Title: Effect of the use of freeze-damaged fruit on the characteristics of frozen concentrated orange juices
CITATION THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00080903/00001
 Material Information
Title: Effect of the use of freeze-damaged fruit on the characteristics of frozen concentrated orange juices
Series Title: Effect of the use of freeze-damaged fruit on the characteristics of frozen concentrated orange juices
Physical Description: Book
Creator: Westbrook, George Franklin,
Publisher: Florida Citrus Experiment Station and Florida Citrus Commission
 Record Information
Bibliographic ID: UF00080903
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 173258245

Full Text




Effect of the Use of Freeze-Damaged Fruit on the Characteristics of Frozen
Concentrated Orange Juices 1
George F. Westbrook, Jr.


The production of frozen concentrated citrus juices in Florida now dominates
the economy of the citrus industry, as the result of the meteoric rise in pro-
duction since its inception about ten years ago. Although the concentrate
industry has encountered some problems during these past few years, Mother Nature
has blessed this state with generally good weather and no serious freeze has
occurred since 1947 to pose other problems. Unfortunately, this period of balmy
weather cannot continue forever, for the history of freezes in Florida clearly
indicates that every day which passes brings just one day closer another major
freeze.

This research was undertaken to determine the effect of the use of freeze-
damaged fruit on the characteristics of frozen concentrated orange juice. It
was hoped that the results might indicate to processors the problems that would
occur if freeze-damaged fruit is used for the production of frozen orange con-
centrate, and thereby help them to avoid financial losses because of either
production difficulties or the preparation of concentrate of poor quality when-
ever severe freezes may occur in Florida in the future.


SUMMARY

To determine the effect of the use of freeze-damaged fruit on the character-
istics of frozen concentrated orange juice, a total of 37 experimental packs
was prepared. These included both midseason and late oranges, various degrees
of freeze injury, and heat treatment with other processing variables.

Recoverable oil, ascorbic acid, and pectinesterase activity were found to
be of little or no practical importance as distinguishing characteristics of
frozen orange concentrate prepared from freeze-damaged oranges, since very little
variation was found in these properties.

A reduction in total acidity, and resulting increase in Brix-acid ratio,
were characteristic in the packs made from freeze-damaged fruit, and usually
varied directly with extent of freeze injury.

The pH of the concentrates increased as extent of injury to the fruit
increased and approached danger limits for growth of microorganisms that can
cause spoilage of the juice in evaporators during processing.

The pulp content of the reconstituted juices in the packs processed simi-
larly usually increased with extent of freeze injury in the oranges.

1 Excerpts from doctoral dissertation "Effect of the Use of Freeze-Damaged
Fruit on the Characteristics of Frozen Concentrated Orange Juices" by
George F. Westbrook, Jr. University of Florida, June, 1957. 98pp., 23 tables,
and 8 figures.
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
813 9/26/57 FWW





-2-


Flavonoid content varied directly with extent of freeze injury and reached
large amounts in the products processed from damaged Pineapple-type oranges.
Deposits of hesperidin in evaporators, which lead to inefficiency during evap-
oration and possibly to a product of lower grade, may be a serious factor in
producing concentrate from freeze-damaged oranges.

A very high relative viscosity was found to be characteristic of concen-
trates prepared from freeze-damaged Pineapple-type oranges, but a low relative
viscosity was found in all of the Valencia orange concentrates regardless of
the amount of freeze injury. Therefore, this characteristic is of extreme
practical importance when processing midseason fruit, for as degree of concen-
tration increases, efficiency of operations decreases and may be reduced to the
point that the concentrate will have to be pumped from the evaporators at a
lower Brix than is desirable.

Increase in total pectin was characteristic of concentrate prepared from
freeze-damaged fruit. Abuse tests showed a shift from the water-soluble pectins
which maintain a good "cloud" to oxalate-soluble pectins that affect gelation and
clarification. The importance of differences in pectic substances due to freeze
injury cannot be evaluated in some instances at this time.

Gelation and clarification were almost always worse in freeze-damaged fruit
packs processed from Pineapple-type oranges, and varied directly with extent of
injury. Higher temperatures than 1750F. were necessary to prevent gelation and
clarification, but heat treatment of the cut-back juice was not found necessary
for that purpose when the evaporator-feed juice was heated at 1950F. Concentrate
prepared from freeze-damaged midseason oranges may be expected to be much more
subject to stability problems than that prepared from unfrozen fruit. Late or
Valencia-type orange concentrate from freeze-damaged fruit did not show this
characteristic.

Loss of flavor and/or development of off-flavors may occur rapidly in con-
centrate prepared from freeze-dam ged fruit, and this may add greatly to quality
problems. Heat treatment, necessary for stabilization, affected adversely the
flavor of concentrates made from freeze-damaged oranges.

The overall effect of the use of freeze-damaged fruit on the characteristics
of frozen concentrated orange juices was a reduction in quality, varying directly
with the extent of the freeze injury. The efficiency of processing operations
may be reduced, spoilage problems may become acute, and the operational season
may be shortened as the net result of yield losses, high Brix-to-acid ratios,
poor quality, and other factors.








Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
813a 9/26/57 FWW






-3-


LITERATURE CITED


Alderman, D. C. 1953. A survey of freeze damage to citrus trees in lower
Rio Grande Valley and its effect upon fruit quality. Proc. Seventh Ann. Rio
Grande Valley Hort. Inst., pp. 35-38.

Bartholomew, E. T., W. B. Sinclair, and R. P. Horspool. 1950. Freeze
injury and subsequent changes in Valencia oranges and grapefruit. Calif. Agri.
Exp. Sta. Bul. 719.

Beacham, L. M. 1941. Studies of Florida and California oranges in regard
to the relationship of frost damage to juice content. J. Assoc. Off. Agr.
Chem. 24: 788-793.

Burdick, E. M. 1951. Symptoms of freeze damage in citrus fruit. Proc.
Fifth Ann. Rio Grande Valley Hort. Inst., pp. 117-120.

Chace, E. M. and C. G. Church. 1927. Methods of detecting and measuring
frost injury. Proc. Fla. State Hort. Soc. 40: 112-116.


Davis, W. B. 1935.
oranges. Am. J. Bot. 22:


Detection and measurement of freeze injury in Valencia
559-566.


Florida Citrus Code. 1954. State of Florida citrus fruit laws. Florida
Citrus Commission and Florida Department of Agriculture.

Gary, W. Y. 1935. The effect of freezing on oranges. Fla. Dept. Agri.
Chem. Div., pp. 17-30.


Webber, H. J., E. E. Thomas, H. D. Young, and C. 0. Smith.
the effects of freezes on citrus in California. II. Changes
frozen oranges and lemons. Univ. Calif. Agr. Exp. Sta. Bul.


1919. A study
that take place
304.


Wenzel, F. W., E. L. Moore, A. H. Rouse, and C. D. Atkins. 1951. Gelation
and clarification in concentrated citrus juices. I. Introduction and present
status. Food Technol. 5: 454-457.

Young, H. D. 1915. The composition of frozen oranges and lemons. J. Ind.
Eng. Chem. 7: 1038-1041.









Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
813b 9/26/57 FWW




University of Florida Home Page
© 2004 - 2010 University of Florida George A. Smathers Libraries.
All rights reserved.

Acceptable Use, Copyright, and Disclaimer Statement
Last updated October 10, 2010 - - mvs