Group Title: Citrus Station mimeo report - Florida Experiment Station ; 56-6
Title: Preliminary study of relationship of fertilizer and spray practices on the quality of canned grapefruit sections
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 Material Information
Title: Preliminary study of relationship of fertilizer and spray practices on the quality of canned grapefruit sections
Series Title: Citrus Station mimeo report
Physical Description: 4 leaves : ; 28 cm.
Language: English
Creator: Wenzel, F. W
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 -- Quality -- Florida   ( lcsh )
Grapefruit -- Fertilizers -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: F.W. Wenzel ... et al..
General Note: Caption title.
General Note: "October 4, 1955."
 Record Information
Bibliographic ID: UF00072375
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 74716970

Full Text

Citrus Station Mimeo Report 56-6
October 4, 1955


Preliminary Study of Relationship of Fertilizer and Spray Practices on
the Quality of Canned Grapefruit Sections
F. W. Wenzel, R. L. Huggart, J. W. Sites, E. J. Deszyck, E. L. Moore,
R. W. Barron and R. W. Olsen


The quality of citrus fruits is affected by many factors, including fertili-
zer and spray practices. Sites mentioned the importance of rootstock, soil, and
weather conditions and presented data showing the effect of fruit variety, ferti-
lizer practices, use of oil, parathion, and lead arsenate sprays, irrigation and
size of fruit on the internal quality of citrus fruits as indicated by changes in
soluble solids, acidity, vitamin C and juice yield.

The Florida pack of canned grapefruit sections have averaged about 4 1/4
million cases (24/2's) each year during the last 5 seasons. During the 1954-55
season over 3 1/2 million boxes of grapefruit were used for canning about 6 mil-
lion cases of grapefruit sections and salads, which corresponded to 26% of the
total seedy grapefruit utilized. The quality of canned grapefruit sections, which
is one of the factors that determines consumer acceptance and future demand, is
dependent upon the quality of the fresh fruit utilized and therefore is also de-
pendent upon any of the many factors which cause changes in the internal quality
of fruit.

Little information is available concerning the importance of fertilizer and
spray practices in influencing the quality of canned grapefruit sections. There-
fore, the preliminary studies discussed in this report represent an effort to
find out if variations in the amounts of potassium or magnesium in fertilizers
used or if the arsenation of grapefruit would cause differences in the quality of
canned grapefruit sections.

It should be emphasized that because of the many other factors involved in
this investigation, besides the variables just indicated, it is impossible to
draw conclusions on the basis of results obtained to date. The purpose of this
report is to present the data that were obtained, which definitely indicate that
further investigation will be necessary if the principal factors affecting the
quality of canned grapefruit sections are to be determined, so that such infor-
mation may be utilized in the production of grapefruit to be used for this pro-
duct.

Source of Fruit. Dunoan grapefruit was obtained from plots in Station
Block 5. The fertilizer applied to these plots since 1939 has contained the
equivalent of 3%N, 6% P205, 3% MgO, 1% MnO, 1/2% CuO together with variable
amounts of K20. Fruit from plots, No. 6, 1 and 2, treated with fertilizers hav-
ing the equivalent of 0, 3 and 10% K20 was processed on February 12, 1954; fruit
picked the following season was processed on February 26, 1955.

1
Sites, J. W. Some factors affecting the quality of citrus fruits. CitrYs
Station Mimeo Report 54-7. Presented at Fourth Annual Citrus Processor~~
Meeting, Lake Alfred, Fla. Oct. 6, 1953. ,
Florida Citrus Experiment Station
and Florida Citrus Commission, 3
Lake Alfred, Florida.
642 9/30/55 FWW




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Walters grapefruit from plots, No. 2, 3 and 4, in Station Block 9 were
sectionized and processed on the same dates. The fertilizer used on these plots
since 1938 contained the equivalent of either 0, 2 and 4% MgO and 4%N, 6% P205,
8% K20, 1% MnO and 1% CuO.

Fruit used on February 12, 1954 to determine the effect of arsenation was
seedy grapefruit obtained from trees in Block 4 which had been sprayed with
either 1-1/4 or 7-1/2 lb./l00 gal. of lead arsenate (PbHAsO4) spray. Fruit that
had not been arsenated was processed as a control. In 1955 grapefruit for this
study was not available from Block 4 and therefore two lots of seedy grapefruit
from Block 19 were used, one of which was not arsenated and the other had been
treated with 1-1/4 lb./l00 gal. lead arsenate. The same fertilizer and spray
practices, other than arsenation, have been used in both Block 4 and 19 since
1953.

After picking all of the lots of fruit were held for 3 to 4 days before pro-
cessing. The size of the fruit varied considerably and it was not possible to
use fruit of only one or two sized because in some instances the amount of fruit
available was limited.

Canning of Grapefruit Sections. Usual commercial procedures for the peeling,
sectionizing and processing of grapefruit sections were used. The sections
canned on February 12, 1954, were processed at the Tampa plant of the Florida
Division, California Packing Corporation; the following season the sections were
canned on February 26, 1955 at the Winter Haven plant of Bordo Products Company.
Yield data are not presented since the individual lots of fruit used were very
small, approximately 5 boxes; also it was decided that only the packs of whole
sections would be examined and so the cans of broken sections obtained were dis-
carded. Packs of the canned whole grapefruit sections were stored at 800F. at
the Station until examined.

Examination of Canned Grapefruit Sections. All of the products packed on
February 12, 1954 were examined at the Station during the period March 30 to
April 5, 1954; those packed on February 26, 1955 were examined from May 25 to
June 1, 1955. A good quality commercial pack obtained from the commercial plants
in 1954 and 1955 were also examined for comparison purposes. Samples of the 1955
packs were inspected and graded at the plant immediately after packing and again
after 2 weeks by Mr. Walter D. Pond, U.S.D.A., Agricultural Marketing Service
(AMS).

Methods of examination and grading used at the Station were different from
those used by the AMS and therefore will be described. The number of size 303
cans of sections used from each pack is listed in Tables 1, 2 and 3; the sections
from about one-half of the total number of cans in each pack were examined indi-
vidually. The sections from each can were drained on either a 10 or 16 mesh
screen for 2 min. and then examined individually to see if a "thread" was present
on the section and to divide the sections into three groups on the basis of firm-
ness, namely whole sections, sections that broke on handling and soft sections.
The sections in each of these groups were weighed to obtain the total drained
weight. The drained syrup from the cans in each pack was mixed together and the
acid, soluble solids, pH and total glucosides as naringin in this syrup were de-
termined.

Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
642a 9/30/55 FWW





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Finally, the quality of each pack was rated as either good, fair or poor on the
basis of the firmness, as well as general appearance or character.

Results and Discussion. Results from the examination of the 17 experimental
packs of canned grapefruit sections are shown in Tables 1, 2, 3 and 4. Informa-
tion on two commercial packs of good quality are also included in Tables 1, 2 and
3 for comparison purposes.

Information in Table 1 shows that the quality rating of canned sections de-
creased in the 1954 packs as the amount of potassium in the fertilizer used was
increased; the number of whole sections in these packs was 68, 48 and 28% and the
number of soft sections was 6, 19 and 42% of the total number of sections when the
K20 level was 0, 3 and 10F. In the 1955 packs prepared from fruit from the same
grove plots this trend was not evident since all of the sections in the 3 packs
were of poor quality, containing from 32 to 45% of the total number of sections
that were soft.

In 1954, when the MgO level was 4%, these canned sections were only slightly
better in quality than those in the other packs of this group (Table 2); this
pack contained a smaller percentage of whole and soft sections, but a larger num-
ber of sections that broke when handled. The packs processed from fruit from
these same plots in 1955 contained large percentages of soft sections and were of
poor quality.

As indicated in Table 3, the use in 1954 of arsenated grapefruit from Station
Block 4 resulted in lower quality in the canned sections than in those prepared
from fruit that had not been arsenated. However, exactly the opposite results
were found in 1955 when arsenated and nonarsenated grapefruit were used from
Station Block 19. Such results illustrate both the complexity of the problem and
perhaps why some differences of opinion exist in the industry concerning the
effect on the quality of canned sections when arsenated grapefruit is used. No
logical explanation for these results has been found.

The difference in the firmness of the sections in the two packs made from
arsenated and nonarsenated fruit (Table 3) processed on February 26, 1955, was
very marked. The firmness of grapefruit sections is probably related to their
protopectin content. The prevention of the enzymic conversion of insoluble pro-
to pectin to other more soluble pectic substances by an inhibitor, such as lead
arsenate, may be suggested as a possible cause in this instance for increased
firmness in sections from arsenated fruit. An investigation of the pectic sub-
stances in fresh and canned grapefruit sections from arsenated and nonarsenated
fruit has been planned to obtain some information on this subject.

The percentage of the sections, examined from the various packs, which had a
"thread" is indicated in Tables 1, 2 and 3. The "thread" is the main vascular
bundle traversing the dorsal side of the segment. Since each of the juice.sacs
is attached to this "thread", it was suggested that perhaps a section having the
"thread" would not break apart as easily as one without the "thread". This in-
formation was obtained since the question had been asked as to the possibility of
the decreased occurrence of this "thread" in canned sections because of cultural
practices. A greater percentage of the sections from the 1955 packs had a "thread"

Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
642b 9/30/55 FW












Effect of Quantity of


Table 1
Potassium in Fertilizer Used on the Firmness of


Canned Grapefruit Sections

Variation No. of No. of "Thread" jFirmness- % Final Acid as
in potassium 303 cans sections i present Whole Broke on Soft rating citric, %
as K20 examined examined % handling
asK2_ -------_ ; :
Processed February 12, 1954

SK20 None 83 1190 79 68 26 6 Good 0.82

SK20 % 107 1659 78 48 33 19 Fair 1.07
20 10% 95 1594 64 28 30 42 Poor 1.25

Commercial 36 652 57 51 48 1 Good 0.94
pack
Processed February 26, 1955
K20 None 64 1147 86 47 17 36 Poor 1.00
K20 3% 66 1227 86 47 21 32 Poor 1.08
K20 10% 62 1204 83 39 16 45 Poor 1.22
Commercial 48 876 89 42 51 7 Good 1.01
pack I
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
639 9/28/55-FWW









Table 2
Effect of Quantity of Magnesium in Fertilizer Used on the Firmness of
Canned Grapefruit Sections

Variation No. of No. of "Thread" Firmness % Final Acid as
in magnesium 303 cans sections present Whole Broke on Soft i rating citric, %
as MgO examined examined _% _1 handling__
Processed February 12, 1954 __
MgO None j 82 1316 71 42 41 17 Poor 0.73
MgO 2 95 1527 67 32 46 22 Poor 0.82
MgO 4% 101 1510 67 i 26 65 9 Fair 0.79
Commercial 36 652 57 51 48 1 Good 0.94
pack
Processed February 26, 1955

MgO None 81 1358 81 43 27 30 Poor 1.12
MgO 2% 92 1182 86 30 31 39 Poor 1.01
MgO 4% 87 1266 83 36 28 36 Poor 1.16
Commercial 48 876 89 42 51 7 Good 1.01
pack _

Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
639a 9/28/55 FWW









Table 3
Firmness of Canned Grapefruit Sections Processed from Arsenated Fruit

Variation in No. of No. of "Thread" Firmness % Final j Acid as
lead arsenate 303 cans sections present Whole Broke on I Soft rating citric, %
in spray, examined examined % handling
lb./100 gal. _____ _
Fruit from Station Block 4 Processed February 12, 1954
None 101 1577 67 61 32 7 Good 1.14
1-1/4 lb. 77 1264 69 52 35 13 Fair 0.90
7-1/2 lb. 82 1169 62 33 49 18 Fair 0.71
Commercial 36 652 57 51 48 1 Good 0.94
pack

Fruit from Station Block 19 Processed February 26, 1955
None 62 734 89 8 33 59 Poor 1.01

1-1/4 lb. 100 1343 91 56 35 9 Good 0.91
Commercial 48 876 89 42 51 7 Good 1.01
pack

.Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
639b 9/28/55 FWW









Effect of Fertilizer


Table 4
and Spray Practices on the Quality of Canned Grapefruit Sections


Fertilizer No. of 303 cans Drained weight No. of sections Wholeness Final Final
or spray examined 1 per can oz. per can % Score rating grade
treatment Station AMS Station AMS Station AMS Station AMS Station AMS
All Packs Processed February 26, 1955
K20 None 64 6 9.3 10.0 18 21 47 18 Poor B

K20 3% 66 6 8.9 9.8 19 21 47 18 Poor B
K20 l 62 6 8.6 9.6 19 20 39 18 Poor B


MgO None 81 8 9.5 10.0 17 17 43 18 Poor B
MgO 2% 92 9 8.7 9.5 13 14 30 18 Poor B
MgO 87 7 9.2 9.9 :15 16 36 17 Poor SStd


Not
arsenated 62 6 9.0 9.3 12 13 8 17 Poor SStd
Arsenated
1-1/4 lb. 100 10 9.7 10.0 13 15 56 20 Good A
per 100 gal.
ft -, ,, 6,,


Examined at Station about 3 months after packing;
Agricultural Marketing Service, Winter Haven, FloI
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
639c 9/28/55 --FW


graded 2 weeks after packing by Walter D. Pond, U.S.D.A.,






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than those from the 1954 packs and on the basis of the 81% or greater frequency
found in the 1955 packs, it seems that the occurrence of the "thread" was not de-
pendent upon the fertilizer or spray practices considered in this study.

Analytical results from the examination of the syrup drained from the
sections in each pack showed a range in pH from 3.2 to 3.8. The acidity in the
syrups from the sections showed the usual trends found in grapefruit when it is
either arsenated or when the amount of potassium in the fertilizer used is varied.
The total glucosides, as naringin, in the syrups from the 1954 experimental packs
ranged from 38 mg./lO0 ml. (7-1/2 lb./l0 gal. lead arsenate) to 68 mg./l0 ml.
(0% K20 level); the syrup from the commercial pack examined in 1954 had a naringin
content of 29 mg./l0 ml.

The final quality rating, based upon the examination at the Station, and the
final AMS grades for the 1955 packs are given in Table 4; also shown in informa-
tion about the drained weight and number of sections per can for these experiment-
al packs.

In summary, the results of this investigation indicate that the amount of
potassium or magnesium in the fertilizer used and arsenation of grapefruit may be
factors that will effect the quality of canned grapefruit sections; however, on
the basis of the data obtained conclusions can not yet be made. Further study of
this problem is needed and in any future investigation as many variables as possi-
ble should be eliminated and the study should extend for a period of from 3 to 5
years.


Acknowledgments

Thanks are expressed to the Florida Division, California Packing Corporation,
Tampa, and to the Bordo Products Company, Winter Haven, for providing their
facilities and personnel which made possible the canning of the grapefruit sections
for this study. The cooperation of Mr. P. H. Fish and Mr. J. D. Tidwell was also
appreciated.
















Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
642o 9/30/55 FWW




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