ABSTRACT

 Pumpkin (Curcubita pepo') seed was processed into defatted flour (CPF), which was further processed into protein concentrate (CPC), and protein isolate (CPI) using alkaline water/isoelectric precipitation. The nutritional and functional properties ofthese products were evaluated. The defatted flour as composite with wheat in cookie production was evaluated. Results indicated that the protein content of CPF, CPC, and CPI were 57.50%, 69.98% and 74.15% while the ash contents were 5.38%, 1.24% and 5.50%, respectively with the defatted flour having high mineral content. CPC and CPI demonstrated high vitamin C content of 43.46 mg/ml and 52.36 mg/ml respectively. All the samples were high in vitamin A but low in thiamin and riboflavin. Percentage ratio of essential to total amino acids of CPF, CPC and CPI were 43.27, 44.24 and 45.50, respectively. Threonine and lysine were the most limiting amino acids in all the samples. Anti-nutrients present in CPF, CPC and CPI include tannin (0.69%, 0.76%, 0.88%); saponin (0.56%, 0.54%, 0.51%); HCN (4.08%, 3.45%, 3.98%); trypsin inhibitor (2.07, 2.18, 2.06 TIU/g); Phytate (0.44%, 0.10%, 0.14%); stachyose (3.00%, 2.80%, 0.80%) and raffinose (0.80%, 0.70%, 0.20%), respectively and these values are below allowable limits. All samples exhibited a broad range of minimum protein solubility at pH 6-8 and maximum at pH 10. The most stable emulsions were obtained at pH 12 and at 0.1%, 0.5% and 1.0% sample concentrations in all the samples. Maximum foaming capacity was obtained at pH 2.0 in all the samples. Peak viscosity ranged from 32.83-44.25 RVU and was significantly different in all the samples while the breakdown value and pasting temperature showed no significant differences (p>0.05). Cookie diameter negatively correlated with alkaline water retention capacity of Cucurbita pepo seed/wheat flour blends with correlation coefficient of -0.89. Physicochemical and sensory evaluation revealed that up to 10% substitution of wheat flour with defatted Cucurbita pepo seed flour produced acceptable cookies similar to the control (100% wheat flour).