Effect of controlled gelatinization in excess water on digestibility of waxy maize starch

An aqueous dispersion of waxy maize starch (5%, w/w) was controlled gelatinized by heating at various temperatures for 5 min. The treated samples were analysed using in vitro Englyst assay, light microscopy, differential scanning calorimetry, X-ray diffraction, and Fourier-transform infrared spectroscopy. When heated, SDS and RS levels were decreased inversely with RDS. A high SDS content (>40%) was kept prior to the visible morphological and structural changes (before 60 degrees C). Swelling factor began to increase slightly at 50-60 degrees C and continued to maximum value at 80 degrees C. A large decrease in Delta H, crystallinity, and ratio of 1047/1022 cm(-1) attributed to partially dissociation of crystalline clusters and double helices occurred at 65-80 degrees C. These changes showed that controlled gelatinized starch with slow digestion property occurred in the molecular rearrangement process before granule breakdown and SIDS mainly consists of amorphous regions and a small portion of less perfect crystallites. (C) 2009 Published by Elsevier Ltd.