The degree of paddy cracking during HTS was evaluated using the model shown in Fig. 1. The percentage of partially or fully exposed endosperm or starch (H þ W, %) out of the total paddy grains was calculated to assess the relationship between the HTS time and paddy cracking (that is, the release of the albumen from the rice husk) because the degree of paddy cracking is thought to be important for the enzymatic reactions with albumen. The starch value was measured according to a previously described method , and the mutarotase GOD method was used to measure the reducing sugar produced by the acid degradation of starch. The amounts of total sugar, glucose and ethanol were estimated by the phenol-sulfuric acid method , mutarotase GOD method and gas chromatography , respectively.