New uses for marine by-products assessed

Christian Pérez According to this paper, published in Trends in Food Science & Technology and quoted by the IFFO, some products can be used directly as food but many are made into feed ingredients. Apart from the traditional use of by-products as feed ingredients like fishmeal, fish protein concentrates and fish oil, there has been increased focus on transforming this biomass into isolated functional or biologically active (bioactive) components to be used for example as dietary supplements (nutraceuticals), as processing aids and even as pharmaceutical products. As in all kinds of production, transformation of by-products into commercial products must be market-driven with a realistic possibility of being sold with an economic margin within a reasonable time period. Recovery of by-products Recovery of by-products is challenging due to their rapid deterioration particularly in products containing viscera. The viscera of fish that is gutted at sea are often discarded due to inadequate processing facilities whereas some fish species caught in coastal waters are often processed fresh ashore which allows for better utilisation of by-products. By-products as food or feed Examples of progress in turning by-products into food for humans are tuna processing where the nutritionally rich dark meat is canned and exported and traditional by-products like heads, tails, livers, hearts and roes are sold for human consumption in domestic markets and the aquaculture industry where in some regions up to 24% of the salmon by-products are used for human consumption, while the rest are processed into feed ingredients. The value of original low value fishmeal or fish protein hydrolysates and fish oil has increased and in 2010 up to 36% of production came from by-products. Liquid silage production is an alternative way to preserve viscera containing by-products especially if the by-product volumes do not justify traditional fishmeal processing. Silage from small volumes of by-products can be combined so that sufficient volumes can be processed into oil and concentrated fish protein hydrolysate to be used together with the oil in formulated feed for pigs, poultry and farmed fish other than salmon. Functional and bioactive ingredients from by-products Although a large number of scientific reviews have published on the possibilities of producing high-value products like collagen and gelatine, chitin and chitosan, enzymes and specific proteins, bioactive peptides and pigments from processing of marine by-products, very few high-value products have become established on the market and are sold in larger quantities. The lack of market presence is due to the overestimation of market possibilities, limited availability of high quality by-products along with high isolation costs of specific components. The nutraceutical market is particularly hard to penetrate because of the high cost in providing the necessary documentation for health claims which requires that evidence must be obtained from studies on humans. Up to date the most successful bioactive components isolated from marine sources are the long-chain omega-3 fatty acids (LC-PUFAs) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Many of the omega-3 fatty acids are sold in up to 85% concentrated forms either as ethyl esters (EE) or triacylglycerols. Lipid-rich by-products of marine wild fish are therefore a suitable source of omega-3 fatty acids if large amounts of by-products are available. Alternative functional or bioactive ingredients has had limited success. Collagen from marine and other sources is mainly denatured to gelatine and used for pharmaceutical purposes and as a functional food ingredient but comprises of only 1.5% of the gelatin annual production. Similarly chitin and chitosan, biopolymers present in the shells of crustaceans, have potential applications in many diverse areas such as food technology, as medical products, in cosmetics and in industrial processes but has shown little actual market presence. The reason for the limited success can be attributed to slightly different physical properties of the marine derived products, variable quality especially if by-products from different species are pooled along with insufficient supply of raw materials from specific species on a regular basis and higher prices due to the high cost of the production. Proteins and enzymes with unique properties from fish and crustaceans are subject to the same limitations and in addition genetically engineered micro-organisms reduce production costs of these specialised proteins significantly by replicating enzymes and amino acids sequences and chemically synthesising these proteins. Hydrolysates from different fish species have been claimed to possess a range of health promoting properties with most attention given to antihypertensive peptides. The bioactive peptides derived from fish are mainly made from fillets although some of these products have been identified in fish by-products. Once again the market for marine derived bio-active peptides is hampered by approval for health claims by authorities and the presence of many competitive existing bio-active peptides on the market. Astaxanthin, a pigment extracted from crustacean processing waste, is used commercially as a native form in aquaculture feed for salmonid and crustacean species. However, it is estimated that more than 95% of the global astaxanthin supply is made synthetically at comparative low cost. In conclusion According to the authors of this paper, Ragnar L Olsen, Jogeir Toppe and Iddya Karunasagar, the most realistic uses of marine by-products are as food or feed ingredients. However, to upgrade by-products as food co-products implementation of quality systems such as HAACP or GMP is necessary which can be problematic in some processing facilities. The price and demand for fishmeal and fish oil has increased due to limited supply as well as growth in aquaculture industry which led to a change from former low value products to desirable specialised products. Low cost technologies such as silage production contribute toward the handling of by-product volumes that is too small for traditional fishmeal and oil processing. Apart from omega-3 fatty acids, the isolation of high value bioactive compounds is generally not feasible due to high cost of isolating specific components, lack of existing markets, too small amounts of high quality by-products available on a regular basis and the challenges connected with providing the documentation required for a potential nutraceutical product. In addition, chemical synthesis or genetically modified microorganisms can produce copies of bio-active components at a very reasonable and competitive cost.