Maximising the Value of Marine By-Products || Maximizing the value of marine by-products: an overview

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The world's annual catch of fish and marine invertebrates has been around 100million metric tonnes in recent years. However, aquaculture developments haveled to production of high quality products that have also assisted conservationstrategies to be implemented. Of the total amount of harvest, a major portionremains unused or used for production of fish meal and fish oil. This is due tothe fact that certain species might suffer from small size, high bone, skin and fatcontents as well as unappealing shape. In addition, several species of fish may beused for their roe and production of caviar. The leftover carcass following roeextraction as well as those of their male counterparts may be discarded.Furthermore, processing discards from many species of fish and shellfish couldbe successfully processed for production of specialty enzymes, xanthophylls,chitin/chitosan, glucosamine and other value-added products. Thus, devising ofstrategies for full utilization of the catch and processing of discards forproduction of novel products is warranted (Shahidi, 2000).Seafood processing by-products and their useThe seafood processing industry is still producing a large quantity of by-products and discards. These include heads, tails, viscera and backbone as wellas shells. Utilization of these processing by-products may be exercised indifferent ways leading to1. production of animal and aquaculture feed, similar to that used for wholefish when producing fish meal and fish oil,Maximizing the value of marineby-products: an overviewF. Shahidi, Memorial University of Newfoundland, Canada2. production of food ingredients such as extraction of cheeks and tongue fromcod and production of surimi from frames and3. production of novel and value-added products for nutraceutical, pharma-ceutical and fine chemical industries (Table I.1).Novel and specialty products with potential biological activity and/orfunctionality provide a means for value-added utilization of by-products. Thesemay be used as food ingredients to take advantage of a specific flavour, such asthose from cook water of crab and lobster (Jayarajah and Lee, 1999; Yang andLee, 2000), or for rendering a specific functional property such as water-holding,foaming, emulsifying and gelling properties. The use of by-products as healthfood ingredients may be for nutritional purposes; these include proteins, lipids,mineral and vitamins. Finally, by-products may be employed for nutraceuticaland specialty applications. In this category, protein hydrolyzates, fish oils,hormones, glucosamine, chitin/chitosan, flavourants and enzymes as well asother physiologically active ingredients may be included. The following sectionsprovide a cursory account of current and potential uses of by-products indifferent applications and for rendering health benefits.Proteins from seafoods and their by-productsSeafood by-products are an excellent source of high quality proteins that maysupply a major part of the essential amino acids that are required for a balancednutrition. Recovery of proteins from by-products may be carried out by differentprocesses using mechanical separation from frames, base extraction or hydrolysis.While hydrolysis of fish proteins by endogenous enzymes prior to or duringprimary processing may lead to fish quality deterioration, such processes may beintentionally carried out to produce specialty products. Thus, production of fishsauce and silage from fish and processing discards is commonplace. In addition,enzymes that are commercially available may be used to produce proteinhydrolyzate that could be used in a variety of applications. Protein hydrolyzatesare nearly colourless and appear like milk powder; they may be used inTable I.1 Physiological components from marine by-productsIngredient Application areaProteins/biopeptides Nutraceuticals, immune-enhancersMinerals/calcium Food, nutraceuticalsChitosan, glucosamine Nutraceuticals, agriculture, food, water purificationOmega-3 oils Nutraceuticals, dietary supplements, foodCarotenoids/xanthophylls Nutraceuticals, fish feedChordprotein sulphate Supplements, arthritic pain reliefSqualene Skin careSpecialty chemicals Miscellaneousxxii Maximizing the value of marine by-products: an overviewapplications where water solubility and water-holding capacity are important.Protein hydrolyzates may possess biological activity in enhancing immuneresponse and may also render antioxidant as well as angiotensin convertingenzyme (ACE) inhibitory activity (Je et al., 2004) among others.Carotenoids (C40H56) and their oxygenated derivatives (xanthophylls) areanother group of bioactives that are present in salmonid fish, crustaceans andtheir processing by-products, among others (Shahidi et al., 1998). These areoften present in combination with proteins, known as carotenoproteins. Extrac-tion and isolation of carotenoproteins as ingredients for potential use in salmonidfish aquaculture has been reported (Cremades et al., 2003).Digestive proteases from fish and shellfish processing discards may be usedas industrial processing aids (Shahidi and Kamil, 2001). Suggested uses ofdigestive proteases from fish include acids for cheese making, herring fermenta-tion, fish skinning, roe processing and production of specialty kits, as well asmedical applications.Lipids from processing by-productsSeafood lipids provide unique health benefits to consumers, but also present achallenge to scientists and technologists for delivering their highly unsaturatedfatty acids (HUFA) in an odour-free and appealing form. The oils originate fromthe body of fatty fish as a by-product of fish meal industry, liver of white leanfish such as those of cod and halibut, and finally blubber of marine mammalssuch as seals and whales. Viscera from fish also provide for a rich source oflipids. These lipids include a high proportion of long-chain polyunsaturated fattyacids (LC PUFA) belonging to the omega-3 family, namely eicosapentaenoicacid (EPA), docosapentaenoic acid (DPA) and docosahexaenoic acid (DHA).There is a rapidly growing body of literature illustrating the health benefits ofHUFA. These effects include protection against cardiovascular disease, auto-immune and mental disorders, diabetes, arthritis and arrhythmia, among others(Shahidi and Finley, 2001; Shahidi and Miraliakbari, 2004, 2005).Marine lipids are highly prone to oxidation, hence their processing underrelatively mild conditions and stabilization following refining, bleaching anddeodorization is recommended. This is partly due to the fact that the refiningprocess leads to the removal of endogenous antioxidants from the oil and hencereplenishment with antioxidants, particularly those from natural sources isimportant. In addition, microencapsulation of the oils may prove useful whensuch oils are to be used in fortification of food and beverages.Minerals and chitinous materialsSeafood processing discards contain a large proportion of frames as well asshells that are primarily composed of calcium salts. Thus, the resultant calciumMaximizing the value of marine by-products: an overview xxiiimay be solubilized and potentially used for addressing concerns about bonehealth due to insufficient intake of calcium. Jung and co-workers (2006) haveclearly demonstrated the solubilization of calcium from fish frames and theirbenefits.Most shellfish, especially those from shrimp, crab, lobster and crayfish con-tain a large amount of chitin that may be recovered following deproteinizationand demineralization. The recovered chitin may be used for chitosan productionusing concentrated base or render pressure, glucosamine preparation or chitosanoligmers, short-chain copolymers of glucosamine and N-acetylglucosamine andderivatives thereof.Glucosamine, the monomer of chitosan, has been reported to possess benefitsfor joint health and build up as well in wound-healing, among others. Theproduct is generally sold as glucosamine sulphate, but this is often a mixture ofglucosamine hydrochloride and sodium or potassium sulphate. Furthermore,glucosamine may be sold in combination with chondroitin 4- and 6-sulphates.Chondroitins are mucopolysaccharides (MPs) with molecular weights of up to50,000 Da and could be prepared from connective tissues of slaughtered animalsand seafoods (Jo et al., 2005). In combination, while glucosamine helps to formproteoglycans that sit within the space in the cartilage, chondroitin sulphate actsas a liquid magnet (Shahidi and Kim, 2002).Future trends and prospectsDwindling supply of seafoods from the wild dictates full utilization of theharvest. In addition, the advent of aquaculture allows a better control over theharvest time and hence better quality of products, including processing by-products. A stricter environmental restriction on dumping of discards also servesas a further incentive to explore novel uses of products that might otherwise beconsidered uneconomical. Low temperature activity of enzymes as well asunique characteristics of products from processing discards might also catalyzenew developments in value-added utilization of specialty products fromprocessing lines.ReferencesCREMADES, O., PARRADO, J., ALVAREZ-OSSORIO, M.C., JOVER, M., COLLANTES-DE-TERAN, L.,GUTIERREZ, J.F. and BAUTISTA, J. 2003. Isolation and characterization ofcarotenoproteins from crayfish (Procambarus clarkii). Food Chem. 82, 559566.JAYARAJAH, C.N. and LEE, C.M. 1999. Ultrafiltration/reverse osmosis concentration oflobster extract. J. Food Sci. 64, 9398.JE, J.Y., PARK, P.J., KWEN, J.Y. and KIM, S.K. 2004. A novel angiotensin converting enzymeinhibitory peptide from Alaska pollack (Theragra chalcogramma) frame proteinhydrolysate. J. Agric. Food Chem. 52, 78427845.xxiv Maximizing the value of marine by-products: an overviewJO, J.H., DO, J.R., KIM, Y.M., KIM, D.S., LEE, T.K., KIM, S.B., CHO, S.M., KANG, S.V. and PARK, D.C.2005. Optimization of shark (squatina oculata) cartilage hydrolysis for thepreparation of chondroitin sulfate. Food Sci. Biotechnol. 14, 651655.JUNG, W.K., LEE, B.J. and KIM, S.K. 2006. Fish-bone peptide increases calcium solubility andbioavailability in ovariectomised rats. British J. Nutr. 95, 124128.SHAHIDI, F. 2000. Seafood in Health and Nutrition Transformation in Fisheries andAquaculture: Global Perspectives. ScienceTech Publishing Co., St. John's, NL,Canada.SHAHIDI, F. and FINLEY, J.W. 2001. Omega-3 Fatty Acids: Chemistry, Nutrition, and HealthEffects. ACS Symposium Series 788, p. 330. American Chemical Society,Washington, D.C.SHAHIDI, F. and KAMIL, Y.V.A.J. 2001. Enzymes from fish and aquatic invertebrates andtheir application in the food industry. Trends Food Sci. Technol. 12, 435464.SHAHIDI, F. and KIM, S-K. 2002. Quality management of marine nutraceuticals. In C-T. Hoand Q.T. Zheng (eds), Quality Management of Nutraceuticals. ACS SymposiumSeries 803, pp. 7687. American Chemical Society. Washington, DC.SHAHIDI, F. and MIRALIAKBARI, H. 2004. Omega-3 (n-3) fatty acids in health and disease:Part 1 Cardiovascular diseases and cancer. J. Med. Food 7, 387401.SHAHIDI, F. and MIRALIAKBARI, H. 2005. Omega-3 fatty acids in health and disease: Part 2 Health effects of omega-3 fatty acids in autoimmune diseases, mental health andgene expression. J. Med. Food 8, 133150.SHAHIDI, F., METUSALACH and BROWN, J.A. 1998. Carotenoid pigments in seafoods andaquaculture. Crit. Rev. Food Sci. Nutr. 38, 167.YANG, Y. and LEE, C.M. 2000. Enzyme-assisted bioproduction of lobster flavor from theprocess by-product and its chemical and sensory properties. In Shahidi, F. (ed.),Seafood in Health and Nutrition Transformation in Fisheries and Aquaculture:Global Perspectives. ScienceTech Publishing Co., St. John's, NL, Canada, pp.169194.Maximizing the value of marine by-products: an overview xxv

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