Changes in the firmness of peach tissues, the amounts of water-soluble pectin and water-soluble polysaccharides, and the polygalaturonase activities of peach fruit were investigated from days 70 to 130 after the ‘Hakuto’ peach tree had blossomed. The firmness of the fruit tissues decreased linearly during maturation, and the mouthfeel rapidly became soft at the fully ripe stage. The polygalacturonase activities increased rapidly, and then pectin and polysaccharides were rapidly solubilized by the time of full maturation. Observation with a cryo-scanning electron microscope showed that, while the unripe cell wall was substantial, small round holes were widely distributed in the cell wall by the 108^th day after blossoming. The firmness of the tissues on the 108^th day was about half that on the 77^th day. By the 126^th day (the full ripe stage), the middle lamella had split and the separation of the primary cell walls had widened. These findings suggest that the histological changes during maturation might depend on the solubilization of pectin and polysaccharides.

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Three varieties of glutinous rice harvested in Nagano in 2006 as new rice and harvested in 2005 as old rice were used as samples. The palatability of mochi cooked from the rice samples was evaluated. The association of the gelatinization characteristics, hardness of the mochi dough and degree of extension, with the physicochemical properties and flavor analysis was studied. The correlation between the palatability and physicochemical properties was also evaluated. Peak viscosity of gelatinization property and flavor value (SC 1) negatively related to five items (extension, texture, taste, aroma, general evaluation). The effect of the degree of extension on the mochi dough property was large as a regular factor. The harvest year for each variety. differentiated the score by the principal component analysis into two groups. The factor analysis indicated that the degree of extension, texture and the variable effect of setback were negative factors determining old rice according to the period of storage.

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The gelation characteristics of a gelatin sol containing various concentrations of rutin were studied as a basic experiment to produce gelatinous buckwheat food. The sol-gel transition temperature of gelatin was hardly changed by adding rutin as measured by both a hot-wire method and by dynamic rheometry. The storage modulus of the gelatin gel was markedly increased when containing over 1,000 ppm of rutin. No cross-link formation of the gelatin molecules with rutin addition was apparent from a molecular weight distribution analysis by HPLC. The recrystallization of added rutin was observed at around this concentration The rupture stress of the gel was correspondingly increased, and the rupture strain of the gel was decreased with increasing rutin content. We consider that this recrystallization caused the change in rheological properties of the gel. We propose gelatinous buckwheat as an appropriate food in view of its favorable texture, and conclude that common buckwheat flour and a buckwheat tea infusion would be suitable because of their rutin content.

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The presence of acrylamide(AAm) was evaluated in vegetables cooked at home by heating. The AAm content was highest in bean sprouts and second highest in garlic. A close correlation was apparent between the asparagine (Asn) content and the post-heating AAm content in the vegetables tested(R²=0.66). It was also found that the AAm content could vary greatly depending on the heating conditions, even when the Asn content was low. The results suggest that acrylamide formation can be suppressed by avoiding excessive heating when cooking vegetables at home.

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