Title: Measurement of potential clarification and gelation in frozen orange concentrate
ALL VOLUMES CITATION PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00072344/00001
 Material Information
Title: Measurement of potential clarification and gelation in frozen orange concentrate
Series Title: Citrus Station mimeo series
Alternate Title: Prediction of stability by rapid method
Application of rapid method in commercial plants
Physical Description: 5, 3 leaves : ; 28 cm.
Language: English
Creator: Li, Kuang C
Maraulja, M. D
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: 1960
 Subjects
Subject: Frozen concentrated orange juice -- Quality -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: Kuang C. Li and M.D. Maraulja.
General Note: Caption title.
General Note: "September 21, 1960."
Funding: Citrus Station mimeo report ;
 Record Information
Bibliographic ID: UF00072344
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 75265598

Full Text




Citrus Station Mimeo Series 61-1
September 21, 1960

Measurement of Potential Clarification and Gelation in Frozen
Orange Concentratel

I. Prediction of Stability by Rapid Method
Kuang C. Li and M. D. Maraulja

There has long been an urgent need for rapid methods for predicting both
potential clarification and gelatin in commercial frozen orange concentrate.
Such methods should be aimed for use in quality control laboratories during
continuous production of concentrate in commercial plants prior to filling the
product into cans for freezing. Preliminary work on the development of a rapid
method for the prediction of cloud stability of frozen orange concentrate was
reported last year. This report will describe and discuss rapid analytical pro-
cedures which have been developed during the past year for predicting both the
cloud stability and potential gelation in frozen orange concentrate.


Experimental Procedures and Results

Development of rapid method for determining cloud stability and potential
relation. It is known that various complex factors are related to clarification
in orange concentrate. These same factors are also involved in gelation. Since
the action of pectinesterase on pectin in orange concentrate is one of the major
causative factors involved in both gelation and clarification, it was decided to
determine if some modification of the procedure previously developed for pre-
dicting the cloud stability could also be used for predicting the potential
gelation. It was found that there is a definite relationship between the degree
of gelation, which occurs in orange concentrate after storage and the difference
between the initial relative serum viscosity of the reconstituted juice and that
of the serum after the rapid test. Commercial 420 Brix frozen orange concentrate
packed in 6 oz. cans was used for this study.

Directions for rapid method for determining cloud stability and potential
relation. The 6 oz. sample of concentrate, if frozen, is thawed undisturbed in
running tap water for 30 minutes and then reconstituted with 3 volumes of dis-
tilled or deionized water. A 100 ml portion of the reconstituted juice is ad-
justed as rapidly as possible to a pH of 6.3 or other optimum reaction pH as
predetermined for concentrate from a particular plant; a pH meter is used and
4N NaOH is added while the juice is rapidly stirred mechanically with a glass or
stainless steel stirrer. The temperature of the juice should be at 800F. + 10F.
after the necessary amount of 4N NaOH has been added and kept at this temperature
during the reaction period. The reaction time is measured by starting a stop
watch as soon as the desired pH is reached, as indicated by the pH meter. The
mixture is constantly stirred but without further adjustment of pH. After exactly

1 Cooperative research by Florida Citrus Experiment Station and Florida Citrus
Commission, aided by a grant-in-aid from the Continental Can Company.

Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
997 f 9/21/60 KCL







-2-


10 minutes, 3 ml of glacial acetic acid is added rapidly with constant stirring
so as to stop the enzymic reaction and at the same time obtain a final pH in
the mixture of 3.9 4 0.1. A 50 ml portion of the test mixture is then centri-
fuged for 10 minutes along with a 50 ml portion of the original reconstituted ,
juice. After centrifug&tion, the Serui from both the test mixture and the juice
are decanted off through several layersof cheesecloth ahd theh their temperature
adjusted to 266C0 (78.8OF,). The relative serum viscosity of both the reconsti-
tuted juice and the test mixture are determined at 26oC. (78.86F.) using an
Ostwald pipette or viscometer, which has been standardized with distilled or,
deionized water at the same temperature. The relative viscosity 6f a liquid
such as juice serum, is the ratib of the time of flow for a defnhite volume of
the liquid through the Ostwald pipette and the time of flow for the same volume
of water. The degree of clarification in the serum from the test mixture is
also determined in the usual.mnher as percentage light transmittance using a
colorimeter, In this investigation samples were centrifuged for 10 minutes at
1400 rpm in an Internatiohal Centrifuge, Size 1, Type SBV. The colorimeter used
was a 402't Lumetron with 730 filter and 10 mm cell.

Determination of cloud stability in samples of commercial frozen orange
concentrate using rapid method. During the 1959-60 citrus season, 187
commercial samples of frozen orange concentrate were collected semi-monthly
from 23 Florida plants, so that some characteristics of these products could
be determined. (See Citrus Station Mimeo Series 61-7 which is included in
these reports). These samples were examined for cloud stability by the rapid
method and results compared with those obtained after storage of these products
for 96 hr. at 400F. Data obtained are summarized and shown in Table 1. When
the rapid method was used with reaction conditions of pH 6.5, 800F. and 10
minutes, the correlation of the results, indicating the degree of clarification,
was 897 when compared with those obtained after storage of the samples for 96 hr.
at 400F. It had been demonstrated previously that for best correlation between
results from the 2 methods, a different reaction pH would have to be used in
different plants. Data also given in Table 1 show that 98% correlation was ob-
tained when the optimum reaction pH for each of the plants was used. These
optimum pH values ranged from 6.2 to 6.8. When a reaction pH of 6.5 was used
for all of the samples, 100% correlation between the results after the rapid
test and after storage for 96 hr. at 400F. was obtained at only 15 of the plants.
However, 100% correlation was found at 20 of the 23 plants when different opti-
mum reaction pH values were used and there was only 1 sample from each of the
remaining 3 plants for which agreement between the 2 methods was not obtained.

Determination of potential relation in samples of commercial frozen orange
concentrate using rapid method. As previously mentioned, a relationship has
been established between the degree of gelation, which occurs when concentrate
is stored for 24 hr. at 800F., and the difference between the initial relative
serum viscosity of the reconstituted juice and that of the serum after the rapid
method. The relative serum viscosities of samples of commercial frozen concen-
trated orange juice collected from Florida plants during 2 citrus processing
seasons are reported in Table 2. The initial relative serum viscosities of the
reconstituted juices prepared from 187 samples of frozen orange concentrate,
collected during the 1959-60 season, ranged from 1.64 to 3.13. The relative
serum viscosities after the rapid test for cloud stability, using the optimum
reaction pH and 10 minutes at 800F., for these same samples ranged from 1.54
to 3.13.
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
997 g 9/21/60 KCL










Table 1. Correlation on individual plant basis between results using
rapid method and storage of samples for 96 hr. at 400F. for predicting
cloud stability of 187 commercial samples of frozen orange concentrate
Rapid method 10 minutes at 800F.
Total Correlation For best correlation
Plant number of pH Number of % pH Number of %
number samples samples samples
1 8. 6.5 8 100 6.8 8 100
2 9 6.5 5 56 6.4 8 89
3 8 6.5 6 75 6.3 8 100
4 10 6.5 7 70 6.3 10 100
5 7 6.5 2 29 6.2 7 100
6 9 6.5 9 100 6.3 9 100
7 7 6.5 5 71 6.4 6 86
8 3 6.5 1 33 6.2 3 100
9 8 6.5 8 100 6.6 8 100
10 7 6.5 6 86 6.3 6 86
11 7 6.5 5 71 6.2 7 100
12-23 104 6.5 104 100 6.5 104 100

Totals 187 166 89% 184 98%


Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
997 a 9/21/60 KCL












Table 2. Frequency distribution of relative serum viscosities of commercial
frozen concentrated orange juice collected from Florida processing plants
Midseason Late season Total
Relative samples % samples -% samples %
serum Season 1958-59 1959-60 1958-59 1959-60 1958-59 1959-60
viscosity2 Samples 113 98 76 89 189 187

1.60-1.99 10.7 24.5 32.9 54.0 19.8 38.5
2.00-2.39 48.2 59.2 56.6 43.8 51.5 51.9
2.40-2.79 31.2 10.2 10.5 2.2 22.8 6.4
2.80-3.19 5.4 6.1 0.0 0.0 3.3 3.2
3.20-3.59 3.6 0.0 0.0 0.0 2.1 0.0
3.60-3.99 0.9 0.0 0.0 0.0 0.5 0.0

1Samples collected semi-monthly from December through June, inclusively,
during each processing season.
2 Relative to deionized water at 260C. (78.80F.) using an Ostwald viscometer.
Data for 1958-59 season obtained by George H. Ezell.


Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
997 b 9/21/60 KCL










Data presented in Table 3 show (a) the degree of gelation or gel number for
20 commercial samples of frozen orange concentrate after storage for 24 hr. at
800F. and (b) the change in the relative serum viscosity after the rapid method,
using 10 minutes at 800F. and different reaction pH values. The relative serum
viscosities are multiplied by 100 for easy interpretation. The degree of gelation
in the samples after storage for 24 hr. at 800F. was determined visually by a
standard method described in Regulation 19 of the Florida Citrus Commission.

To obtain correlation between the degree of gelation after storage of the
concentrates for 24 hr. at 800F. and the change in relative serum viscosity
after the rapid method, it was found that different optimum reaction pHs had to"
be used for samples from different plants, as had been shown previously necessary
to obtain correlation between the degree of clarification after storage for 96
hr. at 400F. and that found after the rapid test. The scatter diagram shown in
Figure 1 indicates that a relationship exists between the degree of gelation or
gel number and the change in the relative serum viscosity after the rapid method
provided the optimum reaction pH for the individual plants is used in testing
samples from each of the Plants. There are 191 points on the scatter diagram
(Figure 1) of which 187 represent samples collected during the 1959-60 season
and which are located in the 0, 1, or 2 gel number areas. The other 4 points
located in the 3 gel number area also represent commercial frozen orange concen-
trates; 3 of these samples were collected during the 1958-59 season and 1 during
the 1959-60 season. With the exception of 4 points, the data plotted in Figure 1
indicate that the following relationship exists between the degree of gelation in
orange concentrate after storage for 24 hr. at 800F. and the change in the rela-
tive serum viscosity of the reconstituted juice after the rapid method for pre-
dicting potential gelation.

Degree of gelation Change in relative
or gel number serum viscosity X 100
0 or 1 +20 to -18
2 -19 to -30
3 or 4 -31 to -100
The data presented in Table 3 for 20 samples show the changes in relative
serum viscosity after the rapid test when different reaction pH values were used,
as well as the gel number indicated by this change in accordance with the re-
lationship shown above so that it may be compared with the gel number for the
sample after storage for 24 hr. at 800F.

A summary is given in Table 4 of the results obtained by using the rapid
method for predicting the potential gelation in the 187 samples of orange con-
centrate obtained from 23 commercial plants during the 1959-60 season. When
the rapid method was used with reaction conditions of pH 6.5, 800F. and 10
minutes, the correlation of the results, indicating the degree of gelation, was
85% when compared with those obtained after storage of the samples for 24 hr.
at 800F. However, 98% correlation was obtained when optimum pH values, ranging
from 6.2 to 6.8, for each of the plants were used. When a reaction pH of 6.5
was used for all of the samples, 100% correlation between the results after the
rapid test and after storage for 24 hr. at 800F. was obtained at only 10 of the
plants. However, 100% correlation was found at 19 of the 23 plants when different
optimum reaction pH values were used and there was only 1 sample from each of the
other 4 plants for which agreement between the 2 methods was not obtained.
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
997 q 9/21/60 KCL







Table 3. Comparison of results using rapid method with different pH values
of gelation of 20 commercial samples of frozen orange concentrate


for predicting the degree


1 Degree of gelation


Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
997 d 9/21/60 KCL


Initial
or after


storage
0-None
1-Very slight
2-Slight
3-Semi-gel
4-Solid gel


Based on change
in relative


serum viscosity


0 or 1 = +20 to
2 = -19 to
3 or 4 = -31 to


-18
-30
-100


Degree of gelationI
Gel number Rapid method 10 minutes at 800F.
Plant Sample after 24 hr. Change in Gel Change in Gel
number number at 800F. pH relative serum number pH relative serum number
viscosity X 100 indicated viscosity X 100 indicated
1 1 2 6.5 8 0 or 1 6.8 -23 2
2 2 1 6.5 -66 3 or 4 6.4 -18 0 or 1
3 3 2 6.5 -25 2 6.3 -18 0 or 1
4 1 6.5 -21 2 6.3 -15 0 or 1
5 2 6.5 -76 3 or 4 6.3 -25 2
4 6 1 6.5 -31 3 or 4 6.3 8 0 or 1
7 2 6.5 -75 3 or 4 6.3 -20 2
5 8 1 6.5 -45 3 or 4 6.2 -11 0 or 1
n 9 0 6.5 -29 2 6.2 + 2 0 or 1
6 10 1 6.5 -25 2 6.3 -16 0 or 1
11 2 6.5 -32 3 or 4 6.3 -21 2
7 12 1 6.5 -20 2 6.4 -18 0 or 1
8 13 1 6.5 -23 2 6.2 4 0 or 1
14 2 6.5 -42 3 or 4 6.2 -21 2
9 15 2 6.5 7 0 or 1 6.6 -20 2
10 16 2 6.5 -74 3 or 4 6.3 -32 3 or 4
S17 2 6.5 -87 3 or 4 6.3 -25 2
11 18 0 6.5 -28 2 6.2 +1 0 or 1
12 19 2 6.5 2 0 or 1 7.5 5 0 or 1
13 20 1 6.5 -59 3 or 4 6.3 -18 0 or 1









Table 4. Correlation on individual plant basis between results using
rapid method and storage of samples for 24 hr. at 800F. for predicting
degree of gelation of 187 commercial samples of frozen orange concentrate
Rapid method 10 minutes at 800F.
Total Correlation For best correlation
Plant number of pH Number of % pH Number of %
number samples samples samples

1 8 6.5 7 88 6.8 8 100
2 9 6.5 7 78 6.4 9 100
3 8 6.5 5 63 6.3 7 88
4 10 6.5 7 70 6.3 10 100
5 7 6.5 4 57 6.2 7 100
6 9 6.5 6 67 6.3 9 100
7 7 6.5 4 57 6.4 7 100
8 3 6.5 0 0 6.2 3 100
9 8 6.5 7 88 6.6 8 100
10 7 6.5 5 72 6.3 6 86
11 7 6.5 5 72 6.2 7 100
12 12 6.5 11 92 6.5 11 92
13 5 6.5 4 80 6.5 4 80
14-23 87 6.5 87 100 6.5 87 100

Totals 187 159 85% 183 98%


Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
997 c 9/21/60 KCL










Use of rapid method for predicting both cloud stability and potential
elation. From the data accumulated during this investigation, it has become
evident that when the degree of clarification after the rapid method is found
to be the same as that after storage of the concentrate for 96 hr. at 400F.,
then almost always the degree of gelation indicated by the rapid method will
correspond to that found in the concentrate after storage for 24 hr. at 800F.
This is important because it usually makes possible the prediction of both the
cloud stability and the potential gelation of a concentrate by the use of the
same rapid procedure together with the determination of the cloud in the serum
and the relative serum viscosity. It is believed that the test can be conducted
in from 30 to 45 minutes. Data reported in Table 5 illustrate how the rapid
method can predict both the cloud stability and the potential gelation of a con-
centrate, providing the proper reaction pH is used. The degree of clarification
and the gel number indicated by the rapid method for samples A, B, D, E and I
correspond to those found after storage at 400 and 800F. when the reaction pH
values were 6.8, 6.3, 6.4, 6.3, and 6.5, respectively. However, for samples C,
F, G, and H different reaction pH values had to be used in the same plant to
obtain agreement between the results from storage tests and either the cloud
stability or the potential gelation as determined by the rapid method. These
4 samples were the only products in the 187 samples of orange concentrate tested
which showed these irregularities, but it was thought advisable that such ex-
ceptions should be pointed out.


Discussion of Results
A rapid method has been developed and described for predicting both the
cloud stability and potential gelation of orange concentrate. The method is
primarily based upon adjusting the pH of the reconstituted juice, for example
to pH 6.5, so that the rate of reaction of pectinesterase on the pectin in the
juice will be increased to such an extent that the degree of clarification re-
sulting in 10 minutes at 800F. will correspond to that which occurs when 420
Brix concentrate is stored for 96 hr. at 40oF. After readjusting the pH of the
juice to 3.9, the degree of clarification in the centrifuged reconstituted pro-
duct is determined as percentage light transmittance using a colorimeter. The
initial relative serum viscosity of the reconstituted juice and that of the test
mixture after the rapid method are also determined, since it was found that a
change occurred in this characteristic whenever clarification and/or gelation
were evident. Such a change in the relative serum viscosity can be used to
predict potential gelation in 420 Brix orange concentrate because a relationship
was established between the degree of gelation when the concentrate was stored
for 24 hr. at 800F. and the change in the relative serum viscosity after the
rapid method. A decrease in the relative serum viscosity when clarification
and/or gelation occurs is chiefly caused by the removal of soluble pectin from
the juice serum following its demethylation by pectinesterase and the precipi-
tation of the demethylated pectin after its combination with calcium or other
bivalent metallic ions.

Since many factors are involved in the clarification and gelation of orange
concentrates, such as pectinesterase activity and the quantity and quality of

Florida Citrus Eperiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
997 r 9/21/60 KCL










Table 5. Comparison of results using rapid method
cloud stability and degree of gelation of 9 commercial


with different pH values for predicting both
samples of frozen orange concentrate


Degree of Rapid method 10 minutes at 800F. Degree of
Sample clarification Degree of Change in Gel gelation
after 96 hr. pH clarification relative serum number after 24 hr.
at 400F. viscosity X 100 indicated** at 800F.
A 31-none 6.5 37-none 8 0 or 1 2-slight
i I 6.8* 42-none -23 2 "
B 36-none 6.5 57-none -32 3 or 4 1-very slight
SI 66.3* 40-none -10 0 or 1 "
C 67-slight 6.5 71-definite -25 2 2-slight
I I 6.3* 60-slight -18 0 or 1 "
D 61-slight 6.5 97-extreme -66 3 or 4 1-very slight
S______6.4* 64-slight -18 O or 1 "
E 36-none 6.5 95-extreme -75 3 or 4 2-slight
If i" 6.3* 46-none -20 2 I
F 87-extreme 6.5 98-extreme -74 3 or 4 2-slight
,I 6.3* 76-definite -32 3 or 4 "
G 54-none 6.5* 30-none 2 0 or 1 2-slight
"t 7.5 31-none 5 O or 1 "
H 72-definite 6.5* 80-definite -59 3 or 4 1-very slight
6.4 54-none -34 3 or 4 "
I" 6.3 40-none -18 0 or 1 i
I 82-definite 6.5 73-definite -17 0 or 1 1-very slight
6.4* 68-slight 9 0 or 1 "

SpH for best correlation for all samples for plant from which this sample was obtained.
** See footnote on Table 3.
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
997 e 9/21/60 KCL








-5-


pectin, together with many other conditions which affect these factors, it is
remarkable that the data, obtained from the examination of 187 samples of
commercial frozen orange concentrate, show that when the optimum reaction pH
values were used with a reaction time of 10 minutes at 800F., 98o% correlation
was possible between results from the rapid method and those for the degree of
clarification found in the samples after storage for 96 hr. at 400F.; also 98%
correlation for the degree of gelation was found for the samples after storage
for 24 hr. at 800F.

It should be emphasized that in using this rapid method conditions of pH,
temperature and time must be carefully and accurately controlled if reproducible
and reliable data are to be obtained. As previously pointed out optimum pH
conditions for the rapid method will have to be determined for each plant so
that maximum agreement between the current plant tests for clarification and
gelation and the rapid method may be obtained. It is also important that the
relative serum viscosity be determined at exactly 2600. (78.80F.) since a small
change in temperature will result in a relatively large change in viscosity.

It is suggested that during the 1960-61 season the rapid method be tried
in quality control laboratories of concentrate plants, along with the usual
storage methods used by individual plants for measuring cloud stability and
potential gelation. By so doing comparable data may be obtained to determine
the reliability of the rapid method and find out if it is suitable for quality
control during the continuous production of commercial orange concentrate.


























Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
997 s 9/21/60 KCL




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