Abstract: Protein isolates from bran (B-pro) and perisperm (S-pro) of sand rice seeds (Agriophyllum squarrosum) were obtained by alkali extraction/isoelectric precipitation, and their physicochemical and functional properties were evaluated in this study. The results indicated that albumin was higer in the bran, and globulin was higer in the perisperm. The protein contents of B-pro and S-pro were 94.33% (md) and 91.80% (md), respectively and the color of S-pro was more brighter and whiter. Both B-pro and S-pro were rich in essential amino acids and the content of lysine in S-pro was higher than that in B-pro. The functional properties of the two protein isolates were greatly pH dependent like other plant proteins. In general, most of the functional properties of S-pro were superior to those of B-pro at different pH values. Compared to soybean protein isolate (SPI) and egg protein (EP), B-pro and S-pro showed better oil-holding capacity and foaming capacity at pH 7.0, but poorer solubility, water-holding capacity and emulsification capacity.

Key words: sand rice, bran protein, perisperm protein, physicochemical properties, functional properties