No abstract

Lactoperoxidase (LPS), purified directly from bovine rennet whey by Toyopearl-SP cation-exchange chromatography and lyophilized by using dextran as supporting material, maintained almost 70 and 60% of its activity after almost 2 and 5 months storage at À18°C, respectively. Incorporation of the prepared LPS into alginate films between 0.08 and 0.69 mg/cm 2 (516-4325 U/cm 2 ) caused the immobilization of most of the enzyme and gave films with LPS activity between 0.05 and 2.8 U/cm 2 , determined in the presence of 8 lM H 2 O 2 . Between 2 and 24 lM H 2 O 2 concentrations, a two-fold increase in H 2 O 2 concentration caused 1.5-2.5-fold increase in LPS activity of films incorporated with 0.24-0.28 mg/cm 2 (1200 U/cm 2 ) LPS. The Q 10 and E a of immobilized enzyme activity between 4 and 16°C were 1.69 and 34.6 kJ/mol, respectively. However, in the 16-30°C range, the temperature change had almost no effect on LPS activity of films. The optimal activity of immobilized LPS was observed at pH 6.0, but the enzyme maintained 30-85% of its activity between pH 3.0 and 7.0. The immobilized LPS also had a high stability between pH 4.0 and 6.0. The results of this study showed the good potential of LPSincorporated alginate films in forming a natural antimicrobial mechanism in different foods.