Sachiko Furukawa

Distribution of storage proteins in low-glutelin rice seed determined using a fluorescent antibody.

To compare the distribution of storage proteins in low-glutelin rice seed with that in other cultivars having normal protein compositions, immunofluorescence labeling with specific antibodies was applied to visualize the distribution of storage proteins in endosperm tissues. The endosperm tissues from five cultivars were reacted with anti-prolamin and anti-glutelin antibodies, and then observed by light microscopy and confocal laser scanning microscopy (CLSM). In low-glutelin rice, using microscopic analysis, a large proportion of storage proteins was observed in the endosperm tissue of 70% polished rice. To determine the localization of two types of protein bodies in endosperm tissues, images of the distribution of the type I protein body (PB-I) and the type II protein body (PB-II) were obtained by CLSM. The CLSM images showed that, in low-glutelin rice, prolamin which accumulates in PB-I remains in the center of 70% polished rice grains despite the elimination of 30% of the outer layer of brown rice grains. However, the other cultivars mostly contained glutelin which accumulates in PB-II and is distributed throughout the endosperm tissues. This shows that low-glutelin rice differs from the other cultivars not only in the major storage protein composition but also in the distribution of storage proteins in endosperm tissues.

Influence of rice proteins on eating quality of cooked rice and on aroma and flavor of sake

ABSTRACT An 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 e...