Reducing digestibility and viscoelasticity of oat starch after hydrolysis by pullulanase from Bacillus acidopullulyticus

It is highly desirable to change the physiochemical properties of oat starch for different food applications. In this study, oat starch was hydrolysed by Bacillus acidopullulyticus pullulanase (PUL). The content of slowly digestible starch and resistant starch in PUL-modified oat starch increased significantly, from 62.5% to 74.6% (P < 0.05), when 120 U/g starch of PUL was used in the debranching reaction. A PULmodified oat starch paste had significantly decreased viscoelasticity (P < 0.05) but still exhibited pseudoplasticity. The molecular weight, amylopectin B3 chain, and amylopectin B2 chain of PULmodified starch were lower, whereas the amylose content, amylopectin B1 chain, and amylopectin A chain were higher than those of natural oat starch. These changes in molecular structure partially explain the reduced digestibility and viscoelasticity. (C) 2017 Elsevier Ltd. All rights reserved.