Biochemical, nutritional and functional properties of protein isolate and fractions from pumpkin (Cucurbita moschata var. Kashi Harit) seeds.

Pumpkin seeds are rich source of nutritionally well-balanced proteins. The biochemical, nutritional, and functional properties of the protein isolate (PPI) and protein fractions from pumpkin seed were evaluated. Extraction method for PPI was optimized by varying NaCl (0, 0.5, 1 M) and flour-to-solution ratio (1:5, 1:10, 1:25), at pH 9.0. Proteins were extracted by Osborne procedure and the alkali fraction (AF, 45.82%) was found to be the predominant fraction. SDS-PAGE profile of PPI revealed major bands ranging from 50 to 7 kDa. AF contained all the essential amino acids (EAA) except lysine and threonine, as required by pre-school children (FAO/WHO). PPI and AF showed better protein efficiency ratio and EAA/TAA (total) %, indicating the presence of good quality proteins. Functional properties were found to be comparable with soybean protein isolate. Circular dichroism studies showed that water fraction comprised of α-helix and random coils, while salt and alkali fractions contained β-strand and coils.