Co-Extraction of Gelatin and Lipids from Yellowfin Tuna (T hunnus albacares ) Skins: Physicochemical Characterization, Process Simulation and Economic Analysis

Abstract

Gelatin and lipids were co-extracted, on a laboratory scale, from yellowfin tuna (Thunnus albacares) skins with estimated yields of 11.67 and 11.65 g component/100 g fish skins, respectively. Fish gelatin gave solutions that were odorless with light yellowish hue similar to commercial preparations. Furthermore, fish gelatin exhibited high gel strength (280 g) and melting point (27.9C) and relatively high viscosity (4.92 cP). Lipids recovered from yellowfin tuna skins contained significant amounts of long-chain n-3 polyunsaturated fatty acids, with eicosapentaenoic and docosahexaenoic acid representing ∼19% of the total fatty acids. In a follow-up study, the economic feasibility of co-extracting gelatin and lipids from yellowfin tuna skins was investigated and the whole process was simulated and presented in the form of a flow chart using SuperPro Designer. The economic analysis showed that the prospect of processing yellowfin tuna skins for gelatin and lipids production on a large commercial scale is highly attractive. Practical Applications Yellowfin tuna (Thunnus albacares) is a commercially important fish species that is processed into various kinds of products (e.g., canned tuna chunks, frozen tuna steaks and smoked tuna fillets). As a result of the technologies employed, large amounts of by-products are formed, which can account for as much as 50% of the initial fish weight. At present, the by-products generated by the tuna processing industry in Greece are trucked frozen to farms for use as animal feed or dumped into landfills, despite the presence of highly functional and healthy ingredients, such as collagen and fish oil. Utilization of these by-products, especially of collagen-rich fish skins for gelatin and lipids production, will not only increase their commercial value but will also help better utilize our natural resources.