高水分成品大米低温储存及低温解除后品质变化研究

Quality change of rice with high moisture content during low temperature storage and after removed from low temperature

通过对东北高水分粳米低温储存及解除低温后的试验研究,探索高水分大米低温储存品质变化规律.结果表明：大米初始水分为17.54％,在温度低于15℃、相对湿度60％～ 70％的条件下,储存10个月,大米水分维持在16.0％,脂肪酸值低于25 mgKOH/100 g,大米品质无明显劣变,在宜存范围内.储存过程中大米L值降低,b值升高,a值变化无明显规律.TPA质构分析显示,蒸煮米饭硬度增大,黏性、弹性下降,内聚性增加.储存6个月后,各项指标发生明显变化.低温解除后,在夏季,高水分大米储存1个月后发生霉变,水分、脂肪酸值、色差值均发生明显变化.扫描电镜观测结果表明：随储藏时间延长,米粒表面裂纹空隙增大,淀粉粒裸露,去胚部后形成空洞.胚乳细胞表面小孔增多变大,细胞表面被包裹的复合淀粉体之间的界限变得模糊,蛋白质膜明显翘起.

The quality change by the test with japonica rice of rice with high moisture content during store at low temperature was studied from northeast China. The results showed that the rice with the initial moisture content 17.54% would maintain moisture content of 16.0%, fatty acid value less than 25 mg KOH/ 100g when it was stored at below 15 ℃, relative humidity 60% -70% for 10 months, which had no obvious quality deterioration and was in the range of suitable storage. During the storage, L value was reduced, b value increased, a value had no obvious regularity. The analysis of TPA quality and structure for cooked rice showed that the hardness increased, the viscosity and elasticity descended, cohesion increased. After 6 months, the indicators changed obviously. In summer the rice with high moisture content stored for 1 mildewed after removed from low temperature. The moisture content, fatty acid value and color difference altered obviously. The result determined by scanning electron microscopy showed that along with the extension of storage time the crack on the surface of the rice kernel was enlarged, starch grains were exposed and embryo part formed hollow. The pores on the endosperm cell surface increased in size and number, the boundaries between the wrapped composite amyloid become blur and protein membrane obviously cocked.