剥蚀碾磨对陈米食用品质的影响

Effects of abrasive milling on eating quality of aged rice

为揭示陈米食用品质劣变的原因,通过剥蚀碾磨除去米粒外层,考察质构、糊化黏度、粒度分布及扫描电镜形态的变化,研究碾磨对陈米食用品质的影响。结果表明,随着碾磨度增大,蛋白质含量降低,陈米米饭黏度增大,硬度降低,糊化曲线回升值下降,食用品质得到改善;陈米米粒和外层米粉糊化后粒度分布的大粒径峰占比随碾磨度的增大而逐渐增加,表明米粉颗粒的溶胀程度增大,且呈整体溶胀。碾磨度在0%~5%的陈米粒外层糊化曲线黏度各特征值随碾磨度增大而增加,但碾磨度在5%~25%的米粒外层糊化黏度特征值总体变化不显著,说明越是米粒外层其糊化黏度越低;扫描电镜表明碾磨度在0%~5%的陈米粒外层淀粉颗粒和蛋白体溶胀程度低,而碾磨度在5%~25%的米粒外层溶胀的淀粉颗粒和蛋白体很少,说明陈米外层本身溶胀程度低,透水性差,可能是陈米品质劣变的重要原因。该研究结果将为阐明稻米陈化机理及调控米制品原料提供实验依据。

In order to reveal the cause of the deterioration of eating quality of aged rice,the outer layer of rice grains was removed by abrasive milling,and the changes in texture,RVA gelatinization viscosity,particle size distribution and scanning electron microscopy(SEM)were investigated.The results showed that as the degree of milling increased,the protein content,the hardness and the RVA setback decreased,the stickness of the cooked rice increased,thus the eating quality of aged rice were improved.The peak of large particle size increased for gelatinized aged rice with the increase of degree of milling,which indicated that the swelling degree of rice flour particles increased,and swelled as a whole.Furthermore,the RVA viscosity of the 0%-5%outer layer of aged rice grains increased with the increase of degree of milling.However,the viscosity of the 5%-25%outer layer did not change significantly,which indicated that the more outer layer,the lower gelatinization viscosity.Moreover,the SEM showed that the degree of swelling of starch granules and protein bodies in the 0%-5%outer layer of aged rice grain was low.But there was no significant change in the 5%-25%outer layer,indicating that the outer layer of aged rice itself had a lower degree of swelling and poor water permeability,which may be the reason for the eating quality deterioration of aged rice.This study provides an experimental basis for clarifying the aging mechanism of rice and regulating the raw materials of rice products.