Group Title: Citrus Station mimeo report - University of Florida Citrus Experiment Station ; CES 64-1
Title: Effect of calcium salts on the firmness of canned grapefruit sections
Full Citation
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 Material Information
Title: Effect of calcium salts on the firmness of canned grapefruit sections
Series Title: Citrus Station mimeo report
Physical Description: 4 leaves : ; 28 cm.
Language: English
Creator: Olsen, R. W
Barron, R. W
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: 1963
Subject: Canned grapefruit -- Quality -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
Bibliography: Includes bibliographical references (leaf 4).
Statement of Responsibility: R.W. Olsen and R.W. Barron and R.L. Huggart.
General Note: Caption title.
General Note: "October 8, 1963."
 Record Information
Bibliographic ID: UF00072413
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 75959150

Full Text

Citrus Station Mimeo Report CES 64-1
October 8, 1963

Effect of Calcium Salts on the Firmness of Canned Grapefruit Sections1

R. W. Olsen
University of Florida
Citrus Experiment Station
R. W. Barron and R. L. Huggart
Florida Citrus Commission
Lake Alfred, Florida

Canned grapefruit sections are the second major grapefruit product processed
in Florida. During the 1961-62 season about 3 million boxes of seedy grapefruit
were used in the production of canned grapefruit sections. Any means of improving
the quality of this product is important since it is anticipated that we will again
have an over production of seedy grapefruit once the effect of the 1962 freeze is

Sales of canned grapefruit sections in previous years have been partially
limited due to their high price resulting from high labor costs in producing this
product. The general use of automatic peeling machines and the possibility of
sectionizing and packing equipment being used in the near future should result in
lower labor cost. It is anticipated that greater consumer demand for canned
grapefruit sections may result if the retail price is reduced and the quality

The only published report, by Singleton (5), on the use of calcium salts to
firm grapefruit sections showed that calcium cyclamate would give favorable re-
sults depending on the date of packing. All other published reports deal with
other plant materials as with Kertesz (3) showing the effect of calcium on plant
tissue. Most of the literature concerning firming deals with tomato products as
described by Hamson (2) and Hall and Dennison (1).

Data obtained from this investigation will (a) show if various calcium salts
can be used to increase the firmness of commercially canned grapefruit sections
and thus improve their quality, (b) make it possible to pack grapefruit sections
over a longer period during the citrus season than is currently possible, (c) in-
crease consumer demand for this product of better quality which would result in
the utilization of more grapefruit, and (d) will help some processors who are
interested in packing dietetic canned grapefruit sections, using calcium cycla-
mate instead of sugar. Therefore, the effect of these calcium salts on the firm-
ness of sections is of importance.

1 Some financial assistance for this investigation was made by Abbott
Laboratories and American Maize-Products Company through the establishment of a
joint grant-in-aid.

Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
00-10/8/63 RWO


Description of Packs

Due to the great variability in the quality of grapefruit sections, even from
the same lot and variety of fruit, large packs must be processed for results of
any significance. To check the effect of the packing date on the firmness of the
canned sections, it was planned to process the following packs at 3 different
times during each citrus season, possibly during the period of December 1 to April
1. However, due to a late start in the 1961-62 season and the 1962 freeze during
the 1962-63 season, it was not possible to do this but another attempt will be
made to do so during the 1963-64 season.
1. Water pack (control for calcium cyclamate)
2. Water and calcium cyclamate pack
3. Sugar syrup pack (control)
h. Sugar syrup and calcium chloride pack
5. Sugar syrup and calcium lactate pack

Ten cases (24/303) of each of the packs were prepared.

The above five packs were all that could be processed in one day and hence
only one level of each chemical was used. The amount of calcium cyclamate used,
0.27% by weight of net contents, was suggested by Olsen (4), the calcium lactate
level, 0.25%, was supplied by American Maize-Products Company and the calcium
chloride level, 0.088%, from unpublished sources.

Preparation of Packs

Packs were prepared at a nearby cannery using commercial fruit, almost en-
tirely Duncan or seedy, and commercial processing methods. Only standard heat
treatment was used for practical reasons. In the preparation of the packs, the
empty cans were picked up a few days ahead so they could be coded on the bottom;
also, a wide black band was encircled on each can so as to more readily recognize
them as they came from the cooler. The appropriate liquid with or without the
added calcium salts was then filled into the cans. The cans were then taken to
the processing plant and placed directly on the line containing the standard
commercial syrup-filled cans and hence were scattered throughout the sectionizing
plant. The sectionizers were all told that these cans were to be filled exactly
as the normal pack since some companies have used banded cans for broken sections.
The filled cans were then taken as they came from the cooler, sorted and placed
in cases.

Examination of Packs

The texture of approximately 1000 sections from each pack was determined
after the products had been stored from 2 weeks to 1 month at 800F. (initial);
also, after storage for 4 and 8 months. The firmness was determined by sub-
jective examination and also, if possible, will be determined later by use of an
instrument, such as a shear-press, provided such an instrument can be designed
or purchased.

Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
OO-10/8/63 RWO


In the examination of the packs, the sections were examined individually and
sorted into firm and soft and/or ricey sections, with a count being made of each
type. The total weight of each type of section was also recorded as well as the
volume and weight of the drained liquid. Samples of each pack were given to the
U.S.D.A. Agricultural Marketing Service for grading.

As mentioned earlier, a late start resulted in only two packing dates during
the 1961-62 season, the packs being made in February and March of 1962. Exami-
nation of the calcium chloride and syrup pack, initially, and after storage for
4 and 8 months showed 96.1, 74.1, and 82.3% by count of firm sections, respect-
ively; the syrup or control pack contained 89.4, 68.3, and 59.8%, respectively.
Thus, the addition of calcium chloride gave very good results as far as firming
the sections, but both the A.M.S. and the Station taste panel graded down the
product because the calcium chloride imparted a bitter off-flavor to it. Hence,
it was decided to discontinue the use of calcium chloride in future packs.

In Table 1 are listed percentages by count of firm sections found in each of
the two water packs and two calcium cyclamate packs prepared during the 1961-62
season. It may be seen that the difference between the means (total column) of
the percentages of firm sections in the initial water packs and the calcium cy-
clamate and water packs is a little over 10%. This difference was found to be
statistically significant at the 5% level, as well as the difference between the
means of the packs stored for 4 months. Therefore, it is evident that calcium
cyclamate improved the firmness of the water pack for at least the first 4 months,
although this did not apply to the samples after storage for 8 months.

Data presented in Table 2 were obtained from the examination of syrup packs
(control) and syrup and calcium lactate packs prepared during both the 1961-62
and 1962-63 seasons. The packs from the latter season were processed in December
1962 and January 1963. It may be readily seen that the addition of calcium lac-
tate definitely improved the firmness of the sections; also, that although the
percentage of firm sections in all of the syrup packs declined 15.4% after stor-
age for 8 months at 80F., the percentage decrease of firm sections in all of the
calcium lactate and syrup packs was only 3.7%.

It was decided to drop the water packs as it seemed more logical to substi-
tute juice for water so as to prepare a better quality pack. Also, since the
calcium chloride and water pack was discontinued, it was decided to replace this
pack with one containing grapefruit juice, calcium cyclamate, and calcium lactate.
Results of the examination of such packs, processed during the 1962-63 season, are
shown in Table 3. Examination of the packs prepared on January 23, 1963, and
stored for 8 months had not been made when this paper was written. It is apparent
from the information in Table 3 that more data are necessary to show the effect of
addition of calcium cyclamate to juice on the firmness of canned grapefruit
sections. However, the pack containing juice, calcium cyclamate, and calcium
lactate does show an improvement in the firmness of the sections over both of the
other two packs.

Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
00-10/8/63 HWO

Table 1. Effect of calcium cyclamate on the firmness of canned grapefruit

Type of Water Calcium cyclamate
pack and water
Date packed Date packed
Storage at 2/8/62 3/29/62 Total 2/8/62 3/29/62 Total
80 F. Firm % by count Firm % by count
Initial 63.4h 8.6 56.0 74.2 59.5 66.8
4 months 31.7 29.0 30.3 42.3 33.6 37.9
8 months 27.4h 4b2 34.3 _28.7 42.7 35.7

Table 2. Effect of calcium lactate on the firmness of canned grapefruit sections
Type of Syrup Calcium lactate
pack and syrup
Date packed Date packed
Storage at 2/8/62 3/29/62 12/20/62 1/23/63 Total 2/8/62 3/29/62 12/20/62 1/23/63 Total
800 F. Firm % by count Firm % by count
Initial 89.4 76.3 75.1 78.4 79.8 94.5 83.3 78.9 89.3 86.5
4 months 68.3 63.4 66.8 82.5 70.3 73.6 74.5 85.3 93.5 81.7
8 months 59.8 76.3 57.0 64.4 84.5 85.8 78.2 82.8
* Eighth month examination of packs not yet completed.

Table 3. Effect of calcium salts on the firmness of canned grapefruit sections
Type of Juice Juice and Juice, calcium cyclamate,
pack calcium cyclamate and calcium lactate
Date packed Date packed Date packed
Storage at 12/20/62 1/23/63 Total 12/20/62 1/23/63 Total 12/20/62 1/23/63 Total
800 F. Firm % by count Firm % by count Firm % by count
Initial 50.3 59.8 55.1 t9.h 69.3 59.4 59.0 79.1 69.5
4 months 35.5 71.4 53.5 53.2 71.2 62.2 61.2 85.9 73.5
8 months 34.9 -- 38.8 -- 57.4 --
Eighth month examination of packs not yet completed.

Florida Citrus Experiment Station
and Florida Citrus Commission,-
Lake Alfred, Florida.
to00-10/8/63 WO

There were other characteristics of these various packs that were measured,
such as drained weight, 0 Brix of syrup, flavor, pH, and total acid, but it
appeared that the addition of the calcium salts, other than calcium chloride,
affected only the texture of the sections. The products packed with juice or
water, naturally, had a slightly greater drained weight over that of the syrup


The authors wish to thank Snively Groves, Inc. for their aid in the pro-
cessing of these packs, Also, to Joseph McAllister of the Agricultural
Marketing Service, U.S.D.A., for grading the sections and to Dr. F. W. Wenzel
for his part in all phases of the project.

Literature Cited

1. Hall, C. B. and R. A, Dennison. The relationship of firmness and pectin-
esterase activity of tomato fruits. Proc. Am. Soc. Hort. Sci., 75, 629

2. Hamson, A. R. Factors which condition firmness in tomatoes. Food Research,
17, 370 (1952).

3. Kertesz, Z, I. The effect of calcium in plant tissues. Canner, 88, 26

4. Olsen, R. W. Cyclamates in citrus products. Proc. Florida State Hort. Soc.,
73, 270 (1960).

5. Singleton, G.
Soc., 72, 263

Some recent work on citrus sections. Proc. Florida State Hort.

Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
400-10/8/63 WO

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