Abstract
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.