Biomass recovery from herring brines: Exploring quality and functionality of protein and n-3 polyunsaturated fatty acids

Protein-enriched biomasses recovered from herring brines using dissolved air flotation (DAF) at native or low pH were studied in terms of nutrients, volatile compounds, emulsion properties, foaming properties and protein structure. Dried biomasses from native or acidified 3 % pre-salting brine (SB and SB-A) and spice brine (SP and SP-A) contained 69-72 % and 20-31 % protein, respectively; 7.8-10.2 % and 9-18 % lipids, respectively, and 4.4-7.5 % and 33-36 % ash, respectively. Of total fatty acids, up to 44 % were long-chain monounsaturated fatty acids (LC MUFA) and 17 % LC n-3 polyunsaturated fatty acids (PUFA). Both emulsion activity index (EAI) and foaming capacity (FC) were higher for SP/SP-A than SB/SB-A. In both cases, there was a minimum at pH 5. The findings suggest that currently wasted herring brine side streams hold promise for production of sustainable, functional protein ingredients which can provide both flavor and nutrients.