Effect of heat moisture treatment on rheological and in vitro digestibility properties of pearl millet starches

Abstract

Pearl millet starches were modified using heat moisture treatment (HMT) (moisture content 25%, 110 °C at 3 h) and its structural and in vitro digestibility properties were studied. Amylose content, swelling power and solubility of starches were decreased after HMT. The results showed lower pasting viscosities for HMT starches as compared to native starches, thereby indicating their thermostability, and lower retrogradation capacity. G' values during heating and frequency sweep decreased after HMT. Yield stress and consistency index value ranged from 3.34 to 16.10 Pa and 5.5 to 21.2 Pa.s, the lowest value was observed for cv.HHB-67 and cv.GHB-732, respectively. Steady shear properties showed flow behavior index values <1 for starch pastes, indicating pseudoplastic and shear-thinning behavior. After modification, RS and SDS content increased and RDS content decreased as compared to their native counterpart starches. After HMT modification thermal stability and nutritional value of starches improved which enhance food applications of starches.

Keywords

• Pearl millet starch
• HMT
• Physicochemical
• Rheology
• Digestibility