Structure and digestibility of crystalline short-chain amylose from debranched waxy wheat, waxy maize, and waxy potato starches

Abstract

The structure and digestibility of crystalline short-chain amylose (CSCA) from debranched waxy wheat, waxy maize, and waxy potato starches were investigated and compared. The starches (5%, w/w) were cooked in acetate buffer (pH 4.0) and debranched by isoamylase at 50 °C. After 24 h, the mixture was cooled and held at 25 °C for another 24 h. Debranched waxy potato starch had a longer average chain length than debranched waxy wheat and waxy maize starches, resulting in a higher yield of crystallized product. All CSCA products displayed a B-type X-ray diffraction pattern, indicating that low solids concentration (5%) favored the formation of B-type crystals. CSCA from debranched waxy potato starch had a higher peak melting temperature (116.2 °C) and higher resistant starch content (77.8%) than that from debranched waxy wheat and waxy maize starches, suggesting that waxy potato starch is a preferred starting material to prepare products with high resistant starch content by debranching and crystallization.