Structure and digestibility of debranched and hydrothermally treated water yam starch

Debranched water yam starch was subjected to repeated hydrothermal treatment (HTT), and its physicochemical and structural properties and digestion pattern were investigated. The B-type crystalline pattern of raw starch was recrystallized to B- and CA-type patterns by debranching and repeated HTT. The degree of relative crystallinity of debranched starch gradually increased and reached its maximum (43.3%) after five repetitions of HTT. The thermal transition temperatures and melting enthalpy of recrystallized starches increased progressively, reflecting the perfection of their crystalline structure, leading to the accumulation of boiling-stable crystalline structure under repeated HTT conditions. As a result, RS of HTT starches reached a very high level (>92.2%). The boiling-stable RS content depended on the repetition of this treatment and was maximized (81.0%) after five repetitions.