New rice; old rice

Generally speaking, the rice from the new harvest in autumn is called “new rice” (新米, shinmai) to distinguish it from that from the preceding harvest, “old rice” (古米, komai). In an average year, new rice comes on the market around September. In administrative terms, the Rice Year (Beikoku Nendo) changes on November 1st, so all the rice produced before then is “old rice”, and all produced afterwards after is considered new rice.

Under natural conditions, the vitality of the germ and the capacity to germinate deteriorate in old rice, and enzyme activity in the grain causes a decline in quality. Although the degree of change varies with the water content of the stored rice and storage temperature, fats decompose and inorganic substances such as potassium shift into the inner part of the grain. Sake made using rice which has been fumigated and stored for a long period may have the characteristic “old rice smell” (komai-shu (long “u”)).