Preparation of V-type cold water-swelling starch by ethanolic extrusion

Ethanolic extrusion was used to prepare V-type cold water-swelling starch (VCWSS). Effects of extrusion temperature, ratio of starch to ethanol, and ratio of starch to water on the properties of VCWSS were investigated. It was found that when the extrusion temperature was 100 °C, the ratio of starch to ethanol was 1:0.30, and the ratio of starch to water was 1:0.60, the resulting VCWSS could quickly swell into paste in cold water with the highest V-type relative crystallinity (12.90%) and cold paste viscosity (3058 cP). Then the formation mechanism of cold paste viscosity of VCWSS was evaluated. The cold paste viscosity of VCWSS was positively related to its V-type relative crystallinity. Extrusion destroyed the granular morphology of native starch, and VCWSS particles exhibited rock-like morphology that is much larger than the granules of native starch. Formation of the V-amylose-ethanol complex during extrusion was the direct cause of rapid hydration of VCWSS.