Abstract
To presume maximum viscosity (MV) obtained by amylography a method based on alpha- amylase activity was developed. Alpha-amylase activity was assayed using blocked p-nitro- phenylmaltoheptaoside as a substrate (CERALPHA METHOD, Megazyme Pty. Ltd., Australia). MV and alpha-amylase activity were determined in various flours prepared by mixing flours obtained from germinated and ungerminated wheats at various ratios. Loge MV decreased linearly with increasing of loge alpha-amylase activity. Regression lines of 4 varieties and one brand of wheat flours were different from each other, but the differences were very small in the low MV region which corresponds to wheat sprouted to some extent. Therefore, we made a tentative criterion to presume MV, that is, sprout damaged wheat, by alpha-amylase activity. Group 1: Wheat with alpha-amylase activity below 70mU/g flour; wheat must be undamaged. Group 2: Wheat with alpha-amylase activity 70mU to 100mU/g flour; wheat may be sprout damaged. Group 3: Wheat with alpha-amylase activity above 100mU/g flour; wheat must be sprout damaged. In order to examine adaptation of the criterion, 29 wheat samples which sprouted or unsprouted in fields were analyzed. The result indicated that the criterion may be available to judge sprouted wheats. With CERALPHA METHOD, almost 60 samples are analyzed in a day. Therefore sprout damaged wheats can be classified rapidly compared with amylography method.
