Enzymatic Extraction of Proteins and Amino Acids From Whole Fish and Fish Waste

Abstract

Fish and fish waste can be used to produce various value added by products such as proteins, oil, omega-3 fatty acids, biodiesel, amino acids, peptides, collagen, gelatin and silage, each of which has various applications in the food industry, renewable energy and medicinal purposes. Fish protein contains amino acids and many bioactive peptides . Fish proteins are found in the flesh, head, frames, fin, tail, skin and guts in varying quantities. After removing the flesh, all other parts are considered waste which is not properly utilized. The aim of this study was to evaluate the enzymatic extraction of amino acids from fish protein for use as substrates in the microbial production of jadomycin, an antimicrobial agent and potential anti-cancer drug. In this study, enzymatic extraction of proteins was carried out using Alcalase enzyme at three enzyme concentrations (0.5, 1 or 2%) and four time intervals (1, 2, 3 and 4 h). The fish protein hydrolysate was dried using spray dryer to obtain protein powder. The highest protein yield (76.30% from whole fish and 74.53% from the frame) was obtained using 2.0% enzyme concentration after 4 h of hydrolysis. The enzymatic extraction of amino acids were carried out using the enzymes Alcalase and Neutrase (individually and in combination) and the effect of reaction time (24 and 48 h) on the hydrolysis of proteins was studied. The profiling of amino acids was carried out using gas chromatography. Fourteen amino acids were extracted from fish proteins of which twelve amino acids have been used by researchers for the production of jadomycins. These are: alanine (7.59%), glycine (5.82%), histidine (3.59%), isoleucine (5.30%), leucine (9%), lysine (7.34%) methionine (2.2%), phenylalanine (4.2%), serine (4.3%), threonine (5.40%), tyrosine (3.17%) and valine (7.2%). Tryptophan which is suitable of producing jadomycin was not present in the fish protein. No reports were found in the literature for jadomycin production from glutamic acid. Therefore, glutamic acid (9.85%), and proline (0.98%) which are present in the fish protein should be investigated for possible production of jadomycins.