精白保胚米发芽过程中淀粉酶及相关营养成分的变化

Changes in Amylase and Nutrients in Polished Rice with Intact Germ during Germination

研究精白保胚米发芽过程中α-淀粉酶、β-淀粉酶和葡聚糖内切酶活力的变化,同时测定其中还原糖、总糖、淀粉及热水溶性直链淀粉的含量变化,并以发芽糙米作为对照。结果表明:精白保胚米和糙米发芽过程中α-淀粉酶和β-淀粉酶的活性先由低变高,再由高变低,精白保胚米在发芽16h时淀粉酶的活性最高,而糙米在发芽时淀粉酶活性达到最高点时间较长;葡聚糖内切酶活力随发芽时间的增加活性逐渐升高,糙米在发芽过程中葡聚糖内切酶活力高于精白保胚米。还原糖、总糖的含量随着时间的增加而升高,在20～24h后逐渐降低,精白保胚米在发芽过程中还原糖的含量高于糙米。淀粉含量随发芽时间的延长而逐渐降低,热水溶性直链淀粉的含量则不断增加。

Changes in amylase and nutrients of polished rice with intact germ and brown rice during germination were investigated. The results showed that the activities of α-amylase and β-amylase revealed an initial increase and a final decrease during germination. The a-amylase activity of polished rice with intact germ reached up to the highest level after germination for 16 h, which was shorter than that of brown rice. The activity of endoglucanase in polished rice with intact germ also revealed an increase during germination, which needs the shorter time for reaching the same level than that of brown rice. Similarly, the contents of total sugar and reducing sugar revealed an initial increase and a final decrease during germination. However, the content of reducing sugar in polished rice with intact germ was higher than that of brown rice. The content of starch exhibited a decrease during germination, while amylose had the increasing hot-water solubility during germination.