Effect of octenylsuccinylation on physicochemical, thermal, morphological and stability of octenyl succinic anhydride (OSA) modified sago starch

Abstract

Sago starch (Metroxylon sagu) and gelose 80 starches were esterified with octenyl succinic anhydride (OSA) and effect of the reaction was evaluated in terms of physicochemical properties. The degree of substitution (DS) of 0.0120 was obtained for OSA sago starch and 0.0145 for OSA gelose 80 starch. The amylose content of OSA starches (OSA sago starch: 25.27%; OSA gelose 80: 70.70%) was found to decrease significantly (p < 0.05) compared to native starches (Sago starch: 30.18%; Gelose 80: 78.47%). FTIR spectroscopy showed two new peaks on OSA starches spectrum at 1720 cm−1 and 1566 cm−1 due to C=O and RCOO-, respectively. The particle size of both OSA starches significantly (p < 0.05) increased (OSA sago starch = 29.89 μm, OSA gelose 80 = 20.37 μm) due to structural disorder that happens after modification. The surface tension for OSA sago starch was found to be 58.40 mN/m while OSA gelose 80 was 54.87 mN/m. The gelatinisation temperature and enthalpy for OSA sago starch and gelose 80 starch ranged from 67.56 °C to 79.83 °C (enthalpy: 10.25 J/g) and 65.69 °C to 95.26 °C (enthalpy: 7.45 J/g), respectively with reduction pattern was observed for both starches. The morphology of starch granule examined by scanning electron microscopy (SEM) showed some rough surface and a few changes in shape of OSA starches. To confirm the success of the esterification on the sago starch, the physicochemical properties of OSA commercial starch was used as a comparison.