Production of fish protein hydrolyzate for use as fortifying agent in some food products

Silver carp fish was used as a raw material for preparing protein hydrolyzate by two methods: 1] Autlysis in the presence of sodium chloride or without it at 65 °C and 2] Enzymatic hydrolysis using two proteolytic enzymes, pepsin or papain to obtain fish protein hydrolyzate under controlled conditions. The obtained papain protein hydrolyzate had high quantity and quality as compared with the other produced hydrolyzates. The obtained hydrolyzate was used for fortification of Egyptian shamy bread and biscuit as source of essential amino acids. It was added in different levels [2-4%] for shamy bread and [0.5-5.0%] for biscuits. Chemical, nutritional and organoleptic properties of supplemented shamy bread and biscuit were evaluated and the results were as follows: 1-Produced silver carp protein hydrolyzates contained [64.69-93.9 1%] protein, [0.44-0.87%] fat, [4.91-33.01%] ash and [0.54-3.37%] carbohydrates [on dry weight basis] depending on the method of hydrolysis used. Also, the amino acid composition of papain fish protein hydrolyzate contained the following amino acids [gm/100 gm protein]: Isoleucine 4.72, leucine 8.64, lysin 8.74, threonine 4.67, valine 4.96, histidin 3.20, methionine+cystine 5.59 and phenylalanine+tyrosine 7.92. 2-Organoleptic evaluation revealed that shamy bread and biscuit samples fortified with 4% and 5% silver carp protein hydrolyzate, respectively were the best among all examined treatments; hence both contained more protein and essential amino acids contents