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为明确大米辐照后黏度下降的原因,将粳米粒放在不同剂量的60Co-γ射线下辐照后观察了淀粉粒的形态与结构,测量了蒸煮黏度、碱溶蛋白分子量种类以及自由基含量的变化。结果表明,随辐照加强,粳米的蒸煮黏度的数值自213cPs单调降低到21cPs;淀粉组织崩解碎裂;蛋白质碎片增多,生成了35kD以下的小蛋白片段和肽;自由基增多,ESR信号增强;大米受γ射线辐照时,其成分物质中的电子从原有轨道激发电离,生成电子未配对的自由基,与淀粉、蛋白质等反应,导致后者断裂;以及辐射的生热效应使淀粉和其它成分膨胀产生的应力使大米结构崩解,也是粳米黏度降低的部分原因。
In order to clarify the reason of the viscosity decrease after irradiation, the morphology and structure of starch grains were observed after the rice grains were exposed to different doses of 60Co-γ rays. The viscosity, the molecular weight of kibbles and the content of free radicals The change. The results showed that with the increase of irradiation, the cooking viscosity of japonica rice decreased monotonically from 213 cPs to 21 cPs; the starch tissue disintegrated and fragmented; the number of protein fragments increased and the small protein fragments and peptides below 35 kD formed; the increase of free radicals and the enhancement of ESR signal When rice is irradiated by γ-ray, the electrons in its constituent substances are excited and ionized from the original orbit to generate electron unpaired free radicals, which react with starch, protein and the like, resulting in the latter being broken; and the heat-generating effect of radiation causes starch and The stress caused by the swelling of other ingredients disintegrates the rice structure, which is also partly responsible for the decrease of the viscosity of japonica rice.