选用11个水稻品种，通过二硫苏糖醇（dithiothreitol，DTT）处理打破蛋白质二硫键后，观察稻米粉快速黏度仪RVA（Rapid Visco Analyzer）特征谱的形成、特征值及其米饭质地的变化，进而研究蛋白质对米饭食味品质的作用。结果表明，供试品种米粉添加DTT后，其RVA的峰值黏度和糊化温度大都显著或极显著下降，崩解值大都显著或极显著上升，RVA特征谱上升阶段的线性部分的斜率大都减少；米饭质地则大都变软变黏。稻米中由二硫键形成的蛋白质网络可能增强糊化液的刚性或蛋白质水合作用而改变淀粉的吸水性能，两者共同作用协同提高RVA的峰值黏度和糊化温度等。由二硫键结合而形成的蛋白质网络也可能是影响米饭硬度和黏性的主要作用之一。
11 rice cultivars with different amylose contents were chosen to determine the impact of protein on forming a viscosity curve when treated with reduced reagent dithiothreitol (DTT) to disrupt the protein disulphide bonds, and then to understand how protein affect the eating quality of cooked rice. DTT decreased RVA pasting temperatures and peak viscosities of flours with different degrees in all cultivars, while increased breakdown viscosities in 5 cultivars. DTT also changed the slopes of the linear parts of the curves for each variety. The addition of DTT to the cooking water decreased the hardness, while increased the adhesiveness of cooked rice. The disulfide bond-containing protein had a substantial impact on the pasting and cooking properties of rice. RVA measurements indicated that in addition to the disulphide bond network, protein hydration based increase of the gelatinized paste concentration contributed to the enhancements of the paste rigidity during cooking. The role of disulphide bonds in augmenting the breakdown viscosity values indicated that in the absence of the rigidity conferred by the disulfide-bound protein, swollen starch granules broke apart more easily when shear stress was high. From these observations, it was anticipated that disulfide bond-containing protein agency also played a role in the texture of cooked rice; this was confirmed by cooking rice in the presence of DTT. The agency of protein network increased hardness and decreased the stickiness of the cooked rice. Furthermore, the observation that the effects of DTT on high-amylose rice texture properties were slight suggested that, apart from an agency of protein network, a strengthening of an amylose barrier present in the rice endosperm seemed equally or more important.
全 文 ：