稻谷储存过程中品质变化研究

Quality Change of Paddy during Storage in Controlled Environment

通过对3个籼稻和3个粳稻在两种不同温度条件下储存的品质变化研究,探索稻谷储存品质产生的内在原因。结果表明:不同类型的稻谷在储存过程中的品质变化不同,与籼稻相比,粳稻部分指标对高温更加敏感;高温储藏比低温储藏导致稻谷品质劣变的速率大;稻谷糊化特性发生明显的变化,主要表现为峰值黏度,最低黏度,最终黏度和回生值都增大,而衰减值下降;利用物性仪对大米蒸煮后的质构特性测定表明,蒸煮米饭黏度减小、硬度增大、黏/硬减小;蒸煮品尝值与最低黏度、最终黏度极显著负相关,初步认为其可以作为初始判定稻谷陈化指标,但是对稻谷劣变程度的量化还需要进一步深入研究;利用SEM研究稻谷籽粒断面结构,显示:新鲜稻谷的胚乳细胞呈现非裸露状态,比较平滑,复粒淀粉被较厚的造体膜掩盖着,高温储藏下,稻谷横断面越来越粗糙,配入细胞内的淀粉粒裸露清晰可见,复粒淀粉的淀粉粒表面膜翘起并爆开。

The quality deterioration of stored paddy was studied with six paddy samples,three of which were round grain rice and the others were long grain rice.Results： Paddy quality changes differently according to rice category;the round grain rice samples are less bearable to high temperature comparing with the long grain rice samples.The rate of rice deterioration at high temperature is more rapid than that at low temperature.The pasting characteristics change obviously during storage;peak viscosity,holding viscosity, final viscosity and setback increase while breakdown decreases. The textural tests for cooked rice illustrate that the stickiness of cooked rice decreases and the hardness increases during storage. The sensory score of cooked rice has a significant negative correlation with the holding viscosity and final viscosity, which might be the potential factors to predict the beginning of paddy deterioration. Further study should be carried out to determine the viscosity values. The microstructure difference between fresh and aged paddy kernels was also investigated, providing a new way to study paddy deterioration.