Resistant starch content, pasting properties, and morphology of taro (Colocasia esculenta L. Schott) flour modified by heat-moisture treatment

Abstract

Taro flour was modified by heat-moisture treatment (HMT) in various times and aimed to evaluate its resistant starch content, pasting properties, and morphology. The moisture content of taro flour was adjusted into 25% before heating at 110°C for 4, 6 and 8 h to produce modified flour. HMT of 8 h and 6 h exhibited the similar amount of resistant starch compared to native flour, while HMT of 4 h resulted in significantly lower RS content. The modification process increased all of pasting parameters: peak, trough, breakdown, final viscosity, setback, peak time, and pasting temperature. No sign of fractures were exhibited on the surface of native taro flour granules visualized in SEM micrograph. While modified taro flour resulted in some cracks which might be due to partially gelatinized around the surface by heat and moisture treatment.