Hardness and digestibility of steamed rice for sake brewing

Abstract

Measurement of the hardness of steamed rice is possible using a TENSIPRESSER. From thehardness measurement of 25% compression, we were able to measure the surface hardness of steamedrice and changes in the degree of hardening by cooling time. We confirmed that we could measure thehardness of every kind of steamed rice from the hardness measurement of 90% compression.
We expressed the ratio of the hardness by low compression and high compression with the degreeof kounan. As for Gohyakumangoku, the speed of surface hardening was fast, and we confirmeda behavior unlike other kinds. In addition, the degree of kounan of Sensyuraku showed a value that wasnear those of Koshitanrei and Takanenishiki. Regardless of cooling time, it was close to the kind of Kounan that was hard to stiffen due to its change to uniformity.
We was confirmed that prolamin had a close correlation to the hardness of steamed rice after onehour of cooling. This correlated with an interesting result from recent sake brewers producing sake bycooling machines in a short time. However, no meaningful result was obtained by a cooling time of 3, 6 hours. It is believed that the factor which affected aging was not prolamin.