脉冲微波处理对大米理化指标和流变特性的影响
Effects of pulsed microwave on physicochemical and rheological properties of rice

采用脉冲微波处理大米，以普通连续微波作对照，考察脉冲微波处理对大米理化指标和流变特性的影响，并对蒸煮后的米饭感官品质进行评价。结果表明：大米经过微波处理后其温度、碎米率、爆腰率和碘蓝值均高于未处理，含水量低于未处理，脉冲微波处理后的大米的爆腰率（10%）显著低于普通连续微波处理（24%），更接近于未处理（8.5%）。稳态剪切模式下，未处理和微波处理后的大米糊均属于典型的非牛顿流体，呈现假塑性流体的特征，经脉冲微波和普通连续微波处理后，大米糊的黏稠性降低，流动性增强，更接近牛顿流体。动态振荡模式下，未处理和微波处理后的大米糊化温度均在68℃左右，经脉冲微波和普通连续微波处理后的大米糊G′和G″峰值均高于未处理的大米糊，表明微波处理能增强大米糊的三维凝胶网络结构。脉冲微波处理对蒸煮后米饭的感官品质无显著性影响，且在形态得分上优于普通连续微波处理。
The effects of pulsed microwave on physicochemical,rheological properties and sensory quality of rice were studied using ordinary continuous microwave as control.The results showed that the temperature,broken rice rate,percent cracked rice and blue value of microwave treated rice were higher than that of untreated rice,except for the moisture content.The percent cracked rice after pulsed microwave treament (10%) was significantly lower than that of ordinary continuous microwave (24%),close to untreated rice (8.5%),indicating that the effect of pulsed microwave was better than that of ordinary continuous microwave.In steady shear mode,all rice pastes were typical non Newtonian fluid with pseudoplastic behavior.Compared with untreated rice paste,the viscosity of rice paste treated with microwave decreased and the mobility increased,close to a Newtonian fluid.In dynamic oscillation mode,the pasting temperature of both untreated and microwave treated rice were at ~68℃.The storage modulus (G′) and loss modulus (G″) of microwave treated rice paste was higher than that of the untreated rice paste,indicating that the three dimensional gel network in the rice paste could be enhanced by microwave.There was no significant changes in the sensory qualities of rice treated by pulsed microwave.The shape score of cooked rice treated by pulsed microwave was significantly higher than that of ordinary continuous microwave.The pulsed microwave will have a potential application in the processing and storage of food.