Katsuharu Yasumatsu

Studies on Cereals

Five carbonyl compounds were found in the vapour of cooked rice, of which acetaldehyde, and n-caproaldehyde were identified from their retention times in gas chromatography and by their infrared spectra. Propionaldehyde or acetone, methylethylketone, and n-valeraldehyde were tentatively identified. The mechanisms of the formation of these carbonyl compounds were discussed from the view-point of Strecker degradation and lipid oxidation.When stored rice (40°C, two months) was cooked, the stale flavor (komai-shu) was clearly detected by sensory test. Direct gas chromatographic analysis of head space vapors over cooked rice showed three main peaks which corresponded to propionaldehyde or acetone, n-valeraldehyde and n-caproaldehyde. On the other hand, the content of linoleic and linolenic acids of the rice decreased during storage at 40°C. This means that the unsaturated fatty acids autoxidized during storage and gave rise to carbonyl compounds responsible for the stale flavor of cooked rice.

Studies on the Functional Properties of Food-grade Soybean Products: Part I. Classification of Soybean Products by their Chemical Constituents and Protein Properties

Knowledges on chemical constituents and protein properties are fundamental prerequisites for the discussion of functional properties of food-grade soybean products. Chemical analysis was made on 43 commercial soybean products as well as on 3 gluten and 3 casein products. Principal component analysis was successfully applied for the classification of commercial products by their chemical constituents and protein properties. High correlation was observed between chemical composition and industrial processing method of soybean products. Correlation between water dispersible nitrogen and amount of native protein was unexpectedly low so that both should be taken independently as the indices for the discussion of functional properties.Flavor profiles of commercial soybean products were studied organoleptically and results were analyzed by using principal component analysis. Flavor of soybean products could be represented by two mutually independent characteristics. They are the so-called “Soybean Flavor” and “O...

Relation between Lipid Content of Milled Rice and Deterioration of Rice Flavors during Storage:Studies on Cereals (Part 7)

n-ヘキサン処理の条件を変え脂質含量の異なる精白米を調製した。肪質含量と米飯食味との間に一定の傾向は認められない。しかし脂質含量が少ないほど貯蔵中の品質劣化が少ないことを官能検査およびテクスチュロメーターの測定により明らかにした。