Effects of different drying methods on physicochemical and sizing properties of granular cold water swelling starch

Granular cold water swelling starch (GCWS) can be converted from native starch by oven-dried and freeze-dried methods, respectively, after the alcoholic-alkaline treatment. The main aim of this research was to investigate and compare the physicochemical properties of the GCWS made through two different drying methods, including morphological properties, Fourier transform infrared spectroscopy, cold water solubility, thermal analysis and pasting properties. Then cotton yarns were sized by the two types of GCWS. Size pick-up, breaking strength, abrasion resistance and hairiness of sized yarns were respectively tested. Experimental results revealed that the alcoholic-alkaline treatment destroyed the crystalline structure without new groups being generated; the appearances of the GCWSs were significantly affected by the drying methods; the cold water solubility of freeze-dried GCWS was significantly larger than that of oven-dried GCWS, while freeze-dried GCWS showed lower retrogradation. In addition, it also indicated that the method of freeze-dried operation to prepare GCWS can effectively improve the sizing properties of cotton yarns