Production of antioxidant hydrolysate from bovine casein using immobilized Penicillium aurantiogriseum protease on magnetic nanoparticles

Peptides with bioactive properties can be released from the precursor proteins during food processing or digestion, and act as antioxidative compounds. Although, it has been proven that hydrolysate exerts higher antioxidant activity than purified peptides. The process of enzyme immobilization proved to be more practical and advantageous for catalysis than using free enzyme. The aim of this study was to use a protease produced by Penicillium aurantiogriseum immobilized on polianilin-coated magnetic nanoparticles, for bovine casein hydrolysis and to evaluate the hydrolysate antioxidant properties. The 60-80% saline fraction of crude extract was used in immobilization. Commercial casein from bovine milk 1% (w/v) was hydrolyzed by 10 mg/mL of immobilized protease. The casein hydrolysates were used in ABTS and H2O2 scavenging activity assays, where Trolox was used as standard. In the ABTS scavenging assay, the hydrolysate (1% w/v) revealed a 1341 μmol of Trolox equivalent activity and in the hydrogen peroxide scavenging assay, the hydrolysate (using 0.1% w/v) presented a 547.82 μmol of Trolox equivalent activity. In both assays the hydrolysates presented a more than 2.5 times greater activity than non-hydrolyzed casein, which validates the process capacity of developing casein derived natural antioxidant ingredients with potential for functional foods.