• The Korean Journal of Food And Nutrition
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• v.10 no.1
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• pp.92-96
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• 1997

A Korean commercial sweet rice drink "Sikhye" showed sucrose, fructose, glucose, maltose, limit dextrin and various size of maltooligosaccharides in HPLC and TLC analysis. Commercial Sikhye was found to contain 0.09% of limit dextrin and 0.2% of rice residue. Limit dextrin in commercial Sikhye showed both signal of $\alpha$-1,4- and $\alpha$-1,6-glucosidic linkage with its estimation ratio of 15:1 by 1H-NMR analysis. This limit dextrin was hydrolyzed to produce various size of maltooligosaccarides with more longer chain than that of traditional Sikhye by pullulanase. Limit dextrin was digested wit enzymes(30units/ml) of $\alpha$-amylase, $\alpha$-glucosidase and glucoamylase from Aspergillus awamori, sweet potato $\beta$-amylase and human salivary $\alpha$-amylase at 37$^{\circ}C$ for 1 hour, respectively. Hydrolysis rates of these amylases on it were higher than in case of traditional sikhye. $\alpha$-Glucosidase plus human salivary $\alpha$-amylase hydrolyzed it to 61.3%. Hydrolysis rates of these amylases on rice residue were lower than that of traditional Sikye. These results suggest that limit dextrin in commercial Sikhye is less effective than isomaltooligosaccharides in traditional Sikhye as a growth factor for Bifidobacterium while rice residue in commercial Sikhye is more effective than that in traditional Sikhye as dietary fiber.ary fiber.

• The Korean Journal of Food And Nutrition
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• v.10 no.2
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• pp.180-185
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• 1997

Sikye was produced from glutinous rice. The glutinous rice Sikhye was found to contain 7.3% of limit dextrin, 10.1% of maltose, 1.3% of maltotriose and 1.75% of rice residue. Limit dextrin in glutinous rice Sikhye was purified by ethanol fractionation followed by gel chromatography on Biogel P-2. The purified limit dextrin showed both signal of $\alpha$-1,4- and $\alpha$-1,6-glucosidic linkage with its estimation ratio of 5:1 by 1H-NMR analysis. Limit dextrin was digested with enzymes(30units/ml) of $\alpha$-amylase, $\alpha$-glucosidase and glucoamylase from Aspergillus awamori, sweet potato $\beta$-amylase and human salivary $\alpha$-amylase at 37$^{\circ}C$ for 1 hour, respectively. Hydrolysis rates of these amylases on it were similar that of rice Sikhye. $\alpha$-Glucosidase plus human salivary $\alpha$-amylase hydrolyzed it to 18%. The results suggest that glutinous rice is more effective to produce high level of branched maltooligosaccharide compared with rice as raw material for Sikye making.

• Korean Journal of Food Science and Technology
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• v.27 no.4
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• pp.631-634
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• 1995

Some structural characteristics of hot-water insoluble rice starch [3 varieties of Japonica type and 3 varieties of Tongil type(Japonica-Indica breeding type)]were investigated. The amylose contents of hot-water insoluble starches were 2.7-6.1%. The chain distributions of hot-water insoluble starches were composed of super long chain of above ${\overline{DP}}\;55$ (31.9-38.7%), B chain of ${\overline{DP}}\;40-50$ (12.3-18.0%) and A chain of ${\overline{DP}}\;10-20$ (48.5-50.4%). The chain distributions of hot-water insoluble starches and their ${\beta}-limit$ dextrin were difference between rice varieties and their were differ from those of amylopectin and their ${\beta}-limit$ dextrin. these result suggest that hot-water insolubility of rice starch was showed its characteristic on the varieties and it be responsible for the molecular structure of amylopectin.

• Journal of Microbiology and Biotechnology
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• v.29 no.3
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• pp.357-366
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• 2019

We first confirmed the involvement of MalQ (4-${\alpha}$-glucanotransferase) in Escherichia coli glycogen breakdown by both in vitro and in vivo assays. In vivo tests of the knock-out mutant, ${\Delta}malQ$, showed that glycogen slowly decreased after the stationary phase compared to the wild-type strain, indicating the involvement of MalQ in glycogen degradation. In vitro assays incubated glycogen-mimic substrate, branched cyclodextrin (maltotetraosyl-${\beta}$-CD: G4-${\beta}$-CD) and glycogen phosphorylase (GlgP)-limit dextrin with a set of variable combinations of E. coli enzymes, including GlgX (debranching enzyme), MalP (maltodextrin phosphorylase), GlgP and MalQ. In the absence of GlgP, the reaction of MalP, GlgX and MalQ on substrates produced glucose-1-P (glc-1-P) 3-fold faster than without MalQ. The results revealed that MalQ led to disproportionate G4 released from GlgP-limit dextrin to another acceptor, G4, which is phosphorylated by MalP. In contrast, in the absence of MalP, the reaction of GlgX, GlgP and MalQ resulted in a 1.6-fold increased production of glc-1-P than without MalQ. The result indicated that the G4-branch chains of GlgP-limit dextrin are released by GlgX hydrolysis, and then MalQ transfers the resultant G4 either to another branch chain or another G4 that can immediately be phosphorylated into glc-1-P by GlgP. Thus, we propose a model of two possible MalQ-involved pathways in glycogen degradation. The operon structure of MalP-defecting enterobacteria strongly supports the involvement of MalQ and GlgP as alternative pathways in glycogen degradation.

• YAKHAK HOEJI
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• v.6 no.2
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• pp.18-22
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• 1962

Purified preparation of .betha.-amylase is obtained from radish root by the means of fractional precipitation with ammonium sulfate. Purified preparation saccharifies the starch, .betha.-maltose being formed. Dextrinization in the true sense does not take place. Hydrolysis ceases when approximately 50% of the theoretical yield of maltose is obtained and there remains a substance (to be .betha.-limit dextrin) which gives a blue-violet with iodine, no glucose being formed. Stability of preparation is optimal at pH 4-9 and more completely inactivated at 65.deg. in fifteen minutes. .betha.-Amylase of radish exhibits optimal activity at and near pH 5.0, which varied depending upon the buffer. Calcium and chloride ions do not effect the activities of enzyme. The results of experiments with oxidizing, alkylating and mercaptide-forming reagents which have been reported to be specific for sulfhydryl groups confirm that free sulfhydryl groups are essential to the activity of .betha.-amylase from radish.

• Applied Biological Chemistry
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• v.43 no.4
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• pp.241-246
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• 2000

In order to investigate structural properties of Chindo black rice(grown in Chindo, Chonnam) starch and its amylopectin, Chindo black rice was investigated in comparison to Shinsun waxy rice. The maximum absorbance wave and intrinsic viscosity of Chindo black rice starch and Shinsun waxy rice starch were 523 nm, 521 nm and 183 ml/g, 178 ml/g, respectively. ${\beta}-amylolysis$ limit(%) of Chindo black rice and Shinsun waxy rice starch were 62.8% and 60.3%, respectively. Chindo black rice was determined to be a waxy rice due to the results of iodine reaction and elution profile on Sephroce CL-2B. The chain of amylopectins in Chindo black rice distributed fraction 1$(F_1)$ of above degree of polymerization$({\overline{DP}})$ 55, fraction 2$(F_2)$ of ${\overline{DP}} $40{\sim}50$ and fraction 3$(F_3)$ of ${\overline{DP}} $15{\sim}20$, and the ratio of $F_3$ to $F_2$ for Chindo black rice was higher than that for Shinsun waxy rice. The super long chain of amylopectin in Chindo black rice was consisted much more than that of Shinsun waxy rice. ${\beta}-limit$ dextrins in Chindo black rice amylopectin distributed $F_1$ of above ${\overline{DP}} 55, $F_2$ of ${\overline{DP}} $30{\sim}45$ and $F_3$ of ${\overline{DP}} $10{\sim}20$. Little difference was shown between elution patterns of the pullulanase treated ${\beta}-limit$ dextrins of Chindo black rice amylopectin and Shinsun waxy rice amylopectin. These results suggest that Chindo black rice starch was similar to Shinsun waxy rice starch.

• Korean Journal of Food Science and Technology
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• v.21 no.1
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• pp.80-85
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• 1989

The structural properties of covered and naked barley starches and those components were investigated. ${\beta}-amylosis\;limit(%)$ of covered and naked barley starches were 58.6 and 56.3%, respectively and those of their amyloses and amylopectins were 87.0, 77.7, 57.6 and 52.0%, respectively. The ratios of outer chain length ${\overline{OCL}}$ and inner chain length${\overline{ICL}}$ for amylopectins of covered and naked barley were about 2.2:1 and 2.0:1, respectively. The elution curves by Sephadex G-75 after debranching starches with pullulanase were similar patterns for two starches and yielded two peaks consisting of amylose component${\overline{dp}}>55$ and bimodal amylopectin components of ${\overline{dp}_(35-45)$ and ${\overline{dp}}(10-20)$ hydrolysates. Also, hydrolysis products by sequential hydrolysis with pullulanase and ${\beta}-amylase$ contained 0.03-0.5% non-hydrolyzed peak components of ${\overline{dp}}>55$. The elution profiles of ${\beta}-amylase$ hydrolysates yielded two peaks consisting of the inner components${\overline{dp}}>55$ and the outer chain components of amylopectin${\overline{dp}}>10$ regardless of samples. However, ${\overline{dp}}$ distributions of ${\overline{dp}>55}$ hydrolysates exhibited the significant differences due to the varieties.

• Korean Journal of Food Science and Technology
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• v.27 no.1
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• pp.105-111
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• 1995

The relationship betwwen the molecular structure of amylopectin and the texture of cooked rice was investigated using Korean rice [3 varieties of Japonica type and 3 varieties of Tongil type(Japonica-Indica breeding type)]. The molecular structure of rice amylopectin was polymodal and distributed A chain of $\overline{DP}$ 12.4, short B chain of $\overline{DP}$ 20.6, B chain of $\overline{DP}$ 26.3, long B chain of $\overline{DP}$ 45 and super long chain of above $\overline{DP}$ 55. The super long chain of amylopectin was composed of long linear chain with poorly branched chain. Also, the super long chain of amylopectin showed positive correlated with average chain length, inherent viscosity and ${\beta}-amyloysis$ limit$({\%})$, but negative correlated with ${\lambda}max$ of iodine reaction of amylopectin. The structural properties of amylopectin in Japonica type were different from those of amylopectin in Tongil type. In relationship between molecular structure of amylopectin and texture of cooked rice, the average chain length, inherent viscosity, ${\beta}-amyloysis$ limit and super long chain of amylopectin was showed a positive correlation with hardness, but a negative correlation with adhesiveness of cooked rice. The long chain of rice amylopectin is the less, the eating quality of cooled rice was the better. These results suggest that the molecular structure of rice amylopectin could be responsible for the texture of cooked rice.