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Dimitra Marinou

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In the fish industry up to 70% of the entire fish ends up as side-streams. In order to reduce the amount of side-streams and meet the demand of the growing population, a higher utilization degree of the fish is needed. The aim of this study was to use cod backbone for enzymatic production of bioactive hydrolysates with antioxidative and antimicrobial properties. Three different enzymes were applied (Alcalase, Neutrase and Protamex) and hydrolysis was carried out for ½ - 6h within the enzyme’s optima for pH and temperature. Alcalase treated samples had the highest protein extracted yield (PEY) followed by Protamex treated samples and lowest PEY was obtained with Neutrase. No correlation was observed between PEY and degree of hydrolysis (DH). All hydrolysates had antioxidant activities measured by radical scavenging and iron chelation in vitro assays. For radical scavenging activity, Protamex treated hydrolysate showed lowest IC50 and had a molecular weight < 10 kDa. Whereas for iron chelation activity, the control samples (no enzyme added, but heat treated) showed similar or lower IC50 with molecular weights of 200 – 10 kDa. Amino acid composition measured on selected hydrolysates suggested that not only composition of amino acid, also but sequence and size influence the properties. None of the hydrolysates showed antimicrobial activity measured by the Minimum Inhibitory and disk diffusion assays. In summary, the results showed that protein with antioxidant activity can be extracted from the cod backbone and make it possible to use the side-streams generated in the fish industry.