Hydrolysis as a Valorization Strategy for Unused Marine Food Biomass: Boarfish and Small‐Spotted Catshark Discards and By‐Products

Discarded fish represent a serious obstacle to the sustainability of fisheries. The main outcome of analyses on the impact of discarding has been the implementation of a zero‐discard policy in EU ( E uropean U nion) waters. One concern in implementing this policy is finding alternatives to help fishers alleviate the costs of nondiscarding. Boarfish and small‐spotted catshark are frequently discarded along the N orthwest C oast of the I berian P eninsula. Boarfish protein hydrolysates ( BPH s) were prepared using a pancreas crude extract ( PCE ) from small‐spotted catshark and compared with those prepared with commercial proteases. BPH prepared with PCE and commercial trypsin contained more protein than alcalase hydrolysates; however, the latter showed greater solubility. Emulsifying and foaming properties were higher when using bovine trypsin, followed by PCE . Antioxidant activities were similar. Fish by‐products or fish with low flesh yields, usually wasted, contain valuable compounds that could be employed to obtain value‐added products such as fish protein hydrolysates. Practical Applications This manuscript addresses the problem of underutilized marine biomass: discards and byproducts from boarfish ( C apros aper) and small‐spotted catshark ( S cyliorhinus canicula ). These species are frequently discarded or used for low‐value processes. One of the main challenges that face the objective of bycatch and discard reduction is finding alternatives that help the fishing industry overcome the costs associated with landing captures. Fish protein hydrolysates have many different potential applications and this manuscript suggests a selection of them, such as utilization as a food or feed ingredient.