Kinetic study of the nonthermal effect of the esterification of octenyl succinic anhydride modified starch treated by microwave radiation

摘要

With cassava starch as a raw material and octenyl succinic anhydride as an esterifying agent, octenyl succinic anhydride modified starch (OSA-starch) was prepared in an aqueous medium and treated by water-bath heating and microwave radiation at a certain temperature, respectively. The reaction kinetics of esterification were studied. The structural analysis and synthesis mechanism of OSA-starch were investigated by means of scanning electron microscopy and Fourier transform infrared spectroscopy. The differences in the esterification reaction kinetics between starches treated with water-bath heating and microwave radiation were observed. Under the condition of water-bath heating, the apparent activation energy of the esterification reaction was 52.22 +/- 1.21 kJ/mol, and the pre-exponential factor was 9018.20/min(-1). Under the condition of microwave radiation, the apparent activation energy of the esterification reaction was 50.13 +/- 1.16 kJ/mol, and the pre-exponential factor was 4510.21/min(-1). We found that microwave radiation could reduce both the activation energy of the reaction and the pre-exponential factor. The lowering effect of the apparent activation energy was greater than that of the pre-exponential factor under the condition of microwave radiation, and this resulted in increased reaction rates. The change in the esterification reaction kinetics was a nonthermal effect of microwave radiation on the esterification of cassava starch. (C) 2016 Wiley Periodicals, Inc.