关键词: 支链淀粉, 结构, 糊化特征, 米饭质地, 水稻

Abstract: 【Objective】The objective of this paper is to explore the relationship between the physicochemical properties of amylopectin and pasting character of rice-flour. 【Method】Eight amylopectins from different rice varieties were used as materials, and the physicochemical properties such as blue value (BV) indicating iodine binding capacity and maximum absorption (λmax) and the chromatogram of debranched amylopection were analyzed by Sephadex G75.【Result】The results showed that the differences of BV and λmax.Ap of amylopectin among all cultivars were significant. BV and λmax.Ap of amylopectins from indica varieties were higher than that from Japonica varieties except Baxiluodao. A positive correlation (r=0.995**) between BV and λmax.Ap (except waxy cultivars) was observed. The average chain length of FrⅠ, FrⅡand FrⅢ separated by Sephadex G75 was greater than 100 glucose unite, 44-47 glucose unite and 10-17 glucose unite, respectively. The weight percentage of chain length distribution varied with typically different cultivars. Indica waxy cultivar contained more long chains than Japonica waxy cultivar, Indica cultivar consisted of more long branched chains than Japonica cultivars except Baxiluodao, and amylopectin from hybrid combination had more long chains than that from conventional cultivar. There was a positive correlation between the proportion of short chain FrⅢ and characters of RVA profile such as peak viscosity and breakdown (r=0.969**, r=0.949**). Correspondingly, the negative correlation of the proportion of long chain Fr (Ⅰ+Ⅱ) with peak viscosity and breakdown was discovered (r=-0.969**, r=-0.949**). 【Conclusion】The results suggest that the chain length distribution of debranched amylopection has a relation to rice quality. The higher ratio of Fr(Ⅰ+Ⅱ) in amylopectins from the non-waxy varieties, the more long branched chain, the texture of which shows that hardness and cohesiveness are high, and that looseness and adhesiveness are low, the taste sensory is delicious.

Key words: amylopectin, structure, pasting properties, cooked-rice texture, rice