Comparison of the effects of high pressure homogenization and high pressure processing on the enzyme activity and antimicrobial profile of lysozyme

Abstract

The effects of high pressure homogenization (HPH, < 190 MPa) and high pressure processing (HPP, < 600 MPa) on hen egg white lysozyme muramidase and antimicrobial activities were assessed. The results showed enzyme activation under mild process conditions (< 120 MPa for HPH and < 400 MPa for HPP, both at 20 °C) and mostly for activity measured at non-optimum pH and temperature. When processes were carried out at 50 °C, lower activation were observed (< 18% for HPH and < 13% for HPP), possibly indicating that processes at 50 °C delivered enough energy to promote undesirable unfolding on lysozyme. HPH induced a greater increase in muramidase activity (29%) than HPP (17%), but this not reflected the antimicrobial performance of the processed lysozyme, since only HPP reduced the minimum inhibitory concentration of the lysozyme against Bacillus cereus (50%) and Geobacillus stearothermophilus (66%). The results highlighted that each process changed differently the lysozyme muramidase and antimicrobial activity