Group Title: Citrus Station mimeo report - Florida Citrus Experiment Station ; 55-5
Title: Changes in sugar composition of juice of citrus fruits during maturation
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Permanent Link: http://ufdc.ufl.edu/UF00072366/00001
 Material Information
Title: Changes in sugar composition of juice of citrus fruits during maturation
Series Title: Citrus Station mimeo report
Physical Description: 2, 2 leaves : ; 28 cm.
Language: English
Creator: Ting, S. V., 1918-
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: 1954
 Subjects
Subject: Citrus juices -- Composition -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Includes bibliographical references (leaf 2).
Statement of Responsibility: S.V. Ting.
General Note: Caption title.
General Note: "Oct. 12, 1954."
 Record Information
Bibliographic ID: UF00072366
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 74327945

Full Text


Citrus Station Mimeo Report 55-5
Oct. 12, 1954


Changes in Sugar Composition of Juice of Citrus
Fruits During Maturation
S. V. Ting

Total soluble solid content of the juice has been used generally as one of
the criteria for the determination of maturity of citrus fruits. The sweet taste
of the juice, however, is not due to the total soluble solids per se but rather
to the quantity and quality of the sugars in the juice. Total sugars usually
occupy between 70 and 85% of the total soluble solids of the juice. The other
soluble components are mainly organic acids (chiefly citric acid) and their salts,
soluble nitrogenous substances and pectic materials.

The sugar constituents of Valencia orange and Marsh grapefruit juice have
been recently identified by McCready et al. (2) to contain only three sugars:
namely, glucose, fructose, and sucrose. By the use of the recently developed
technique of paper chromatography the sugars of Hamlin and Pineapple oranges,
Marsh grapefruit, and Dancy tangerine were qualitatively identified to be the
same.

In most literature dealing with the quantitative studies of sugars of citrus
fruits, no differentiation was made between glucose and fructose partly due to a
lack of convenient methods for the selective determination of one in the presence
of the other. The development of a rapid colorimetric method in our laboratory
for the simultaneous determination of total reducing sugars and fructose facili-
tated the study of the sugar components in the juice of various kinds of citrus
fruits during maturation.

With the amount of each of the 3 sugars known, it becomes possible to calcu-
late a numerical designation of relative sweetness of the juice by using the
relative sweetness indices of sugars by Biester, et al. (1). They assumed the
sweetening power of sucrose to be 100 and compared those of the other sugars
accordingly. Not all sugars have the same sweetening power. According to these
authors, fructose has a relative sweetness index of 173.3 while glucose has only
74.3.

The seasonal changes in sugar composition of the juices of oranges and tan-
gerine are shown in Table 1. In general sucrose and total reducing sugars in-
creased as all fruits ripened. The increase in sucrose was much more pronounced
in the early and mid season varieties than in Valencia. There was a significant
increase of glucose and a slight decrease of fructose with successively later
pickings in the early and midseason varieties. The changes of these 2 sugars
in the late variety were less evident.

The ratio of sucrose to total reducing sugars was much greater in the earlier
varieties than in Valencia, especially as the season advanced.

The total reducing sugars of the tangerine were relatively low as compared
to those of oranges and did not change significantly throughout the season, while
the sucrose increased. The increase in total sugar content was contributed mainly

Florida Citrus Experiment Station and
Florida Citrus Commission, Lake Alfred, Fla.
533 10/12/54 SVT






-2-


by the increase of that sugar, while fructose and glucose remained rather con-
stant.

The data in Table 2 show that with the exception that the total sugars of
grapefruit juice tend to increase as the fruit matured, there was no significant
pattern according to which the sugars of grapefruit juice changed at different
stages of maturity. The ratio of sucrose to total reducing sugars in all in-
stances was lower than 1, while in the case of tangerine and oranges it was great-
er than 1.

The relative sweetness indices of all juice samples were calculated and are
shown in the last column of Tables 1 and 2. The relative sweetness of juices of
oranges and tangerine showed a consistent increase as the fruit ripened. In
grapefruit, there was no significant change in these indices except in the variety,
Excelsior, where a slight increase was shown.


Literature Cited

1. Biester, Alice, Wood, M. W., and Wahlin, C. S. Carbohydrate studies I. The
relative sweetness of pure sugars. Amer. J. Physiol., 72, 387-396 (1925).

2. McCready, R. M., Walter, E. D., and Maclay, W. D. Sugars of citrus juices.
Food Technol., _, 19-20 (1950).



























Florida Citrus Experiment Station and
Florida Citrus Commission, Lake Alfred, Fla.
533a 10/12/54 SVT









TABLE 1
Seasonal changes in sugar composition of juices of oranges and tangerine

Date of Total Total Relative index
picking Glucose Fructose reducing Sucrose sugars of sweetness
sugars


September
October
November
November

November
December
January
January

January
February
March
March
April
May
May

September
October
October
November
November
December
December


1.17
1.32
1.56
1.64

.96
1.34
1.78
.2.00


1.74
1.96
1.97
2.29
2.14
2.13

1.19
1.12
1.24
1.37
1.02
1.03
1.09


2.26
2.09
1.98
2.01

2.86
2.78
2.64
2.55


2.44
2.36
2.46
2.55
2.59
2.49

1.55
1.55
1.49
1.50
1.58
1.50
1.54


Florida Citrus Experiment Station and
Flo.rida Citrus Commission, Lake Alfred,
533b 10/12/54 SVT


Hamlin orange
3.43
3.41
3.54
3.65
Pineapple orange
3.82
4.12
4.42
4.55
Valencia orange
4.13
4.18
4.32
4.43
4.84
4.73
4.62
Dancy tangerine
2.74
2.67
2.73
2.87
2.60
2.53
2.63


Fla.


4.16
4.29
4.71
5.35

4.96
5.61
6.09
6.51

4.19
4.31
4.50
5.04
4.95
4.95
5.13

2.19
2.88
3.64
4.25
4.97
4.99
4.64


7.59
7.70
8.25
9.00

8.78
9.73
10.51
11.06

8.32
8.49
8.82
9.47
9.79
9.68
9.75

4.93
5.55
6.37
7.12
7.57
7.52
7.27


893.6
888.2
929.0
1004.1

1061.8
1141.1
1197.4
1240.1


981.9
1003.3
1075.4
1105.6
1101.4
1101.4

575.2
639.0
713.5
785.9
845.8
834.7
811.1









TABLE 2
Seasonal changes in sugar composition of juices of grapefruit

Date of Total Total Relative index
picking Glucose Fructose reducing Sucrose sugars of sweetness
sugars


September
October
November
November
December
January
January

August
September
September
October
October
November
November
December

September
October
November

September
October
November


1.58
1.68
1.85
1.83
2.03
1.86
1.82

1.60
1.70
1.83
2.05
1.76
1.79
2.24
2.03

1.55
1.75
1.67

1.57
1.43
1.68


1.84
2.23
2.23
2.22
2.50
2.46
2.37

2.00
1.93
2.06
2.07
1.89
2.10
2.00
2.16

1.71
1.78
1.76

1.65
1.67
1.94


Excelsior
3.42
3.91
4.08
4.05
4.53
4.32
4.19
Ruby Red
3.60
3.63
3.89
4.12
3.65
3.89
4.24
4.19
Marsh
3.26
3.53
3.43
Duncan
3.22
3.09
3.62


Florida Citrus Experiment Station and
Florida Citrus Commission, Lake Alfred, Fla.
533r 10/12/54 SVT


2.64
2.93
2.70
3.08
2.65
3.01
2.67

3.34
3.39
3.07
2.97
2.71
3.19
2.96
2.96

2.62
2,59
2.47

2.87
2.80
3.08


6.06
6.84
6.78
7.13
7.18
7.33
6.86

6.94
7.02
6.96
7.09
6.36
7.08
7.20
7.15

5.88
6.12
5.90

6.09
5.89
6.69


699.2
803.1
792,7
829.0
847.8
864.2
811.7

798.4
798.7
798.8
806.8
728.2
814.8
807.8
819.9

672.5
696.4
675.1

688.6
674.7
767.9




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