Abstract: With Fengliangyou 1 sowed or harvested at different dates, the effects of sowing and harvest dates on rice amylose content, swelling power(SP), protein content,  RVA viscosities and eating quality were analyzed, respectively, as well as changes of RVA viscosity and swelling power after protein removal or disulphide bond disruption, and the factors related to rice eating quality.  Preincubation of all flours with dithiothreitol (DTT) or a protease increased SP. The amylose content, protein content, SP and RVA viscosity values were similar between sowing Ⅲ（13th June） and sowing Ⅳ(23th June), but the eating quality of rice for sowing Ⅲ was better.  When treated with trypsin, the slope of the linear region of each curve for both samples was similar, but the liftoff from hot viscosity to the cool viscosity part varied and the hot viscosity and cool viscosity of sowing Ⅲ were significantly lower than those of sowing Ⅳ. The latter part of the RVA paste rigidity was affected by the proportion of the quantity starch to water.  Paste rigidity decreased greatly and resulted low values, suggesting that the difference of water holding capacity of protein after protein hydration may  play a major role in determining the eating quality of cooked rice. 

Key words: RVA viscosity, eating quality, protein, rice, mechanism

摘要： 以杂交中籼丰两优1号组合为材料，设置不同的播期和收获期，分析稻米主要品质指标(直链淀粉、总蛋白含量、RVA特征值等)和米饭食味品质，并用二硫苏糖醇 (DTT)或蛋白酶(Trypsin)分别打破样品蛋白质二硫键或酶解蛋白质后，观察RVA特征谱和膨胀势的变化，旨在明确蛋白质对不同食味品质样品RVA的影响，进而探索蛋白质影响米饭食味品质的机理。结果表明，第3播期(6月13日)稻米品质主要指标（直链淀粉、总蛋白、膨胀势、RVA特征值）与第4播期（6月23日）样品差异不显著，但食味品质明显好于后者；分别经蛋白酶处理后，第3和第4播期样品RVA上升段斜率差异不显著，但前者后段冷却后回升斜率明显小于第4播期。由于影响RVA特征谱后段凝胶刚性的主要因素是淀粉与水之比，刚性随淀粉凝胶中含水量减少而提高，食味品质较好的第3播期米粉经蛋白酶处理后，凝胶刚性小且减弱程度大，这可能是蛋白质酶解后形成蛋白质碎片的持水能力弱，即淀粉与水之比低，由此推测蛋白质影响米饭食味品质可能在米饭蒸煮后阶段，即可能与蛋白质水合后持水能力差异有关。

关键词: RVA, 食味品质, 蛋白质, 水稻, 机理