Functional properties of Chinese yam (Dioscorea opposita Thunb. cv. Baiyu) soluble protein.

In this study, yam soluble protein (YSP) was extracted from Chinese yam (Dioscorea opposita Thunb. cv. Baiyu) and the functional properties were investigated under the influence of pH and ionic strength. As results, YSP was highly soluble and had better emulsifying activity over a wide range of pH. The solubility of YSP decreased in 0.5 and 1.0 M NaCl solution. An increment in NaCl concentration reduced the emulsion activity index and emulsion stability index of YSP. The oil absorption capacity of YSP was 3.2 ml/g protein. With the increase of pH, the foam capacity (FC) and stability (FS) decreased and then increased. FS of YSP increased as the salt concentration increased from 0 to 0.5 M, and then decreased. The minimal gelation concentration of YSP was 8% (w/v) and 10% YSP gel (w/v) had maximum gel strength in 0.1 M NaCl. These results suggested that YSP produced by acid precipitation may be used as a protein source with remarkable functional properties.