practical study of jelly processing to utilize immature
TRANSCRIPT
[Comment]
Practical Study of Jelly Processing to Utilize Immature
Satsuma Mandarin Fruits
Tadao Inazu and Yoshio Makino
Immature Satsuma mandarin fruits, containing larger amount of organic acids (citric acid ca. 3times, malic acid ca. 5 times) than the mature ones, were used for making jelly. The jelly was
produced by controlling concentrations of organic acid, sugar and gelling agent (carrageenan). Theratio of the gelling agent to the total weight of the jelly was mathematically determined from therelationship between carrageenan concentrations and breaking stress values of the jelly. There wasno significant different of the taste between immature and mature mandarin fruit jellies. Theutilization of the immature fruits is effective for saving amount of the juice needed for the jellymaking. Jelly making is a feasible method to employ the immature Satsuma mandarin fruit.
Keywords: Immature fruit, Citrus, Jelly, Satsuma mandarin
INTRODUCTION
Satsuma mandarin is one of the most favorable
fruits in Japan. In general, 90% of the mandarin
fruits have been thinned during growing process to
obtain high quality fruits and to maintain produc-
tion yield1'2). Yield of thinned immature mandarin
fruits is estimated to be 18 ton per hectare, which
have been wasted as a useless material. The wasted
fruits have been desirable to be used as a bio-
material resource from a point of material utiliza-
tion.
Dohi et al .3) reported that the immature mandarin
fruits were useful as a flavoring resource for sponge
cake and citrus vinegar. They suggested the possi-
bility of application of the immature mandarin for
food processing. However, to utilize a large amount
of the immature mandarin fruits as a food resource,
the other application methods are needed to be
found.
In the present study, the immature Satsuma mandarin juice was applied to jelly making which is
one of the most important application methods of
fruit juice by controlling concentrations of chemical
components and by adding gelling agent. Concentra-tion of the gelling agent was mathematically deter-
mined from the relationship between carrageenan
concentrations and breaking stress values of a jelly.
Usefulness of immature Satsuma mandarin for jelly
processing was discussed.
MATERIALS AND METHODS
1. Test fruits Three kinds of the immature Satsuma mandarin
fruits, Okitsu (early maturing variety, 32 years old) ,
Kuno (medium maturing variety, 27 years old) ,
Hayashi (late maturing variety, 36 years old) were
sampled as test plots at Kagawa Agricultural Experiment Station (Fuchu branch, Kagawa Prefec-
tural Government, Japan) on August 15th, 1995. The
mature mandarin fruits of the same types of variety
as described above were sampled as control plots at
the same Station (harvest date : Okitsu November
* Food Research Institute , Kagawa Prefectural Government ** Kagawa Prefectural Fermentation & Food Experimental
Station
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Practical Study of Jelly Processing to Utilize Immature Satsuma Mandarin Fruits
17th, Kuno November 27th, Hayashi December 13
th) .
2. Preparation of fruit juice
One hundred immature Satsuma mandarin fruits
were washed by water, cut in two pieces, and sque-ezed to extract juice with a throttle (VITAM
PRESS 2, made in Italy) . The obtained juice was
centrifuged (10 min, 5,000 rpm) and filtrated
through a membrane (average pore size 5 pm) to remove suspended pulp. Thirty mature Satsuma
mandarin fruits were also treated by the same
method as above. This treatment was conducted on
each variety. The six types of the juice obtained
were presented for chemical analysis and jelly making.
3. Chemical analysis
Mean weight per fruit and extract juice yield
(weight ratio of extracted juice to a fruit) were determined. pH (HM-30 V, TOA Electronics, Inc.,
Tokyo, Japan) , Brix (PR-100, measurable range :
Brix 0-32%, ATAGO, Inc., Tokyo, Japan) , organic
acid concentration, and sugar concentration of the
juice obtained from six types of mandarin fruit were also determined. Organic acid concentration was
measured by high pressure liquid chromatography
(HPLC) system (Shodex LC DG-1, Showa Denko, Inc., Tokyo, Japan) , Shodex M 315 UV/VIS detec-
tor (Showa Denko, Inc.,) under the following condi-
tions : Shodex KC-811 column (Showa Denko,
Inc.,) , column temperature of 50°C, developer of
3 mM-HCI04, linear flow rate of 1 ml/min, and wavelength of 430nm, respectively. Sugar concen-
tration was also measured by HPLC system with
GLC-611 column (Hitachi, Inc., Tokyo, Japan) , R 401 differential refractometer (Waters Japan,
Inc., Tokyo, Japan) under the following conditions
column temperatue of 60°C, developer of 1 x 10 N-
NaOH, and flow rate of 1 ml/ min, respectively. 4. Jelly making
Before jelly making, sugar concentration of each
juice was adjusted to Brix value of 19.0% by controlling weight ratio of juice, sucrose, fructose,
and glucose to total weight of solution because that
commercial jelly with carrageenan was reported to have 19g sucrose per 100g jelly4). Organic acid
concentration (citric acid plus malic acid) of each
immature mandarin juice was adjusted to the same
concentrations as each mature one by dilution with distilled water. Carrageenan concentration was
determined by the procedure described in the later
sub-section "Concentration of carrageenen". Mix-
ture of each juice and carrageenan were heated up to 80°C to dissolve the carrageenan. 40 ml portions
of the heated mixture were divided into pudding
cases and cooled at 6°C in a refrigerator for gela-
tion. 5. Concentration of carrageenan
To determine the carrageenan concentration in
jellies, 0.66%, 0.72%, 0.78%, or 0.84% (w/w) of the carrageenan agent (Oruno CW8, Takeda Chemical
Industries, Inc., Tokyo, Japan) was added to a sugar
solution (adjusted to Brix value 19.0% using
granulated sugar) . The four types of carrageenan solution were heated up to 80°C, and then cooled in
a refrigerator for gelation. The jelly prepared was
cut in a rectangular prism (area 400 mm', thickness 10 mm) , and the prism was presented to breaking
stress measurement with a creep meter (Rheoner
RE-33005, Yamaden, Inc., Tokyo, Japan) by the
compression method according to Kohyama and Nishinari5). This rheological measurement was con-
ducted under the following conditions : diameter of
circular plunger was 40 mm ; compression speed
was 1mm/sec ; and clearance was 1 mm, respective-ly. The carrageenan concentration and breaking
stress data were analyzed by a least squares method
using a microcomputer with Delta graph® Pro 3
(Nippon Polaroid, Inc., Tokyo, Japan) . Statistical analysis was conducted by Fisher's z-transforma-tion method using Stat View® 4.02 (Abacus con-
cepts, Inc., Berkeley, USA) . The breaking stress of
a standard carrageenan jelly which is widely dis-
tributed to commercial market in Japan (mandarin orange taste, Morinaga Nyugyo, Inc., Tokyo,
Japan) was measured according to the same method as described above. These measurements were
repeated 16 times. 6. Sensory test
Sensory test was done to evaluate differences of
sweetness, sourness, and synthetic taste between the
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J. Cookery Sci. Jpn. Vol. 30 No. 3 (1997)
immature and mature fruit jellies by the two step
rank method with fifteen panelers (in our Institute) .
The jellies stored at 6°C were submitted to the test,
and the rank sum data obtained was analyzed according to Kramer's method°.
RESULTS AND DISCUSSION
1. Chemical component of juice
The mean weight per fruit and the extract juice
yield were presented in Table 1. The concentrations of organic acids and sugars in the six types of the
juice were also indicated in Table 1. The mean weight data per immature fruit were in the range of
14.7 to 21.2g, which were 80.0-106.8g lighter than
those per mature one. The extract yield data of the immature fruit juice were in the range of ca. 27 to 34
%, which were 13.5-18.1% lower than those of the mature one. This is because the mature mandarin
fruit possesses a larger amount of bulk sap than the
immature one (the amount of the sap per fruit is
proportional to largeness of the fruit). The concen-trations of citric acid and malic acid in the im-
mature mandarin juice were in the range of 3.69 to
3.98% and 0.16 to 0.18%, respectively, which were
about 3 times and 4-6 times higher than those in the mature one, respectively. The pH values of the
immature mandarin juice were in the range of 2.57
to 2.65, which were 0.65-0.83 lower than those of
the mature one. Kakiuchi et al.') reported that Satsuma mandarin fruit had much free acid chiefly
composed of the citric acid (over 90%) and the
malic acid. They also presented that the concentra-
tions of these organic acids rapidly rises at early stage of fruit growth (from August to September in
Japan) , and rapidly falls at medium stage of fruit
growth (from the end of September to the beginning of October) . The organic acid concentration falls
down to ca. 1% at late stage (from November to December) of fruit growth'. The great difference of
organic acid concentrations between the immature
and mature mandarin juice in the present study was
probably due to the difference of the growing stage when the fruits were harvested (August and Decem-ber, respectively).
Sucrose, fructose and glucose, which are the main
sugars in a mandarin fruit, were reported to
increase rapidly with accumulation of fruit sap". Kakiuchi et al. presented that the fructose and the
glucose in the mandarin fruit increased before the medium stage of fruit growth (beginning of Octo-
ber) , and that sucrose increases after the medium
stage. In the present experiment, sucrose concentra-tions in mature mandarin juice were 3-4 times
higher than those in the immature one as presented
in Table 1. The concentrations of the fructose and
the glucose in the mature mandarin juice were 1.7- 2.0, and 1.5-1.9 times higher than those in the
immature one, respectively. This indicates that the
sucrose increases more rapidly than the fructose
and the glucose in the mandarin fruit, and that the
sugar components are dependent on the harvest time of the mandarin fruit.
2. Jelly making
Table 2 indicates the weight component per 100g
jelly produced and the concentrations of sugar and organic acid after mixing. To adjust the sugar
concentration to be equal (Brix value 19.0%)
between the immature and the mature fruit jellies,
Table 1. Characteristics of Satsuma mandarin juice
* Weight ratio of extracted juice to a fruit.
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Practical Study of Jelly Processing to Utilize Immature Satsuma Mandarin Fruits
Table 2. Materials used for jelly making
* Carrageenan. ** Except carrageenen.
more sucrose, fructose and glucose were added to
immature mandarin juice than those to mature one.
Gordon') and Owada et a1.° reported that taste of fruit juice was affected by ratio of sugar concentra-
tion to organic acid concentration in juice, and that
high concentration of the organic acid in the juice
caused depression of preference of the juice. The
sugar and organic acid concentrations in each im-mature mandarin juice therefore are controlled to
the same concentrations as the mature one before
gelation from a taste point of view. 3. Concentration of carrageenan and break-
ing stress of a jelly
Rheological property of various polysaccharide
gels, such as pectiC), agarose, K-and A-car-rageenan, curdlan"), and agar12), is generally char-
acterized by a brittle breaking. The statement is
applied to the result obtained in the present experi-
ment as shown in Fig. 1. When the breaking load
g (x) [N], the deformation x [m], the thickness of sample L [m], and the cross section area A [m2] are
obtained, the breaking strain E[m/m] and the brea-
king stress P (e) [N/m2] can be expressed by Eq. (1)
and (2) as follows: E= X / L Eq. ( 1 )
P (E) =g(x)/ A Eq. ( 2 )
Omura et a1.'2 presented that the breaking stress
increased with an increase in the agar concetration
or with a rise in the compression speed. In the
present experiment, the breaking stress was mea-sured under the constant compression speed in-
dependent of the carrageenan concentretion in a
Fig. 1 A typical stress-strain curve of a carrageenan gel under the carrageenan concentration of 0.77% and
compression speed of lmm/sec. Symbol (0) breaking point, E breaking strain, P (E) breaking stress.
jelly. Fig. 2 shows the relationship between the carrageenan concentrations and breaking stress
values of jellies produced by the method presented in sub-section "Concentration of carrageenan". The
breking stress increased with an increase in the
carrageenan concentration in the jelly. This sug-
gests that the breaking stress is a function of the carrageenan concentration. We propose the follow-ing exponential type equation to express the rela-
tionship between the breaking stress and car-
rageenan concentration: P (E) BexP (k . c) Eq. ( 3 )
where c is the carrageenan concentration in a jelly
PAL B[N/m2] and Ic[%-'] are the constants. The
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J. Cookay Sci. Jpn. Vol. 30 No. 3 (1997)
Fig. 2 Relationship between carrageenan concentration and breaking stress of jellies. Symbols
(0) denote experimental data as a mean±standard deviation of 16 breaking stress values. Solid line
denotes the best fit line.
experimental data agreed with the calculated values
as shown in Fig. 2 (correlation coefficient 0.938,
statistically significant over 99.9% level) when B and k were 59.1 N/m2 and 6.92%-', respectively.
The values of the constants were calculated by the
least squares method. To determine the car-
rageenan concentration of the jelly in the present
experiment, the breaking stress of a marketing jelly was measured. The mean value of the breaking
stress of the marketing jelly was 12.5 x 103N/m2
which corresponded to the carrageenan concentra-
tion of 0.77% according to Eq. (3) . This value of carrageenan concentration was applied to the fruit
jelly making in this experiment. 4. Sensory test and suitable jelly component
Sensory scores of the mandarin fruit jelly were
presented in Table 3. A significant difference of the sensory scores expressing sweetness, sourness, or
synthetic taste between immature and mature man-
darin fruit jellies was not found. This suggests that
a jelly made from an immature mandarin juice has almost equal taste to that from a mature one, and
that the immature mandarin fruit may be useful for
jelly making as well as the mature one. The difference between Brix value and sum of concen-tration of sucrose, fructose and glucose is presumed
to be mainly caused by starch. The difference is
Table 3. Sensory score (rank sum) for
Satsuma mandarin jelly*
* All scores have no significant difference between the immature and mature mandarin jelly.
assumed to be sensuously neglected because sweet-
ness of starch is much weaker than that of the
sugars. The breaking stress of mandarin fruit jelly including sugar and organic acid may be different
from the stress of the jelly made in sub-section "Concentration of carrageenan" 13) However, the
lifference does not affect the results of sensory test. The breaking stress values between the immature
and the mature fruit jellies are equal because both
jellies include the same concentrations of sugar and
prganic acid. The suitable weight of the mature and
mmature mandarin juice and that of the mandarin ruits for making 100g jelly estimated from the
2xtract yield (Table 1) were presented in Table 4.
The weights of the immature mandarin juice and 'ruits needed for jelly making are ca . 1/3 (30.1-34.6
)/) and ca . 1/2 (46.3-57.7%) of the weights of the nature one, respectively. The extract yield of the
mmature mandarin juice is lower than that of the
Table 4. Weights of Satsuma mandarin juice and fruit needed for production of 100g jelly*
The values designated in parentheses indicate the
ratios in %.
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Practical Study of Jelly Processing to Utilize Immature Satsuma Mandarin Fruits
mature one as shown in Table 1. However, high
concentration of the organic acid in the immature
fruit is useful for saving the amount of juice needed
for the jelly making. The sugar concentration in the
immature mandarin juice is lower than that of the
mature one. This does not seems to be a disadvanta-
geous factor in the jelly making process because sugar is generally added to the mandarin fruit juice
in the industrial procedure of the jelly making.
From a practical point of view, the immature
mandarin fruit may be more useful for the jelly
making than the mature one because the cost of
organic acid is higher than tht of sugar. Moreover,
the utilization of the wasted material like immature
fruits is desirable from an economical point of view.
From these results and discussion, we concluded
that the immature Satsuma mandarin fruits was
useful enough for the jelly making.
ACKNOWLEDGMENTS
Thanks to Dr. Ken-ichi Iwasaki in our institute
for the support to this study.
REFERENCES
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3) Dohi, S., Tezuka, M., Motosugi, M., Shimono, K. and Furuhashi, M.: Reports of the Shizuoka Prefec-
tural Industrial Technology Center., 31, 125 (1986) 4) Resources council, Science and technology agency,
Japan. : Standard tables of food composition in Japan. 4th ed, p. 70 (1982) Printing bureau ministry
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Sci. Technol., 39, 715 (1992) 6) Kahan, G., Coorer, D., Papavasiliou, A. and
Kramer, A.: Food Technol., 27, 61 (1973) 7) Kakiuchi, N., Iba, Y. and Ito, S.: Bulletin of the
Horticultural research station., B10, 149 (1970) 8) Gordon, J.: J. Food Sci., 30, 903 (1965) 9) Owada, T., lino, K., Ishima, T. and Yoshikawa, S. :
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摘果 ミカンを利用 したゼ リーの製造
稲津忠雄 牧野義雄
キ ー ワ ー ド : 摘 果 果 実 , か ん き つ , ゼ リ ー , 温 州 ミ カ ン
廃棄物 であ る摘 果 ミカ ンの有効 利 用 を図 るため に,そ
の果 汁 を用 い てゼ リー の試作 を行 った。温州 ミカ ンは
早生 品種(興 津),中 生 品種(久 能),晩 生 品種(林)
の3種 類 を用 いた。 試作 ゼ リー のゲ ル強度 は,ゲ ル化
剤 の添加率 と破 断応 力値 か ら構築 した関係 式 に よ り,
市販 品 と同 じ強度 に調整 した。摘 果 ミカン果 汁は完 熟
果 汁に比べ て糖 含 量が低 か った(シ ョ糖 で1/4,果 糖 で
1/2,ブドウ糖で1/2)が,逆に酸含量は高かった(ク
エ ン酸 で3倍,リ ン ゴ酸 で5倍)。 摘果 及 び完熟 果汁 か
ら成分 調整 して作 られ たゼ リー は,甘 さ,酸 っぱ さ,
お い しさの3項 目につ い て比較 した。 その結果,両 者
の 間に有 意差 は認 め られず,同 等の 品質 を持つ ゼ リー
が製 造 で きた。摘 果 ミカンは高 い酸含 量 の ため に,ゼ
リー 製造 に要 す る使 用 果 汁量 を節約 で き,こ れ を利 用
した方 が製造効 率 の 点 で有 利 で あ り,未 利用 資源 の活
用 に もな るこ とが明 らか に なっ た。
(平成9年2月28日 受理)*香 川県食品試験場
**香 川県発酵食品試験場
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