Structure and Functional Properties of Cold Water Swelling Wheat Starch by Ethanol-Heat Treatment

The native wheat starch was dispersed into ethanol solutions of different concentrations (0, 10%, 20%, 30%, 40%, 50%) and heated at 80 ℃ for 30 min to prepare cold water swelling wheat starch. The crystal structure, functional properties (water holding capacity, oil holding capacity, gelatinization property, gel strength) and micromorphology of wheat starch by different ethanol concentration treatments were studied. The results showed that, the A-type crystal structure of natural wheat starch of X-ray diffraction pattern in 0~40% treatment group completely disappeared, 50% treatment group showed some diffraction peaks of natural wheat starch. This was consistent with the result of Fourier transform infrared spectrum. Meanwhile, as the concentration of ethanol increased from 10% to 40%, the water and oil holding capacity and gel strength of starch significantly increased (P<0.05), however, with the increasing of ethanol concentration to 50%, the water and oil holding capacity of starch significantly decreased (P<0.05). Furthermore, scanning electron microscopy showed that the number of cracks on the surface of 0~40% particles increased with the increasing of ethanol concentration, while 50% showed only wrinkles and no cracks on the surface. In conclusion, 40% ethanol concentration was the best method to prepare cold water swelling starch from wheat starch.