Abstract
Digestion of boiled rice by various amylases was tested in vitro at pH 6.0 and 4.7, and at 37°. The results showed that the digestion was best related to the starch liquefying activity of the amylases among the three expressions of the amylase activity, i. e., saccharifying, dextrinizing, and liquefying. A. oryzae amylase was weak in the dextrinzing activity on amylopectin itself, and was weaker on that in starch, because it had more affinity to amylose than to amylopectin so that it was the weakest of all in the starch liquefying activity. A. oryzae amylase was adsorbed markedly on boiled rice at pH 4.7 and 37°, and it remained active as a saccharifying amylase losing its original liquefying character. Salivary amylase was weak in the dextrinizing activity on amylopectin itself, but it was strong in the starch liquefying activity because of its marked affinity to amylopectin in starch. B. subtilis amylase was strong in the starch liquefying activity as well as in the dextrinizing activity on amylopectin itself, and was characterized by its high reaction rate in early stage of amylopectin decomposition. The above dextrinizing activity of amylase on amylopectin itself was discussed on the . basis of its dextrinizing activity on amylose itself, and the starch liquefying activity and the dextrinizing activity on amylopectin in starch were discussed on the basis of its starch dextrinizing activity.
