Effect of Addition of Acid on the palatability and the Staling of Cooked Rice

研究了醋酸水溶液蒸煮对大米理化性质的影响。用0、0.05、0.1和0.2M乙酸水溶液蒸煮日本粳稻。用质构仪测定，醋酸蒸煮的米饭比水蒸煮的米饭硬度低，粘性高。这些效果通过感官评价得到证实。在烹饪过程中增加的葡萄糖量是更高的米饭与醋酸煮比米饭与水煮。还原糖和总游离氨基酸大米也较高的米饭与醋酸煮比不加酸煮。这些试验是在其他品种的玫瑰上进行的。以泰国的长粒米、滋贺县的日本晴、新泻县的越光和佐贺县的日久持为研究对象。醋酸蒸煮的效果因大米品种不同而有明显差异。 ...更多信息 用醋酸水溶液蒸煮的泰国米，其抗折强度急剧下降，而粘附强度增加，粘附应变几乎没有变化。另一方面，日久持的断裂强度和粘附强度没有随着乙酸的添加而改变，而粘附应变显示出明显的增加。用乙酸烹饪对日本晴和越光的质地的结果介于泰国米和日久持的结果之间。最后，测量了在烹饪前浸泡大米时溶解到水中的蛋白质的量，因为据说大米颗粒中的蛋白质可以防止淀粉的膨胀。蛋白质溶于含乙酸的水中比溶于不含酸的水中的蛋白质多。特别是溶于含醋酸水的醇溶谷蛋白和谷蛋白含量高于溶于不含醋酸水的含量。从这些结果中可以看出，用乙酸烹饪的米饭质地改善的原因之一是蛋白质的溶解。少

The effect of cooking with acetic acid aqueous solution on the chemical and physical properties of rice was examined. Japonica rice, Nipponnbare, was cooked with 0, 0.05, 0.1 and 0.2M aqueous solutions of acetic acid. The rice cooked with acetic acid showed lower hardness and higher stickiness than the rice cooked with water when measured by texturometry. These effects were confirmed by a sensory evaluation. The increased amount of glucose during cooking was higher for the rice cooked with acetic acid than for the rice cooked with water. Reducing sugars and total free amino acids rice were also higher for the rice cooked with acetic acid than for the rice cooked without acid. These tests were conducted on other varieties of rise. Long grain rice from Thailand, Nipponnbare from Shiga-Prefecture, Koshihikari from Niigata-Prefecture and Hiyokumochi from Saga-Prefecture were chosen as samples. The effect of cooking with acetic acid was obviously different according to the variety of rice. … More The breaking strength of the Thai-rice cooked with acetic acid aqueous solution decreased drastically, while the sticking strength increased, the sticking strain hardly changed. On the other hand, the breaking strength and the sticking strength for Hiyokumochi did not change with the addition of acetic acid, while the sticking strain showed obvious increase. The results of cooking with acetic acid on the texture of Nipponnbare and Koshihikari were somewhere between the results for Thai-rice and Hiyokumochi. Finally, the amount of protein that had dissolved into the water when the rice was soaked prior to cooking was measured, since the protein in rice granules is said to prevent the swelling of the starch within. More protein had dissolved into the water containing acetic acid than to the water containing no acid. Especially, prolamine-rich-fraction and glutelin-rich-fraction that dissolved into the water containing acetic acid were higher than the amount that dissolved into the water containing no acid. It is suggested from these results that one of the reasons for the improved texture of rice cooked with acetic acid derives from the solubilization of the protein by this. Less