Lipid Oxidation in Innovative Protein Enriched Products from Cod- salmon and Herring Backbones During Ice and Frozen Storage.

Other conference contribution, 2021

The demand for high value proteins is increasing every year due e.g., to population growth and a diet shift to more proteins driven e.g., by an aging population. Co-products emerging in fish filleting operations contain significant amounts of muscle rich in high value protein, which could be better used in food production to cover the growing protein demand. However, applying value-adding techniques to fish filleting co-products is rendered difficult due to their high susceptibility to lipid oxidation. In the first part of this study, seven components/formulas (water-soluble rosemary extract (RE-A), oil-soluble rosemary extract (RE-B), isoascorbic acid (IAA), esculetin, α-tocopherol (α-TOC) or and two rosemary-containing commercial mixtures; Duralox MANC-213 (MANC) and EVESA-C5 (EVESA)) were directly added into minced herring co-products to screen their ability to prevent lipid oxidation during ice storage. The order by which the seven compounds delayed lipid oxidation was as follows: RE-B (0.05%) = MANC (0.5%) = EVESA (0.5%) > IAA (0.5%) > RE-A (0.2%) > esculetin (0.09%) > α-TOC (0.02%). The two most promising candidates based on both cost and efficiency were used in a second trial where herring co-products were dipped in antioxidant-containing solutions prior to subsequent cold-storage for 12 days in a minced or intact form. The effect of re-cycling the antioxidant solutions was also studied, and both PV and TBARS were analyzed. Dipping of the co-products with a 0.2% RE-B solution with and without 0.5% IAA added remarkably increased the oxidation lag phase from < 1 day to >12 days during subsequent cold storage in minced or intact form. Even after re-use of the dipping solution up to 10 times, lipid oxidation was completely inhibited. The presented dipping strategies could hereby facilitate more diversified end-use of herring co-products from current fish meal to high-quality minces, protein isolates or oils for the food industry.