PURPOSE: To prepare a raw material for the preparation of malt, having high proliferation efficiency of yiest, conversion of saccharides, and productivity of alcohol, by mixing coarse particles of carbohydrate having high degree of α-conversion, and fine particles of carbohydrate having low degree of α-conversion.

CONSTITUTION: Raw material of carbohydrate, such as wheat, rice, corn, etc., is treated under high temperature and pressure to attain the degree of α-conversion of ≥ 85% using an expanding extruder, etc. and crushed to 8W30 mesh particles. On the other hand, the carbohydrate is treated with a pelleting machine to obtain pellets having a degree of α-conversion of ≤ 50%, pref. 20W50%, and crushed to particles having size of ≥ 16 mesh. pref. ≥ 30 mesh. The coarse carbohydrate particles having high degree of α-conversion and the fine carbohydrate particles having low degree of α-conversion, are mixed together in a ratio of 7:3 to 3:7.