The Effect of Heat-Moisture Treatment (HMT) on the Structural, Functional Properties and Digestibility of Citric Acid-Modified <i>Plectranthus rotundifolius</i> (Hausa Potato) Starch

Abstract

In this study, Hausa potato starch was subjected to single and dual modifications by HMT and citric acid. The parameters such as relative crystallinity, pasting, functional properties, and in vitro digestibility were studied. The XRD analysis showed an A-type diffraction pattern for the native starch and was unaffected by all modifications. The relative crystallinity and the gelatinization enthalpy significantly decreased (p ≤ 0.05) on dual modification. A new peak at 1724 cm−1 was observed in the FT-IR spectra of citric acid-modified starch. The peak intensity became stronger in HMT followed by citric acid-modified starch, which was consistent with the results of degree of substitution. The native starch showed a peak viscosity of 3343 cP and significantly decreased on citric acid modification, and HMT treatment increased the effectiveness of the citric acid modification. The in vitro digestibility of Hausa potato starch was significantly affected by both single and dual modifications. The increased DS and RS content of the dual-modified starch suggests that the HMT served as a pre-treatment and favored the production of the citrate starch. The HMT-citric acid dual modification method was shown to modify the starch properties and could be used as a substitute for producing low glycaemic index foods.

Keywords

• <i>Plectranthus rotundifolius</i> starch
• heat-moisture treatment
• citric acid-modification
• digestibility