of the characteristics
of these experimental and commercial extracts were very great because of the many
variables involved in their preparation, such as variety of fruit, water-to-pulp
ratio, extraction times, and other processing procedures. Ranges of values for
some of the constituents in the commercial samples are shown in Table, together
with ranges found in reconstituted frozen concentrated orange juices.

Sugars varied in all of the extracts examined from 67 to 82 per cent of
total soluble solids as indicated by the Brix values. Pectinesterase activity
was very high in all samples, except those in which the enzymic activity had been
greatly reduced by heat treatment. The cloud in the serum from centrifuged ex-
tracts was better in samples which were either low in pectinesterase activity or
contained a large amount of water-soluble pectin; also, relative viscosities of
the serums were higher for the extracts which contained the larger amounts of
water-soluble pectin. More flavonoids and water-soluble pectin were obtained
from pulp and the pectinesterase activity was greatly reduced when hot water
extraction was used. Orange aroma and flavor was practically nil in the experi-
mental and commercial extracts and when some type of flavor or aroma was detect-
able, it was similar to that usually associated with the peel rather than the
juice of oranges. Astringency, bitterness, and a thick consistency were detectable
in some of the samples.

Table _. Comparison of Characteristics of Commercial Water Extracts of
Orange Pulp with Those of Orange Juice.

Characteristic Range in Range in
water extracts1 orange juices2
Acid as citric % 0.59-0.70 0.80-0.98
Brix/acid ratio 1.7-20 13-16
Ascorbic acid mg/100 ml 35-38 39-56
Flavonoids, as hesperidin mg/100 ml 98-234 70-90
Pulp % by volume 1.0-44.0 7-11
Water-insoluble solids mg/lOOg 23-419 100-199
Pectinesterase-(PE.u.)g soluble solids X 1000 0.1-80.3 1.3-6.9
Water-soluble pectin mg/100 g 38-170 35-49
1 Values calculated to 120 Brix basis for comparison purposes.
2Range of values in reconstituted juices from 70 per cent or more of 212 samples of
commercial frozen orange concentrate collected from Florida plants during the
1956-57 season.
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
930 h 9/16/59 FWW





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That soluble substances are very rapidly extracted from orange pulp was
shown when 2 parts of pulp and 1 part of water by weight were mixed together for
several time periods. When 5 seconds and 1, 5, and 10 minutes were used, the
soluble solids recovered corresponded to 6.2, 6.5, 6.7, and 7.00 Brix, respectively

An increase of 6.5 per cent in the yield of soluble solids was indicated by
data obtained in the pilot plant when a comparison was made between a double juice
finishing operation with a combination of single juice finishing and 3 successive
water extractions of the pulp, using a 1:1 water-to-pulp ratio by weight and a
mixing time of 1 minute; thus, the economic advantage of pulp washing is readily
evident.

Since a relatively small volume of water extract of orange pulp will be
mixed with a large volume of evaporator feed juice, on the basis of data avail-
able at this time it is evident that the use of fruit solids recovered from pulp,
using rapid sanitary extraction procedures, will not cause any major effect on
the initial quality of frozen orange concentrate. (R. W. Olsen, R. L. Huggart,
F. W. Wenzel, A. H. Rouse, C. D. Atkins, E. L. Moore, R. W. Barron, S. V. Ting,
and G. H. Ezell.)

A pilot plant unit for pulp washing was constructed and used. This unit
consists of pulp feeding equipment and a series of 4 Chisholm-Ryder Seprosieve
screw finishers equipped with 0.020-in. screens. Countercurrent flow is used
with pulp being fed into the first finisher and finally discharged from the
fourth finisher; water is added to the fourth finisher and the extracts are then
pumped, using rubber-impeller pumps, successively back into each of the other 3
finishers with the final extract being discharged from the first finisher. Each
finisher separates pulp from a water extract and an open impeller pump for mixing
pulp and extract and circulating the mixture precedes the second, third, and
fourth finishers. When orange juice from a Food Machinery In-Line extractor was
passed through a screw finisher and the discharged pulp fed to this pilot plant
unit, the Brix value of the orange pulp was reduced from 11.70 to 3.10 Brix,
using a 1:1 water-to-pulp ratio, and the extract increased from 1.60 to 7.20 Brix
in passing through the unit. The recovery of soluble solids from the pulp in-
creased from 51 to 81 per cent as the ratio of water-to-pulp was increased from
0.5 to 2.0. When either 2, 3, or 4 finishers were used during countercurrent
extraction of orange pulp with a 1:1 water-to-pulp ratio, the soluble solids
recovered were 62, 75, and 83 per cent, respectively. (R. L. Huggart, C. D.
Atkins, R. W. Olsen, and R. W. Barron.)

Factors Affecting the Flavor of Frozen Orange Concentrate. Evaluation by a
taste panel of the flavor of 193 commercial samples of frozen orange concentrate,
obtained during the 1957-58 season, resulted in 12, 81, and 7 per cent being
graded as good, fair, or poor, respectively. Off-flavors responsible for the
poor grades given to 11 of these concentrates were of the COF or oxidized type,
usually described as being similar to castor oil, cardboard, or tallow; a stale
flavor was evident in 2 concentrates, and the other 1 sample had a buttermilk-
type flavor. Perhaps a considerable number of the samples were graded "fair"
because of some oxidized flavor, but not enough to justify a grade of "poor";
these COF flavors were indicated by 3 or more panel members in grading 22 of the
193 samples.

Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
930 i 9/16/59 FWW





-11-


Flavor and color data on 840 samples of commercial frozen concentrated
orange juice, obtained from Florida plants during 4 citrus seasons, were compared
to see if a relationship existed between these 2 characteristics. Evaluation of
flavor of these products was based upon grades given by a taste panel and relative
color quality was determined by measuring the Hunter Color Difference Meter "a"
values. Both the flavor and color of the frozen orange concentrates processed
during the late season were better than that in the midseason samples. A corre-
lation coefficient of 0.360 indicated significance at the 1 per cent level between
the Hunter "a" values for the 840 orange concentrates and numerical flavor grades
for the corresponding reconstituted juices. Thus, if the total pack for a season
is considered, then color is an indication of flavor quality. (F. W. Wenzel,
R. L. Huggart, R. W. Barron, M. D. Maraulja, and R. W. Olsen.)

Volatile Flavor Components in Citrus Juices and Processed Citrus Products. -
The continued emphasis being placed on maintaining good flavor in Florida citrus
processed products has resulted in a basis research study of the volatile com-
ponents responsible for the natural flavor and occasional off-flavors in these
products. With the advent of a relatively new and highly sensitive method of
analysis, gas chromatography, a more exacting study toward chemical identifi-
cation of volatile flavor components is possible.

The extremely low concentration of many of the natural flavor components,
along with their labile properties, necessitates very careful handling to mini-
mize chemical change. These characteristics have brought about an intensive
study of procedures for concentrating the recovered volatile components.

The oil-soluble components, the more readily recoverable portion, may be
analyzed directly by gas chromatography. However, the large amount of d-limonene
in the oil-soluble fraction imposes restrictions on the separation, resolution,
and identification of the remaining small percentage of oxygenated components
including esters, ketones, higher alcohols, and aldehydes.

Studies of the water-soluble volatile components have been facilitated
through the use of virtually oil-free aqueous orange essence, which has been
obtained from an essence recovery unit located at a commercial citrus processing
plant. In the laboratory, the volatile components contained in the orange
essence samples were separated and recovered by continuous solvent extraction.
Through a subsequent concentration procedure, at room temperature, relatively
high concentrations of volatile components were obtained.

Through the use of gas chromatography, infrared techniques, and conventional
methods of chemical analysis, some similarity between 15 known chemicals and
individual volatile flavor components of orange juices and oils have been
observed. (R. W. Wolford.)
S amples of orange essence supplied through cooperation of E. J. Kelly and
Associates, Inc., and Libby, McNeill and Libby.


High-Density Citrus Concentrate. A pilot plant single-stage evaporator,
significantly different from existing units, was built, installed, and tested
for the production of high-density citrus concentrates. An important feature
is its double surface heater with 3/8 in. between the 2 stainless steel heating
surfaces which total 17.5 sq* ft. A single-tube preheater is adjacent to the
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida. 930 j 9/16/59 FWW








double-tube heater. To the bottom of the vertical heater is directly attached
the evaporator pan, which also serves as a vapor separator chamber. The pan
contains an agitator to keep the more viscous product discharged from the heater
and the pan contents evenly mixed; also, a baffle to cause bursting of occluded
vapor bubbles in the concentrate to prevent them from entering the suction to the
circulating pump. Heat of vaporization is supplied by circulating warm water
through the preheater and heater. Vapor removal is provided by a steam jet
booster. The pan, preheater, and heater temperatures may be varied from 600 to
150OF by increasing the temperature of the heating medium or by lowering the
vacuum in the unit. The vapor removal capacity varies from 50 to 150 Ib/hour.

A positive type pump, especially machined with wide clearances between its
moving parts, is adjusted to the desired speed to recirculate the viscous con-
centrate through the preheater, heater, and pan. As concentrate is pumped up-
ward in the preheater, vapor bubbles formed within the product speed upward and
expand into the heater distributing the concentrate on both surfaces. Vapor
formed from the concentrate flowing downward in the heater aids in propelling
the mass evenly along the heating surfaces. Recirculation is continued until
the desired degree of concentration is obtained. (C. D. Atkins.)

High-density concentrates of 5- and 6-fold were prepared from Hamlin,
Pineapple, and Valencia oranges to determine the effect of degree of concen-
tration on their flavor stability during storage. Four-fold or 420 Brix con-
centrates were also packed for comparison purposes. Results will not be
available until examination of these products during storage for 1 year is
completed. Preliminary studies were also made on the use of 2-, 3-, and 5-fold
orange oils and also orange essence in orange concentrate to determine their
effect on flavor and flavor stability during storage. (F. W. Wenzel, R. W.
Olsen, and M. D. Maraulja.)

Rapid Method for Predicting the Stability of Commercial Frozen Orange
Concentrate. When gelation and clarification occur in frozen orange concentrate
during distribution and storage, the quality of the product is lowered and it
becomes less acceptable to consumers. Present tests to determine the stability
of this product usually necessitate storage at 400F for 96 hours or longer after
it is canned and frozen. The purpose of this investigation was to develop a
rapid method for predicting the stability of frozen orange concentrate during
continuous production in commercial plants and prior to the filling of the pro-
duct into cans for freezing.

The following rapid method was developed and applied to commercial samples
of frozen orange concentrate collected during the 1958-59 citrus season. Frozen
orange concentrate is thawed and 50 ml reconstituted with 3 volumes of deionized
water. Then the pH of 150 ml of juice is adjusted as rapidly as possible to
exactly 7.5 by adding 4N NaOH while the juice is rapidly stirred, the pH checked
with a pH meter, and the temperature maintained at 800F + 10F. As soon as the
pH reaches 7.5, a stopwatch is started and the mixture constantly stirred, but
without further adjustment of pH. After exactly 10 minutes, 50 ml of the re-
acted mixture is pipetted immediately into a beaker containing 2.7 ml of glacial
acetic acid to stop the enzymic reaction. The mixture is centrifuged and the
cloud or turbidity of the supernatant liquid determined by colorimetric measure-
ment of light transmittance.

Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
930 k 9/16/59 FWW





-13-


For comparison purposes, the stability of 197 commercial samples of frozen
orange concentrate was determined by the rapid method and also after storage for
96 hours at 400F. The same degree of clarification was indicated by both pro-
cedures in 87 per cent or 171 samples, but poor correlation was found for 26 or
13 per cent of the samples. However, some gelation occurred in 25 of these 26
samples, thus providing a reason why 100 per cent correlation was not obtained
between the two methods. These data indicate that the possibilities are very
good for the development of a rapid method for predicting the stability of fro-
zen orange concentrate. (Kuang C. Li, George H. Ezell, and R. W. Olsen.)

Citrus Vinegar. Excellent vinegars from orange, grapefruit, and tangerine
juices were produced in a submerged fermentation type of equipment patterned
after the latest commercial practice. Also, a vinegar with an entirely different
aroma and flavor was made from press liquor from citrus feed mill operations.
This is the material that ordinarily is made into citrus molasses. Special
treatment to eliminate peel oil had to be given this raw material before it could
be used. Over 100-gal. quantities of all 4 vinegars were produced so that ade-
quate samples might be available to interested parties.

In the operation of the submerged fermentation type of vinegar generator,
close attention was paid to the feed rate, aeration rate, and temperature.
Approximately 86OF was found to be the optimum temperature. Above this level
the bacteria were very sensitive to the ethanol concentration, thus making the
fermentation difficult to control. In addition, the aeration rate needed to be
adjusted to the activity of the acetic acid bacteria. Excess aeration inhibited
bacterial action and insufficient aeration deprived the bacteria of the necessary
amount of oxygen. The rate of feeding was also adjusted to the activity of the
bacteria. Insufficient feeding allowed the bacteria to oxidize some of the
acetic acid already produced because of lack of adequate alcohol. Overfeeding
caused accumulation of alcohol which eventually depressed the activity. It was
frequently difficult to diagnose the actual condition of the fermentation and
determine the change necessary to bring about optimum conditions because of the
overlapping of these effects. (R. R. McNary and Marshall H. Dougherty.)

Inositol in Citrus Fruits. The objective of this investigation has been
the development of a satisfactory economical method for the extraction of myo-
inositol from citrus peel, juices, and processing or by-product liquids.

Among 12 general processes studied, chemical precipitation procedures have
proven to be quite satisfactory for the isolation of inositol. However, calcu-
lations based on laboratory experiments indicate the reagent costs to be con-
siderably in excess of the maximum return expected on the product.

A serious difficulty in the recovery of inositol from citrus liquors has
been the large amounts of sugar present. This difficulty could be overcome by
employing strong acid hydrolysis for the destruction of the sugars. However,
this does not appear advisable considering the relatively small amount of
inositol present as compared to the high concentration of sugars and their
potential value.

The use of waste liquors, such as citrus distillery slops, where the sugars
have been utilized for producing alcohol would be quite logical. The application

Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
930 1 9/16/59 FWW





-14-


of alcohol precipitation procedures for the isolation and recovery of inositol
from distillery slops has shown some possibility and would probably be more
economical. Another method employing citrus press liquor has, more recently,
been concerned with the selective removal of sugars, polysaccharides, and other
sugar-like substances from substrates used for inositol recovery. Fermentation
by Bacillus macerans, Escherichia coli or robacter aerogenes, as a preliminary
treatment, resulted in complete removal of the mono- and di-saccharides.
(R. W. Wolford.)

Production and Use of Activated Citrus Sludge. A study was initiated to
identify the amino acids in the protein contained in activated citrus sludge.
The amino acid analyses were made using paper chromatography.

Results indicate that there are between 15 and 20 amino acids in activated
citrus sludge and of these 8 have been definitely identified as aspartic acid,
glutamic acid, serine, glycine, threonine, alanine, leucine, and isoleucine.
(M. H. Dougherty.)

































Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
930 m 9/16/59 FWW




Season i~,eages of internal quality of Navel oranges from each grove, on 5 root-
stocks, and 4 aisze during 3 years. F.C.C.


1956-57 Season
Size 200 Size 150 Size 96 Size 70
Grove Brix Acid Ra uie Br id Rato Br, d Ratio Juice Brix Acid Ratio Juice Brix Acid Ratio Juice
% % ml* % aml* X % l* Z m l*


A37
A40
B33
C71
C72
C74
C77
C78
C79
C80
C82
C83
C85
C87
C89
C90
C91
D48
D51
D55
D58
D59


A41
A43
A45
A46
B30
C76
C84


9.64
11.04
10.37
11.70
9.98
11.46
10.86
10.77
10.74
11.89
10.95
9.53
10.87
12.56
10.19
10.62
12.80
9.90
9.45
8.00

9.80


9.30
11.21
9o21
9.01
10.56
9.87
12.35


.95
.89
.81
.80
.78
.85
088
1,06
.85
.95
.67
1.16
.88
.91
.79
.89
.79
1.12
1.25
1.00

1.07


.80
.80
.98
.90
1.25
.94
.83


10.5
12.8
13.6
15.8
13.3
14.0
12.8
10.6
13.2
14.0
17.6
8.3
12.6
14.3
13.4
13.1
16.8
8.8
7.7
8.3

9.4


11.8
14.9
9.7
10.3
.8.9
10.9
15.7


C88 11.46 .85 13.8


932
1105
1059
1029
1031
1117
1092
1171
1045
971
1251
1103
1138
1059
1091
1075
1054
984
1025
1092

1174


1137
1086
1139
1108
1087
1190-
1081


1023


9.63
11.45
10.45
11.61
10.13
11.82
10.93
10.75
10.84
11.77
10.86
9.50
11.96
12.35
9.84
10.93
12.91
10.10
9.52
9.14
9.50
10.16


10.60
10.91
9.33
9.87
10.03
11.07
12.52


.93
.86
.76
.77
.74
.78
.79
1.07
.84
.85
.63
1.06
.74
.88
.72
.79
.78
1.04
.97
.81
.94
.86


.68
.75
.89
,71
1.18
.78
.74


10.7
13.8
14.3
16.1
14.2
15.6
14.7
10.5
13.4
14.8
18.0
9.2
17.1
15.0
14.1
14.8
17.6
10.0
10.3
11.7
11,5
12.4


16.1
15.2
10.9
14.9
8.9
14.7
17.9


Sour o0
1335
1500
1547
1378
1385
1365
1429
1506
1339
1371
1552
1550
1506
1 167
1405
1377
1436
1320
1459
1404
1495
1576

Rough
1535
1353
1546
1528
1441
1677
1403


range rootstock


9.26
10.92
10.05
11.31
9.65
11.26
10.78
10,33
10.43
11.56
10.34
9.37
11.63
11.79
9.66
10.26
12.61
10.16
9.50
8.91
10.06
10.86


.94
.81
.73
.71
.68
.77
.73
.97
.84
.84
.61
1.01
.73
.83
.70
.73
.81
.74
.86
.77
.68
.70


lemon rootstock


10.05
10.49
8.43
9.86
9.91
11.02
12.18


.65
.69
.91
.67
1.03
.71
.71


10.2
14.1
14.4
16.6
14.9
15.3
15.6
11.1
12.8
14.9
18.3
9.5
16.6
14.9
14.4
15.0
16.8
14.3
11.5
12.2
15.9
16.7


16.1
15.9
9.4
15.5
10.1
16.1
18.1


Rusk citrange rootstock
11.59 .75 16.0 1388 11.45 .74 16.4


2144
2264
2271
2072
2021
2183
1882
2177
2213
2017
2349
2243
2111
2182
2201
2043
1936
1946
2210
2118
2053
2122


2203
2007
2390
2163
2166
2047
2020


2272


9.94
10. 15
9.53
10.36
10.13
11.00
10-65
11.18
9.40
9.45
11.38

8.94
9.80

10.30


10.16
10.70


8020
10.03


10.45

10.47


.56
.74
.62
.78
.70
.58
.72
.70
.67
.92
.71

.61
.64

.60


.56
.56


.68
.62


.92

.74


18.3
13.7
15.8
14.0
15.1
19.0
14.8
16.6
14.0
10.4
16.7

15.5
16.4

17.2


18.7
19.6


12.0
16.4


11.4

14.2


2967
3120
3045
3580
3213
3340
3432
2929
3600
3280
3380

3097
3048

2830


2651
2635


3060
3004


2599

3289


12.35 .51 24.2 3080


Juice in ml per 12 fruit.


I- II.----_LI __.__ II_ I--^







1955-56 Season
Size 200 Size 150 Size 96 Size 70
Grove Brix Acid Ratio Juice Brix Acid Ratio Juiee Brix Acid Ratio Juie- Brix Acid Ratio Juice
X% ml* % % l* % mi* % ml*


10.08; .79
10.39 .67
9.30 .87
9.88 .83
10.79 .74
9.25 .75
10.04 .80
9.18 .63
10.05 .69
10.79 .69


10.08 .67
10.61 .88
9.13 .79
9.77 .66
10.68 1.05


Sour orange rootstock
13.3 1483 9.71
15.9 1443 10.37
11.2 1453 8.97
12.4 1561 10.57
15.1 1434 10.40
12.6 1590 10.46
12.9 1498 10.34
15.1 1638 8.98
15.1 1505 10.26
16.1 1599 10.46

Rough lewmn rootstock


A37
A40
A42
A44
B33
D48
D51
D55
D58
D59


A41
A43
A45
A46
B30


9.86
10.53
9.35
9.39
10.78
9.00
9.45
9.10

9.95


8.10
10.79
9.54
9.46
11.11


.84
.72
.86
1.00
.71
.86
.65
.77

.52


.94
.93
.80
.77
1.09


B32 11.25 .74 15.7 984


Cleopatra too1tstock
11.16 .71 16.2 1424 10.72


.68 16.5 2071


10.75 .54 19.5 2931


1954"55 Season
Sonr arn e otnatocknicrk


Size 200
Brix.% Acid % Ratio


Size 150
Brix % Acid % Ratio
10.08 .83 12.4
10.83 .79 13.9
11.10 .71 15.8
10.26 .69 15.3
10.74 .70 15.9
9.53 .67 14.6
Rough lemon rootstock
9.90 .57. 18.3
9.59 .96 10.1
Cleopatra rootstock
10.43 .77 13.7


* Inue In ml nor 12 flif-


12.4
15.2
11.0
9.4
18.5
10.5
14.6
12.2

19.1


8.8
1%.1
12.1
12.6
10.4


1096
1107
1098
1160
1104
1246
1210
1008

1257


1080
1195
1244
1152
1284


9.72
10.63
8,28
9o11
10.03


15.7
12.2
11.6
15.3
10.4


1557
1586
1627
1504
1697


13.2
15.6
12.6
16.0
15.9
18.8
14.2
15.8
17.6
16.6


16.4
13.4
13.7
16.7
11.3


9.55


10.39
9.93
9.64
9.93

9085



8.87
10.35


2243
2085
2164
2251
2198
2108
2222
2224
2173
2285


2227
2379
2378
2153
2329


,65
0- 0
.56
.72
.59
.64

.57



.60
.76
t=>C
0 C


14.8


18.6
14.0
17.5
15.8

17.5



14.9
13.5
: C:,3


3195


3264
2477
3224
3091

3050



3410
3190


Grove
A37
A40
C71
D48
D51
D55


10.18
10.05
11.40
9.26
10.50
9.76

10.12
9.92

10.69


A41
B30


12.0
11.7
15.5
10.9
13.9
12.6

17.7
10.3

14.3


Brix %
9.78
10.90
10.83
10.28
10.73
8.87

9.45
9.06


Size 96
Acid %
.79
.70
.69
.63
.71
.61

.54
.89

.76


Ratio
12.7
16.0
16.0
17.0
15.7
14.8

18.1
10.3

13.3


9.83


- I- ~~-------- ---- ----- ---