Effects of Extraction Methods on Physicochemical and Structural Properties of Common Vetch Starch

Three extraction methods: water extraction, lactic acid bacteria fermentation, and back-slopping fermentation were applied to extract a new type of legume starch, common vetch starch. Our results showed that the lactic acid bacteria fermented starch had the highest amylose content (35.69%), followed by the back-slopping fermented starch (32.34%), and the water-extracted starch (30.25%). Furthermore, erosion surface, lower molecular weight, smaller particle size, larger specific surface area, and a higher proportion of B1 chain were observed in the fermented starch, especially in the back-slopping fermented starch. All the extracted starches showed a type C structure, but a type C_B structure was observed in the back-slopping fermented starch. In addition, the relative crystallinity of the lactic acid bacteria fermented starch (34.16%) and the back-slopping fermented starch (39.43%) was significantly higher than that of the water-extracted starch (30.22%). Moreover, the swelling power, solubility, pasting, and thermal properties of the fermented starches were also improved. In conclusion, the fermentation extraction method, especially back-slopping fermentation, could improve the quality of the extracted common vetch starch when compared with the traditional water extraction method.