Impact of octenyl succinylation on rheological, pasting, thermal and physicochemical properties of pearl millet (Pennisetum typhoides) starch

Abstract

The impact of octenyl succinic anhydride (OSA) esterification was investigated on rheological, pasting, thermal and physicochemical properties of pearl millet (Pennisetum typhoides) starch. Starch was esterified with 3% OSA at four reaction times viz. 2 (OSA-2H), 3 (OSA-3H), 4 (OSA-4H), and 5 h (OSA-5H). Degree of substitution (DS) increased significantly (p < h.05) from 0.018 to 0.022 with increasing reaction time and peak height at 1724 cm−1 in fourier transform infrared spectroscopy increased with increase in DS. Resistant starch and oil absorption capacity increased significantly (p < 0.05) from 2.41 to 13.72% and 1.31–2.67 g/g, respectively with increasing DS. Significant increase was observed in peak, hot paste, cold paste and breakdown viscosity upon OSA esterification while, pasting temperature and setback ratio decreased. Storage modulus, loss modulus and strain increased upon OSA esterification. Herschel Bulkley model was found best fitted with R2 values 0.997 and 0.995 for native and OSA-3H (DS 0.0208) gels, respectively. Consistency index decreased from 13.57 to 2.25 and 27.30 to 1.84 for native and OSA-3H, respectively with increase in temperature from 5 to 85 °C. Gelatinization temperature and enthalpy of gelatinization decreased significantly. OSA-starch gels exhibited good proportioning, homogeneous mixing and self leveling characteristics making them potential fat replacers.