Animal-origin food waste hydrolyzates and its use as aquaculture feed ingredient

Food waste represents one of the most significant challenges facing the current agri-food system, with significant economic, environmental and social implications. Within this context, the meat sector stands out for its high generation of by-products that represents a relevant environmental problem, although, on the other hand, such by-products constitute a potential source of high added-value compounds, especially due to their protein, amino acids, and bioactive peptides content. At the same time, the growth of the aquaculture sector demands new functional, sustainable and low-cost ingredients for the formulation of aquaculture feed, which opens up a new advantage for the revalorization of animal by-products. This chapter reviews the generation and uses of slaughterhouse farm animal by-products such as viscera, blood, bones and other residues, mainly through the hydrolysis of their proteins. Enzymatic hydrolysis is proposed as a sustainable and efficient alternative for the upcycling of these by-products, obtaining hydrolyzates with interesting nutritional properties for their incorporation as new functional ingredients in aquaculture feed improving not only the sustainability of the aquaculture sector, but also contributing to circular economy in the meat sector.