Weighing 2g dry koji, then crushed by a Muller. The crushed sample (2g) was
extracted with (36-2×moisture%) ml water and 4ml buffer for 1h at 40℃ water bath, stirring once every 15min, then
filtering with a dry filter paper, discarding the first 5ml, receiving remain clear to use. Glucoamylase activity was
measured by using the method of GB 8276-2006 food additive provisions glucoamylase preparations.