Influence of amylases on the rheological and molecular properties of partially damaged wheat starch

Abstract The effects of Bacillus subtilis, porcine pancreatic and Aspergillus oryzae α‐amylases, sweet potato β‐amylase and Bacillus stearothermophilus maltogenic amylase (BStA) on the rheological properties (measured with a Rapid Visco Analyser) of partially damaged wheat starch were studied and the accompanying changes in starch molecular properties were analysed by high‐performance size exclusion chromatography. Pasting and gelation of starch slurries (with an increased level of damaged starch) were significantly affected by the supplemented amylases and greatly depended on the mode of action and properties of the enzymes added. In general, at low endo‐amylase concentrations, peak, hot paste and cold paste viscosities were more reduced for enzyme‐supplemented partially damaged starch than for enzyme‐supplemented native wheat starch, demonstrating the significance of damaged starch levels in determining amylase functionality. Higher dosages of thermostable amylases ruled out most of the differences between amylase‐supplemented native starch and partially damaged starches, except for BStA. Furthermore, the (limited) endo‐action of BStA determines to a great extent the rheological properties of the starch paste. These results contribute to a better understanding of (maltogenic) amylase functionality in processing (damaged) starch‐containing foods. Copyright © 2006 Society of Chemical Industry