Cassava starch granules were treated with three types of amylase and the resulting insoluble starch granules collected and their gelling properties investigated. Gel produced from starch granules treated with either α-amylase from Bacillus amyloliquefaciens or β-amylase from barley was slightly weaker than that from native cassava starch granules. On the other hand, starch granules treated with α-amylase from Aspergillus niger produced starch gel with significantly enhanced hardness and elasticity. This observation is surprising because very limited hydrolysis (2.8%) of starch produces such a great impact on gelling properties of starch and because it contradicts the generally held view that partially hydrolyzed starch shows decreased gel-forming ability. In order to understand the mechanism behind this, we analyzed the starch component leached from starch granules into hot water using gel permeation chromatography. The results suggest that enzymatic treatment of starch granules significantly changes the properties of starch by altering the composition of leached material (matrix) from swelled starch granules (filler).
2014 by The Japanese Society of Applied Glycoscience