Studies on optimum harvesting time of rice grains for good eating quality of cooked rice

为了明确米粒最佳收割时间对米饭食用品质的影响，特别是“甜”、“香”的口感，比较了早稻在普通最佳收获期前10天(抽穗后40天)与普通稻米在普通最佳收获期收获的稻米品质。从感官测试结果来看，早熟大米比普通大米更甜、更美味、整体判断更好。早熟大米的甜度较高，主要是因为在浸泡和/或烹饪过程中，淀粉可能通过淀粉降解酶形成葡萄糖、麦芽糖和麦芽低聚糖，如麦芽三糖和麦芽四糖。早熟大米中L-谷氨酸的含量高于普通大米。结果表明，在常规最佳收获期前10天(抽穗后40天)收获米饭时，米饭更加甜美可口。

In order to clarify the optimum harvesting time of rice grains for the good eating quality of cooked rice, especially on the taste items of "sweetness" and "deliciousness, " I compared of early-harvest rice which was harvested at 10 days before the ordinary optimum time of harvesting (40 days after heading) and ordinary-harvest rice, which was harvested at the ordinary optimum time. From the results of sensory tests, the cooked early-harvest rice was evaluated as being sweeter, more delicious and better overall judgment than the cooked ordinary-harvest rice. The greater sweetness in the cooked early-harvest rice was primarily due to the formation of glucose, maltose and maltoligosaccharides, such as malttriose and malttetraose, from starch probably by starch degradation enzymes during soaking and/or cooking. The cooked early-harvest rice contained more L-glutamic acid than the cooked ordinary-harvest rice. From these results, it was concluded that when rice is harvested 10 days before the ordinary optimum time of harvesting (40 days after heading), the cooked rice would be sweeter and more delicious.