Group Title: Citrus Station mimeo report - Florida Citrus Experiment Station ; 56-7
Title: Changes in quality of canned grapefruit sections during storage
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 Material Information
Title: Changes in quality of canned grapefruit sections during storage
Series Title: Citrus Station mimeo report
Physical Description: 4 leaves : ; 28 cm.
Language: English
Creator: Huggart, R. L
Citrus Experiment Station (Lake Alfred, Fla.)
Florida Citrus Commission
Publisher: Florida Citrus Experiment Station :
Florida Citrus Commission
Place of Publication: Lake Alfred FL
Publication Date: 1955
 Subjects
Subject: Canned grapefruit juice -- Quality -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
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Statement of Responsibility: R.L. Huggart ... et al..
General Note: Caption title.
General Note: "October 4, 1955."
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Bibliographic ID: UF00072376
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 74711411

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Citrus Station Mimeo Report 56-7
October 4, 1955


Changes in Quality of Canned Grapefruit Sections during Storage
R. L. Huggart, F. W. Wenzel, E. L. Moore and R. W. Barren


The investigations reported here were undertaken to determine (a) the sta-
bility of canned grapefruit sections to color, flavor and firmness changes at
various storage temperatures, (b) changes in pectic substances in this product
during storage, and (c) the effect of the date of packing on changes in quality
of canned grapefruit sections during storage.


Part 1 Effect of Storage Temperature 1

Collection, storage and methods of examination. The samples of canned
sections used were taken over a 5-day period in January 1953 during commercial
canning operation at the plant in Tampa, Florida, of the California Packing Corp-
oration. Two cases (48 cans 303 x 406) of sections were obtained from the plant
each day for 5 consecutive days to obtain a representative sample. They were
allowed to firm up in the warehouse for 14 days until transferred to 320F. stor-
age in the laboratory. Equal numbers of cans of sections from each day's pack
were placed at 320 (control), 600, 70, 800 and 900F. storage on March 1, in such
a manner that a 5-can sample, consisting of one can from each of the 5 days, could
be removed from storage at a given temperature at scheduled examination dates.

A given 5-can sample of sections was opened and placed in a white enameled
tray. A panel of 4 people used organoleptic methods to score a sample against a
control sample that was stored at 320F. Samples or sections were rated for fla-
vor, color, and firmness. The changes found in the sections were listed as none
or 1, slight or 2, marked or 3, and extreme or 4. A portion of the syrup was re-
moved for determination of total acidity, total soluble solids, and pH. Twenty-
five of the best sections were removed from the sample and drained on a 6-mesh
screen. These sections were comminuted 3 min. in a Waring blender to furnish a
slurry for determination of pectin as anhydrogalacturonic acid (AGA), pectines-
terase activity, and color differences. Color differences were determined with a
Hunter Color Difference Meter.

Changes in flavor, color and firmness. At the beginning of the storage
period, single cans from each of the 5 packs were opened and compared. These
samples were found to be equal in firmness and color, although one can was found
to be rather tart. Some of the small segments were noted as being firmer and
more tart than large segments in the same sample. In all cans examined during
this investigation, the total acidity (citric) varied from 1.01 to 1.35%. The
total soluble solids varied from 17.00 to 19.90Brix with Brix/acid ratios varying
from 14.8 to 16.8. The pH ranged from 3.3 to 3.4.

Condensation of publication, "Effect of storage temperature on quality of
canned grapefruit sections", by R. L. Huggart, F. W. Wenzel and E. L. Mo p RIZ
Food Technology 2, 268-270 (1955). Reprints are available on request.,~2/

Florida Citrus Experiment Station
and Florida Citrus Commission, p Co 1C
Lake Alfred, Florida.
636 9/26/55-RLH






-2-


Flavor changes at 3-month intervals at the various storage temperatures are
shown in Table 1. The segments stored at 900F. were markedly different in 3
months and extremely different in 9 months from the control sample. Hydrogen
swells developed in the 900F. samples after 1 year. The 800F. segments showed
marked changes in 9 months, while the samples stored at 700F. showed only slight
changes in 1 year. Samples stored at 600F. showed little, if any, change in 1
year.

Color changes occurring in the segments are also shown in Table 1. The first
browning occurred in the sample stored 3 months at 900F. The darker color was
apparent in the sections and also in the drained syrup. Slight browning occurred
in the 800F. sample in 3 months and was also found in the 700F. sample after 1
year. Examination of the sections with the Hunter Color Difference Meter showed
a color difference in the samples stored at 800 and 900F. for 6 months. At 12
months, the color meter placed the 600F. sample with the control, but indicated
that the 700, 800 and 900F. sections were of a different color.

Changes in firmness of the sections are listed in Table 1. Slight changes
in firmness were found in the 800F. and 900F. samples at 3 months. A slight
change was found in the 70aF. sample in 1 year. The firm segments in the 900F.
sample at 12 months were tough and rubber-like while the soft sections were very
soft and mushy.

Changes in pectic substances. Due to the great variation in pectic sub-
stances from sample to sample, direct comparison and interpretation of individual
results was impossible; however, there appears to be a significant trend when all
results obtained from examining 15 samples (5 sample replications at 3-month in-
tervals) over a 9-month period are considered. Table 2 shows the percentage pec-
tin on a wet basis in the water-soluble, polyphosphate-soluble and sodium hydrox-
ide-soluble (protopectin) pectic fractions. The total AGA found was 59.26 mg.;
thus any percentage figure shown in the table multiplied by 59.26 would equal the
milligrams of AGA found for a particular analysis.

There was an overall trend toward less protopectin with longer storage times
or with higher storage temperatures. The 3-month samples had 12.02% of the total
AGA. This decreased to 10.78% at 6 months and 9.44% at 9 months. The control
samples held at 320F. for 3, 6 and 9 months had 9.03% of the total as compared
to 3.53% in the 900F. samples.

The water-soluble pectins increased stepwise with increase of storage temp-
erature, and ran from 2.531% at 320F. to 4.33% at 900F. A trend did not develop
with time of storage.

The polyphosphate-soluble pectins showed the same trend that was found in
the water-soluble fractions. The 320F. samples had 9.79% of the pectins. The
percentage increased with temperature to 12.02% pectin in the 900F. samples.

Because the syrup was drained off and discarded it is probable that some
pectic substances were lost. The relationships shown for pectin with respect to
temperature and time of storage therefore apply only to the sections at the
time of analysis.

Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
636a 9/27/55 RLH












TABLE 1
Changes occurring in canned grapefruit sections during storage

Storage Flavor Color Firmness
temperature .. . ... .
oF. 3-m 6-mo. 9o. o. 6-mo. 6-mo. 9-mo 12-mo 3-mo. 6-mo 9-mo. 12-mo.
32 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.3
None one None None None None None None None None None None

60 1.0 1.3 1.3 1.5 1.0 1.0 1.3 1.4 1.3 1.3 1.0 1.3
None None None None None None None None None None None None

70 1.3 1.5 1.8 2.5 1.0 1.3 1.3 2.3 1.5 1.3 1.0 2.3
None None Slight Slight None None None Slight None None None Slight

80 1.5 2.1 2.8 3.8 1.5 2.3 2.5 3.3 2.0 2.3 2.3 3.3
None Slight Marked Extreme None Slight Slight Marked Slight Slight Slight Marked

90 2.8 3.5 4.0 4.0 2.5 3.3 4.0 4.0 2.3 3.0 4.0 4.0
Marked Marked Extreme Extreme Slight Marked Extreme' Extreme Slight' Marked Extremej Extreme
________--- _____-_____-- -- -- __-- --- -- ____ ___________ __


Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
622 10//55-RLH











Changes occurring in


1Percentage of total pectin
Percentage of total pectin


TABLE 2
pectic substances in canned grapefruit sections during storage


in 15 samples examined.


Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
622a 10/4/55-RLH


Percentage of total pectin 1
Storage H20-soluble (NaP03)n-soluble NaOH-soluble
temperature ......... Su Sub
t3-mo. 6-mo. i9-mo. i Sub 3-mo. 6-mo. 9-mo. Sub 3-mo. 6-mo. 9-mo. Sub
total total total
f jO C? ci
0.% I %% % 1% % % % % % %
32 0.68 0.91 0.74 2.53 3.44 3.24 3.11 9.79 3.44 3.17 2.42 1 9.03

60 0.81 1.05 0.91 2.77 2.84i 3.31 3.31 9.46 2.13 2.63 1.85 6.61

70 1.05 0.98 0.98 3.01 3.71 3.38 3.11 10.20 2.84 2.26 2.05 7.15
80 0.98 1.22 0.98 3.18 2.97 3.92 3.58 10.47 1.99 1.88 2.05 5.92

90 1.35 1.49 1.49 4.33 3.71 3.92 4.39 12.02 1.62 0.84 1.07 3.53
Sub totals % 5.07 5.65 5.10 15.82 16.67 17.77 17.50 51.94 12.02 10.78 9.44 32,10
Total % 100.00






-3-


Summary. For maintenance of original good quality in canned grapefruit
sections, the products should be held at 700F. or lower, Marked changes that
result in lower quality in this product occurred at storage temperatures of 800F.
or above. Storage at 700F. of canned grapefruit sections, which are not to be
consumed until 6 months or more after packing would greatly help to maintain the
original quality of this product.

A general trend was noted in the changes in the pectic substances, although
there was considerable variation among samples. Protopectin decreased with
storage time and with increase of storage temperature. More water-soluble and
polyphosphate-s'oluble pectins were present in the samples held at the higher
temperatures.


Part 2 Effect of Date of Packing

Collection, storage and methods of examination. The samples of commercial
canned grapefruit sections used for this storage study were collected at inter-
vals of approximately 2 weeks, starting November 13, 1953 and continuing through
February 18, 1954, as indicated in Table 3. All of the samples were held at
320F.temperature until April 1, 1954 at which time they were transferred to 900F.
storage. For comparison purposes, control samples were held at 320F. All
samples and the control were examined monthly over a period of 6 months using the
same methods of examination as indicated in Part 1 of this report. Analyses for
pectinesterase activity and pectic substances in these products were not made.

Changes in flavor, color and firmness. At the beginning of the storage
period, April 1, grapefruit sections from 5 cans from each of the 8 packs were
compared and slight differences in quality were evident in some of the samples.
The color or firmness of the samples packed on or before December 11 and on
January 7 were slightly better than in the other packs.

Results reported in Table 3 for the 8 packs and the control sample are the
average values for each determination from the 6 monthly examinations. These
average values indicate the changes that occurred in the packs over the period of
six months; however, since they are averages, the degree of change as indicated
is slightly less than that shown by results obtained from only the final exami-
nation of the packs after storage at 900F. for 6 months.

The average values for total acidity in the packs, as shown in Table 3,
ranged from 0.71 to 1.27%; the total soluble solids varied from 16.6 to 19.10Brix
with Brix/acid ratios varying from 13.9 to 25.1; and the range in pH was very
small, 3.3 to 3.5. Differences in drained weight were slight.

The changes in total acidity in these packs of grapefruit sections during
the season should be noted. Those packed on November 13 had an average value for
the acidity of 0.92%; the acidity decreased to a minimum of 0.71% in the pack of
December 22, then again increased in the January packs to a maximum of 1.27%;
then there was a decrease to 0.98% in the last pack on February 18. These vari-
ations in acidity are similar to those observed and reported in grapefruit juices
extracted during a season from arsenated and nonarsenated fruit.
FloriAa Oitrus Experiment Station and Florida Citrus Commission,
Lake Alfred- Florida.
636b 9/27/55-RLH









TABLE 3
Effect of date of packing on the changes occurring in canned grapefruit sections during
storage at 900F. a

Packing dates 1953-54 Control b 11-13 11-27 12-11 12-22 1-7 1-22 2-4 2-18
Can type (b) Buffet Buffet Buffet 303 Buffet 303 303 303
Acid as citric, % 0.90 0.92 0.89 0.78 0.71 1.06 1.27 1.04 0.98
OBrix, 280C. 16.6 19.1 17.7 18.9 17.8 18.2 17.6 17.8 18.8
Brix/acid ratio 18.4 20.8 19.9 24.2 25.1 17.2 13.9 17.1 19.2
pH 3.4 3.4 3.4 3.5 3.5 3.4 3.3 3.3 3.4
Flavor 1.0 1.8 1.8 1.8 2.0 2.4 2.9 2.8 2.8
None Slight Slight Slight Slight Slight Marked Marked Marked

Color 1.0 1.4 1.5 1.4 1.9 2.0 2.7 2.8 2.7
None None Slight None Slight Slight Marked Marked Marked
Firmness 1.0 1.5 1.4 1.8 2.1 1.7 2.3 2.6 2.2
None Slight None Slight Slight Slight Slight Marked Slight

HCDM Color Values
Rd 26.2 25.6 24.7 24.6 24.6 23.9 24.0 24.2 24.4
a -7.4 -6.4 -6.3 -6.6 -6.6 -6.2 -5.8 -5.8 -6.0
b 16.0 16.2 16.0 15.8 16.4 15.3 16.0 16.4 16.7

Drained weight c, oz. 9.8 9.6 10.7 10.1 9.3 10.2 9.5 9.1 8.9


a Values are averages
3%


for each determination from monthly examinations over a period of 6 months.


Control used for each examination was stored at 320F. and consisted of 3-buffet cans packed 1-29-54
and 2-303 cans packed 2-11-54.


On basis of net contents of 16 oz. for comparative purposes.
Florida Citrus Experiment Station and Florida Citrus Commission,
Lake Alfred, Florida. 636d -9/28/55 RLH


w






-4-


Examination of the results, Table 3, of the organoleptic tests shows that
greater and significant changes occurred in both the flavor and color of the
products packed on and after January 22 than in the canned grapefruit sections
processed from November 13 through January 7. Apparently, the changes in both
flavor and color occurred at about the same rate. The Hunter t"al values, when
averaged, ranged from -7.4 for the control sample to -6.0 or less in the packs
obtained on and after January 22. This increase in the "a" values, corresponding
to an increase in redness, correlated with the changes in color of the samples as
observed visually. Significant differences were not evident in the average Hunter
"Rd" or "b" values. Changes in firmness of the sections were only slight except
in the pack of February 4.

The changes in quality, during storage at 900F. for 6 months of canned
grapefruit sections processed early in the packing season were found to be less
than in those packed during the latter part of the season; however, it should be
noted that the packs, in which changes were more marked, were of slightly lower
quality initially, as previously noted.


Conclusions should not be drawn on the
only one plant and during only one season.
currently continued using canned grapefruit
two plants during the 1954-55packing season


examination of these products from
Therefore, this study is being
sections that were collected from


Acknowledgment

The authors wish to thank Mr. P. H. Fish for his cooperation and helpful
suggestions and the Florida Division, California Packing Corporation, Tampa,
Florida, for supplying the canned grapefruit sections used in these investigations.




















Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
636c 9/27/55 RLH




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