Effect of acid-ethanol treatment and debranching on the structural characteristics and digestible properties of maize starches with different amylose contents

In this study, maize starches with different amylose contents were modified by acid-ethanol treatment (AET) to various degrees, followed by debranching and then recrystallization through temperature cycling to produce resistant starch type III (RS3). The structural characteristics and digestible properties of the AET-debranched starches were investigated. The result indicated significant reductions in amylose and long side-chain length in high-amylose maize starch (HMS) and normal maize starch (NMS), but minor variations in the chain-length distribution in waxy maize starch (WMS). All three maize starches exhibited increased relative crystallinities and RS levels following moderate AET; however, the increment varied according to starch types. The highest RS contents of HMS, NMS, and WMS at 66.8%, 58.7%, and 68.4% were obtained after 8 h, 24 h, and 14 h of AET, respectively. These results indicated that the appropriate reduction in chain length following AET and prior to debranching was beneficial to RS3 formation. (C) 2017 Elsevier Ltd. All rights reserved.