Screening of α-Amylase Suitable for Evaluating the Degree of Starch Retrogradation

To estimate the degrees of starch retrogradation in the complex foods, an enzymatic method using α-amylase from Bacillus subtilis was proposed in the previous report (Tsuge, H. et al.: Starch/Stärke 42 (1990), 213–216). However, actual digestibility of the enzyme for the native starch granules was not checked at that time. A comparative study to see the digestibility of native starch granules was carried out using four different α-amylase preparations and digestion of retrograded wheat starch was tested by two α-amylase preparations. Pancreas α-amylase preparation digested some native starch granules to a great extent, while Aspergillus oryzae enzyme did not digest native starch granules virtually. In conclusion, α-amylase preparation from A. oryzae was an ideal enzyme as the tool to distinguish between raw and gelatinized starches. It was justified for the use of A. oryzae enzyme as well as B. subtilis α-amylase to evaluate the retrograded starch contents in the complex foods.