Volume 5(4): 107-129 (2013) - 107 J Microb Biochem Technol ISSN: 1948-5948 JMBT, an open access journal Research Article Open Access Ghaly et al., J Microb Biochem Technol 2013, 5:4 http://dx.doi.org/10.4172/1948-5948.1000110 Review Article Open Access Microbial & Biochemical Technology *Corresponding author: Dr. Abdel Ghaly, Department of Process Engineering and Applied Science, Faculty of Engineering, Dalhousie University, Halifax, Nova Scotia, Canada, Tel: (902)494-6014; E-mail: abdel.ghaly@dal.ca Received September 25, 2013; Accepted November 09, 2013; Published November 15, 2013 Citation: Ghaly AE, Ramakrishnan VV, Brooks MS, Budge SM, Dave D (2013) Fish Processing Wastes as a Potential Source of Proteins, Amino Acids and Oils: A Critical Review. J Microb Biochem Technol 5: 107-129. doi:10.4172/1948- 5948.1000110 Copyright: © 2013 Ghaly AE, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited Abstract The ish processing industry is a major exporter of seafood and marine products in many countries. About 70% of the ish is processed before inal sale. Processing of ish involves stunning, grading, slime removal, deheading, washing, scaling, gutting, cutting of ins, meat bone separation and steaks and illets. During these steps signiicant amount of waste (20-80% depending upon the level of processing and type of ish) is generated which can be utilized as ish silage, ishmeal and ish sauce. Fish waste can also be used for production of various value added products such as proteins, oil, amino acids, minerals, enzymes, bioactive peptides, collagen and gelatin. The ish proteins are found in all parts of the ish. There are three types of proteins in ish: structural proteins, sacroplasmic proteins and connective tissue proteins. The ish proteins can be extracted by chemical and enzymatic process. In the chemical method, salts (NaCl and LiCl) and solvents (isopropanol and aezotropic isopropanol) are used, whereas during the enzymatic extraction, enzymes (alcalase, neutrase, protex, protemax and lavorzyme) are used to extract proteins from ish. These ish proteins can be used as a functional ingredient in many food items because of their properties (water holding capacity, oil absorption, gelling activity, foaming capacity and emulsifying properties). They can also be used as milk replacers, bakery substitutes, soups and infant formulas. The amino acids are the building blocks of protein. There are 16-18 amino acids present in ish proteins. The amino acids can be produced from ish protein by enzymatic or chemical processes. The enzymatic hydrolysis involves the use of direct protein substrates and enzymes such as alcalase, neutrase, carboxypeptidase, chymotrypsin, pepsin and trypsin. In the chemical hydrolysis process, acid or alkali is used for the breakdown of protein to extract amino acids. The main disadvantage of this method is the complete destruction of tryptophan and cysteine and partial destruction of tyrosine, serine and threonine. The amino acids present in the ish can be utilized in animal feed in the form of ishmeal and sauce or can be used in the production of various pharmaceuticals. The ish oil contains two important polyunsaturated fatty acids called EPA and DHA or otherwise called as omega-3 fatty acids. These omega-3 fatty acids have beneicial bioactivities including prevention of atherosclerosis, protection against maniac–depressive illness and various other medicinal properties. Fish oil can also be converted to non-toxic, biodegradable, environment friendly biodiesel using chemical or enzymatic transesteriication. Fish Processing Wastes as a Potential Source of Proteins, Amino Acids and Oils: A Critical Review Ghaly AE*, Ramakrishnan VV, Brooks MS, Budge SM and Dave D Department of Process Engineering and Applied Science, Faculty of Engineering Dalhousie University, Halifax, Nova Scotia, Canada Keywords: Fish; Fish processing; Fish waste; Storage; Slime; Rigor mortis; Autolysis; Protein; Amino acids; Collagen; Oil; Enzymes; Silage; Enzymatic hydrolysis; Enzyme membrane reactor Introduction he ish processing industry in Canada is amajor exporter of seafood and marine products. Canada exports 75% of its ish products to more than 80 countries. In the year 2012, exports from Canada amounted to 595,615.738 metric tonnes of ish worth $4.15 billion [1]. Canada has the world’s longest coastline (244,000 km) which makes 25% of the entire world's coastline. Atlantic Canada represents 40,000 km of coastline which comprises four major provinces. It exports high quality harvested ground ish, shellish and pelagic ish accounting for 85% of the total Canadian ish landings [2]. he Paciic ishery accounts for 14% of the total ish landings and includes cod, redish sp., latish, hake, herring, tuna, salmon and calms. he freshwater ishery accounted for 1% of the total landings and includes perch, pike, whiteish, yellow pickerel and smelt. he aquaculture production in Canada for the year 2011 reached 161,036 tonnes worth $845,598 [3]. he world marine capture isheries contribute more than 50% of the total world ish production. About 70% of ish is processed before inal sale, resulting in 20-80% of ish waste depending on the level of processing and type of ish [4]. In addition, a signiicant amount of the total catch from ish farming is discarded each year. Also, ish processing operation require large volumes of potable water which results in signiicant amounts of waste water [5]. he majority of ish wastes are disposed of in the ocean. he aerobic bacteria present in the water breakdown the organic matter in the presence of oxygen leading to a considerable reduction of oxygen in water. here are also overloads of nitrogen, phosphorous and ammonia, which lead to pH variation, increased turbidity of the water and as a result of the decomposition of algae. he reduction in water oxygen content creates an anaerobic condition that leads to the release of foul gases such as hydrogen sulide and ammonia, organic acids and greenhouse gases such as carbon dioxide and methane [6]. he discards from the processing plants amount to 20 million tonnes which is equivalent to 25% of the world’s total production from marine capture isheries [4]. hese wastes can be used to produce ish protein concentrate, ish oils and enzymes (such as pepsin and chymotrypsin) as well as other value added products. he ish oil is used for products such as margarine, omega-3 fatty acids and biodiesel.