Effects of high pressure homogenization on the activity of lysozyme and lactoferrin against Listeria monocytogenes

The effects of high pressure homogenization treatment at 100 MPa (HPH), in comparison to different heat treatments, 70 °C for 30 s, 70 °C for 5 min or 100 °C for 5 min, on the activity of lysozyme and lactoferrin, were studied. The antimicrobial activities of lysozyme and lactoferrin were tested on Listeria monocytogenes inoculated in milk or cultural medium. The results indicated that antimicrobial activities of lactoferrin and lysozyme were enhanced and/or accelerated by HPH treatment. Particularly, the highest immediate inactivation values were recorded when L. monocytogenes cells were added to HPH-treated lactoferrin, processed simultaneously or separately with the target microorganism. Although to a lesser extent than HPH treatment the heat treatments applied also were able to increase the antimicrobial activity of lysozyme.