Yield, physicochemical, and antioxidant properties of Atlantic salmon visceral hydrolysate: Comparison of lactic acid bacterial fermentation with Flavourzyme proteolysis and formic acid treatment

This study compares a cost-effective microbial method, involving lactic acid (LA) fermentation, with the conventional formic acid (FA) treatment and Flavourzyme (FL) enzymatic hydrolysis for valorizing Atlantic salmon processing waste (Viscera). LA and FA processing approaches relied on production (LA) or addition (FA) of organic acids to lower the pH and activate the inherent proteases in these tissues, whereas FL processing was carried out at the optimum conditions for Flavourzyme (37 degrees C, pH 7.0). Highest protein hydrolysate fraction recovery (approximate to 57%) was seen in LA fermentation, while FA processing resulted in the highest protein levels (approximate to 87%) in the recovered hydrolysate fraction and lowest residual fraction (approximate to 4%). In general, FL processing demonstrated higher Fe(II) chelation (73%) and ferric reducing capacity (27 mM glutathione equivalent) whereas LA-hydrolysates showed enhanced sacrificial antioxidant properties. Findings from this study would have implications on the application and production of salmon-based protein hydrolysates, especially, from the perspective of their functionality. Practical applicationsPeptides derived from natural sources such as fish products have been extensively reported to exert antioxidant activity that mitigates oxidative stress and providing beneficial effects to human health as well as food storage. Several sources of proteins are being explored for the production of biologically active peptides. Utilizing by-product streams such as fish processing waste is especially attractive as these are cheaper and rich sources of protein. Therefore, utilizing marine bioprocessing waste for the production food-grade protein hydrolysates is promising, especially in Atlantic Canada.