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

Abstract

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 (European Union) 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 Northwest Coast of the Iberian Peninsula. Boarfish protein hydrolysates (BPHs) 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 APPLICATIONSThis manuscript addresses the problem of underutilized marine biomass: discards and byproducts from boarfish (Capros aper) and small-spotted catshark (Scyliorhinus canicula). These species are frequently discarded or used for lowvalue 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.

Characterization and potential strategies for the valorisation of the Southwest Atlantic butterfish (Stromateus brasiliensis)

“…Stromateus brasiliensis is a fish with a small head and fins, so the yield of the edible portion represents 55% of the total fish weight when manually separated. This value is similar to other commercial fish, with fish flesh percentages of approximately 40-60 (Blanco et al 2015). From this result, it is expected that direct human consumption of S. brasiliensis is feasible.…”

“…The pH and temperature were controlled with a glass-combined electrode connected to a Metrohm Titrando 902 system (Metrohm, Switzerland) operated by a PC (software Tiamo 2.3). Alcalase (Alcalase Novozymes A/S, Spain) was used for hydrolysis, and triplicates for each sample were analysed according to Blanco et al (2015). Portions of 15 g of thawed mince muscle were suspended in 75 ml of water (1:5 w/v).…”

“…Through controlled enzymatic hydrolysis, it is possible to obtain valuable small peptides that are a source of good-quality protein that can be used in aqua feed and animal feed (Martínez-Alvarez et al 2015) or to increase protein content in products for human consumption, such as cheese sticks and biscuits (Egerton et al 2018). Sardina pilchardus, Trachurus mediterraneus, Pagellus acarne, Boops boops, Scyliorhinus canicula, Micromesistius poutassou and Capros aper are some of the species previously employed to obtain fish protein hydrolysates that have good nutritional composition, amino acid profile, and antioxidant activities (Chalamaiah et al 2012;Blanco et al 2015;Pérez-Gálvez et al 2015).…”

Multifunctional and biomimetic fish collagen/bioactive glass nanofibers: fabrication, antibacterial activity and inducing skin regeneration in vitro and in vivo

“…19,20 It is possible to use fish discards to isolate collagen, which is further used in various biomedical fields, such as in wound dressing. 21 However, effective wound dressings should have suitable tensile strength, a certain degree of antibacterial activity, as well as the ability to promote skin regeneration early.…”

“…Briefly, 4.0 g P123 (triblock copolymer of polyethylene oxide-polypropylene oxide-polyethylene oxide, EO 20 PO 70 EO 20 ), 6.7 g tetraethyl orthosilicate, 1.4 g Ca(NO 3 ) 2 ⋅4H 2 O, 0.73 g triethyl phosphate and 1.0 g 0.5 M HCl were dissolved in 60 g ethanol (Si/Ca/P =80:15:5 mole ratio) and stirred at room temperature for 1 day to form BG precursor solution.…”