Marine Processing Proteinaceous By-Products: A Source of Biofunctional Food Ingredients

Large quantities of by-products from the fish and shellfish processing industries are generated annually. These consist of heads, bones, viscera, gills, muscle, belly flaps, and skin of different fish species, along with shells and byssus from shellfish, in addition to catch below the standard for trade. Given the rapid increase in aquaculture in the last decade, it is expected that 99.33 million tons of by-products will be generated annually by 2022. Currently, the by-products are discarded or used mainly as fertilizer or animal feed or are further processed for fish oil extraction. However, it is becoming more evident that marine processing by-products are rich reservoirs of structurally diverse biofunctional nitrogenous components, such as proteins, peptides, and amino acids. They can contain significant levels of high-quality protein (10-23% w/w) and may act as substrates for the generation of bioactive peptides. Enzymatic hydrolysis is used for modification of food proteins to improve their physicochemical, bio- and techno-functional as well as sensory properties. With the rapid increase in incidences of metabolic diseases, such as diabetes, hypertension, and dyslipidemia, an opportunity exists to identify new marine-derived bioactive components targeted for the prevention and management of these conditions. Based on published studies, marine by-products from the fish and shellfish industry may have potential as value-added sources of antioxidant, antidiabetic, cardioprotective, and other biofunctional food ingredients.