Elimination of resistant starch type II within the framework of total starch and dietary fibre analysis by microwave irradiation

Abstract

Introduction The presence of resistant starch in samples containing non-starch polysaccharides has always been a challenge to enzymatic total starch and total fibre analysis. Objective and methods Based on microwave-induced pressure disintegration technique the Association of Official Analytical Chemists methods for the determination of total starch (AOAC 996.11) and total dietary fibre (AOAC 991.43) have been modified to completely eliminate undesirable resistant starch fractions with respect to digestion procedures using thermostable α-amylase and amyloglucosidase. Results Microwave treatment of high-amylose starch samples resulted in excellent total starch recovery in the Association of Official Analytical Chemists standard method no. 996.11. After integration of microwave disintegration technique into the total dietary fibre method AOAC 911.43 irradiation experiments with different model mixtures consisting of non-starch polysaccharides components and high-amylose starch fractions resulted in the complete elimination of undesirable resistant starch fractions. Conclusion Therefore the microwave technique can be a very efficient means for the elimination of resistant starch and provides more realistic values in analytical total dietary fibre procedures with respect to samples containing critical enzyme resistant starches.