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Abstract
This study was carried out to prepare a good quality protein from cheap or waste sources by using protein isolates of these different sources. The highest protein solubility of all raw kinds was obtained in 0.1 M sodium hydroxide. Protein solubility of raw kinds was influenced by extraction time. The minimum solubility for germ flour, pumpkin seeds, soybean flour and Sardinella aurita fish was at pH 4.8, 5.4, 4.3 and 4.5 respectively. The chemical analysis of raw materials and protein isolates were investigated. Wheat germ protein isolate showed higher levels of Zn and Mn contents, while pumpkin seeds protein isolate had more K and Cu. The highest values of Fe and Ca contents were shown in soybean protein isolate as compared with other isolates. Sardinella aurita fish isolate was the good source of P. Soybean protein isolate had the highest values of all antinutritional factors as compared with other protein isolates. Sardinella aurita fish isolate revealed the highest value for chemical score, biological value and protein efficiency ratio as compared with other isolated proteins. Methionine + Cystine were the first limiting amino acids in all protein isolates except Sardinella aurita fish protein isolate. Sardinella aurita fish isolate was of the highest vitro protein digestibility. The isoelectric point for wheat germ, pumpkin seeds, soybean flours and Sardinella aurita fish protein isolates were at pH values 4.5, 5.1, 4.2 and 4.7, respectively., Foaming capacity for all protein isolates was increased in acidic and alkaline regions. In all protein isolates foam capacity increased as sodium chloride concentration increased, which reached to a maximum value and then decreased. The maximum foam capacity occurred at 1 M sodium chloride for all isolates. The foam stability of all protein isolates samples increased with sodium chloride concentration up to 1 M. Wheat germ protein isolate had higher value of water absorption capacity and fat absorption capacity than other isolates. Pumpkin seed protein isolate was the best to form gel more than both of wheat germ and soybean protein isolates. Sensory evaluation of products with protein blend (formula) revealed that the best formula was for 5.0 % protein blend level for pan bread and 10.0 % for pizza and biscuit. Farinograph and extensograph results showed significant differences among the addition of protein isolates to all formulae. Biological experiments were used to investigate the digestibility and biochemical analysis of best formula that consisted of 10.0 % protein isolates. PER, CPER, NPR, AD, TD, BV, NPU, urea, uric acid, and creatinine were estimated. No significant differences were observed between control group and experimental group for internal organs weights, full blood count, liver functions, serum end product of protein metabolism and serum lipids.