Grain Quality Characteristics and Structure of Opaque and Translucent Endosperm in Sang Yod Rice Variety

Abstract

“Sang Yod” is a red rice variety, good cooking quality, high nutrition and most popular among health-conscious consumers. Sang Yod has opaque and translucent endosperm of seeds occurring in the different proportion, both within and between population and the different growing area. The objective of this study was to evaluate grain quality characteristics and structure of opaque and translucent endosperm. Samples (22) of Sang Yod rice were collected from farmer’s fields and planted to evaluate the proportion of opaque and translucent endosperm using physical and chemical characteristics, and endosperm structure under the scanning electron microscope (SEM). Opaque seed was thicker than translucent endosperm (1.59 and 1.55 mm, respectively). The 100 seed weight of translucent endosperm (1.50 g) was significantly heavier opaque endosperm (1.43 g) (p < 0.01). There were no differences in fat (11.32-11.40 %) and amylose content (5.38-5.50 %). The starch granule arrangement of translucent grain was more compact than opaque grain, starch granule size of translucent seed (3.09-10.04 µm) was bigger than opaque seed (2.66-9.49 µm) and had higher internal cavity than opaque seed. Therefore, differentiation of opaque and transparent weight will affect the commercial quality. The starch granule arrangement and gaps in starch structure may be related to the cooking quality, which should be further studied.