Optimization of Preparation of Broad Bean Resistant Starch by Thermal-press Processing Method and Its Structural Analysis

In this paper,the effects of five factors on the yield of resistant starch in broad bean were studied by single factor test,including the concentration of starch emulsion,the temperature of pressure heating,the time of pressure heating,the retrogradation temperature and the retrogradation time. On this basis,the preparation process was optimized by response surface test,and the structure characterization of resistant starch was further analyzed by X-ray diffraction,Fourier infrared spectroscopy and scanning electron microscope. The results showed that the best preparation technology for resistant starch of broad bean was as follows:The concentration of starch emulsion 31%,pressing and heating at 121 ℃ for 38 min,and retarding at 4 ℃ for 32 h. Under this condition,the yield of resistant starch was 26.80%±0.82%,which was close to the predicted value 26.13%±1.50%,which proved that the response surface model fitted well with the actual situation. X-ray diffraction results showed that broad bean starch granules were ellipsoid and A type starch. The resistant starch granules were irregular lamellar or polygonal stacked blocks,and they were type C starch. Fourier infrared spectroscopy spectra showed that there was no chemical reaction,but a lot of intermolecular hydrogen bonds were generated during the preparation of resistant starch of broad bean. In conclusion,the results of this experiment can provide references for the preparation and development of resistant starch in broad bean.