Quantification of biomolecules in herring (Clupea harengus) industry processing waters and their recovery using electroflocculation and ultrafiltration

Four types of herring industry processing waters; refrigerated sea water (RSW), storage water (SW), processing water from cutting (PW) and pre-salting brines (SB) were subjected to chemical characterization and biomolecule recovery using electroflocculation (EF) and ultrafiltration (UF). The highest protein and fatty acid content were found in SB's, up to 12.7 ± 0.3 and 2.5 ± 0.1 g L-1, respectively.

Long chain n-3 polyunsaturated fatty acids represented up to 44.5% of total fatty acids. In all samples, leucine and glutamic acid/glutamine were the dominating amino acids while calcium and magnesium were the dominating trace elements. EF plus UF in series recovered up to 80% proteins and fatty acids from SB's and reduced chemical oxygen demand by 70%.

Foaming and emulsifying properties of biomolecules were improved or unaffected by EF/UF treatment. To conclude, large amounts of biomass are currently lost per ton of processed herring, e.g. ∼9.2 kg proteins and ∼4.1 kg fatty acids; EF/UF represents a promising way of turning such losses to a potential income.