Amylose was prepared by enzymatic polymerization of alpha-D-glucose 1-phosphate dipotassium catalyzed by a phosphorylase using two kinds of the primers derived from maltopentaose, and then it was chemically bonded to silica gel to be used as a chiral stationary phase (CSP) in high-performance liquid chromatography. In method I, maltopentaose was first lactonized and allowed to react with (3-aminopropyl)triethoxysilane to form an amide bond. Amylose chains with a desired chain length and a narrow molecular weight distribution were then constructed by the enzymatic polymerization. The resulting amylose bearing a trialkoxysilyl group at the terminal was allowed to react with silica gel for immobilization. In method II, maltopentaose was first oxidized to form a potassium gluconate at the reducing terminal. After the enzymatic polymerization was performed with the potassium gluconate, the amylose end was lactonized to be immobilized to 3-aminopropyl-silanized silica gel through amide bond formation. Two amylose-conjugated silica gels thus obtained were treated with a large excess of 3,5-dimethylphenyl isocyanate to convert hydroxy groups of amylose to corresponding carbamate residues. The CSP derived through method II was superior in chiral recognition to the CSP derived from method I and showed better resolving power and higher durability against solvents such as tetrahydrofuran compared with a coated-type CSP. Influences of degree of polymerization of amylose, the spacer length between amylose and silica gel, and mobile phase compositions on chiral recognition were investigated.

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Cereal Chem. 83(4):439-446An improved method for the extraction of storage proteins from rice endosperm under conditions safe for producing food was developed. The contribution of the protein extracts to the eating quality of cooked rice and to the aroma and flavor of sake was examined. Sensory analysis was performed to evaluate the eating quality of cooked rice enriched with the protein extracts. Prolamin-enrichment increased the hardness of cooked rice, and glutelin-enrichment degraded the appearance of cooked rice. Physical analyses confirmed that prolamin-enrichment changed, whereas the glutelin-enrichment did not change the physical properties of cooked rice. Light and scanning electron microscopy of rice protein extracts revealed small particles of the prolamin extract and larger aggregated particles of the glutelin extract; these features remained after heating. The aroma and flavor of sake were negatively affected by the addition of the protein extracts. Especially, addition of prolamin significantly lowered the evaluation score of the aroma obtained by sensory analysis.

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To investigate the suitability of low-amylose rice cultivars for sake brewing, weanalyzed physicochemical properties, and carried out small scale sake brewing and a Koji making test,with normal rice cultivars serving as controls.Important findings in this study are:(1) low-amylose rice the cultivars had a superior water absorption;(2)Dynamic modulus(G')of steamed rice of low-amylose rice cultivars was lower than in controls;in low-amylose rice cultivars,water content of polished rice does not greatly affect the Dynamic modulus (G') of steamed rice;(3)low-amylose rice cultivars exhibited a characteristic in which the digestibility of retrograded steamed rice was more difficult to lower in comparison with the controls,and there was a remarkable difference in low-amyloserice cultivars;(4) in the sake brewing test,the fermentation profiles of low-amylose rice cultivars was good,the amount of a sake cake of low-amylose rice cultivars at the end of fermentation was less,sensory score is the highest when using Chugoku173 as the rice material;and (5) in the koji making test,the results of acid protease and acid carboxy peptidase activity measurements showed a difference between low-amylose rice cultivars and normal rice cultivars.From the above results, we conclude thatlow-amylose rice cultivars are very suitable for sake brewing.