Physicochemical and functional properties of pigeon pea (Cajanus cajan) protein and non-starch polysaccharides

Pigeon pea (Cajanus cajan L. Millsp) has been commonly consumed in human diet, and it is also a promising source of protein and dietary fibers. In this study, pigeon pea protein and non-starch polysaccharides (NSP) were sequentially extracted and fractionated. The amino acid profile of protein was characterized, and total sugars and uronic acid of non-starch polysaccharides were identified. Physicochemical properties of pigeon pea protein were compared with commercial soy protein isolates; meanwhile, pigeon pea NSP was compared with commercial citrus pectin. The results indicated that the viscosity of protein solution from pigeon pea is higher than that from soy protein isolates at all concentrations and exhibited shear-thinning behavior at shear rate range 0.1–500 s−1. The emulsions prepared from pigeon pea protein at the concentrations of 0.5% and 2% (w/w) displayed significant higher emulsifying stability (p < 0.05) than those of soy protein. Pigeon pea polysaccharide exhibited higher surface activity than citrus pectin, with the 0.5% pigeon pea polysaccharide solution comparable with 1.5% citrus pectin solution. The results of this study have implied great potentials of application of pigeon pea protein and non-starch polysaccharide as novel ingredients for food industries.