Resistant rice starch development

Abstract

This study showed that enzyme treatments were effective in producing resistant starch from rice flour and starch. Rice starch produced higher resistant starch yields than rice flour. The lower resistant starch yields in rice flour could be attributed to the presence of lipids and proteins which were competitively binding to amylose, resulting in decreased recrystallization of amylose. The gelatinization type and incubation periods were not as influential as enzyme treatments in the resistant starch formation. The rapid visco amylograph (RVA) analysis indicated that the gelatinized samples have minimal pasting characteristics since they had been gelatinized prior to enzyme treatments. Pasting viscosity was decreased in the non-gelatinized samples if they had been treated with ¥á-amylase-pullulanase or ¥á-amylase. The higher incubation temperatures in conjunction with the random cleaving effect of ¥á-amylase could have caused the reduced pasting characteristics. The rice flour and starch pasting characteristics were similar. Several of the gelatinized rice flour and starch samples underwent gelatinization during analysis with differential scanning calorimetry (DSC). Three of the non-gelatinized rice flour samples, NGNS (non-gelatinized, no overnight storage) 2hr and 4hr (¥á-amylase) and NGNS16hr (¥á-amylase-pullulanase) did not have gelatinization peaks. Amylose-lipid complexes and resistant starch were detected in most of the treated samples. Reheating of the samples with resistant starch peaks showed that some of the samples had heat stable resistant starch.