Effect of heat moisture treatment and partial acid hydrolysis on the morphological, functional and pasting properties of sweet potato starch

Sweet potato starch was modified by partial acid hydrolysis (PAH) and heat-moisture treatments (HMT) at different moisture content and temperature (HMT1: 20% moisture, 90 °C; HMT2: 20% moisture, 110 °C; HMT3: 30% moisture, 90 °C temperature; HMT4: 30% moisture, 110 °C). Modification was also done by combination of HMT and PAH (HMT-PAH1: 20% moisture, 90 °C; HMT-PAH2: 20% moisture, 110 °C; HMT-PAH3: 30% moisture, 90 °C; HMT-PAH4: 30% moisture, 110 °C). Pasting, functional, morphological and chemical properties of native and modified sweet potato starches were evaluated. Starch granules of native, single PAH, combined HMT-PAH2, HMT-PAH3-treated starches had identical granular sizes and smooth surfaces while other modified starches showed a rough surface with visible cracks. PAH promoted aggregation while combination of HMT and PAH treatments increased unevenness and rough surface on the starch granules. The peak and setback viscosities decreased in all modified starches while modification increased pasting ...