Valorization of fisheries by-products via enzymatic protein hydrolysis: A review of operating conditions, process design, and future trends

Abstract

Fisheries by-products constitute large waste streams, despite containing protein, lipids, and other valuable compounds. The enzymatic protein hydrolysis process has been established as a means of effectively retrieving these products, though there has been little study to date on the impact of process operating conditions, pre-treatments, and process design on product quality. This review studies the impact of operating conditions relevant to the process, as well as the important parameters governing design and scale-up of the process. Findings indicate pre-treatments such as defatting, while common in literature, can limit the degree of hydrolysis of protein hydrolysates, while also conferring negative environmental impacts. Process conditions, such as temperature, pH, water ratios, and enzyme dose are typically established at lab scale, and can be at a disconnect with pilot and industrial scale studies. Furthermore, the water quality and pH control methods applied at lab scale are difficult to achieve at commercial scale. Current innovations involving endogenous fish enzymes and Enzyme Membrane Reactors may improve feasibility of this process in future, though these require more work. Enzyme hydrolysis is a promising technology for valorizing fisheries and other proteinaceous by-products and could see enhanced use in industry from further study on kinetics and scale-up.