Polysaccharides-induced precipitation of protein from defatted roselle seed and its characterization: Antinutritional factors and functional properties

Abstract Defatted roselle seeds possess high protein content but they are usually discarded as waste. Based on the interaction of protein and polysaccharides, carrageenan, sodium alginate and carboxylmethyl cellulose were employed in protein precipitation to improve roselle protein recovery from roselle seed protein extract solution. Carrageenan showed the strongest effect in increasing the yield of protein precipitation. Under optimal conditions, the highest protein recovery was 95.59%, 92.45% and 82.60% obtained by using carrageenan, sodium alginate and carboxylmethyl cellulose, respectively. Carboxylmethyl cellulose–protein precipitate has the highest solubility, but carrageenan–protein precipitate showed the best suspension viscosity and foaming capacity. Using polysaccharide to precipitate roselle protein can also significantly reduce trypsin and phytate contents. However, it failed to reduce the amount of alpha-chymotrypsin and saponins.