Inactivation of Lactobacillus brevis in beer utilizing a combination of high-pressure homogenization and lysozyme treatment

Abstract

Inactivation of Lactobacillus brevis in beer by high-pressure homogenization (HPH) and lysozyme addition was evaluated. The minimum inhibitory concentration of lysozyme against L. brevis was determined and found to be 100 mg.L-1. The effects of the homogenization process on lysozyme antimicrobial activity and muramidase activity, and the microbial reduction promoted by HPH, and by HPH associated with lysozyme, were evaluated. A significant reduction in lysozyme muramidase activity was observed under 250 MPa, however, no reduction in antimicrobial activity was observed after homogenization up to 300 MPa. The HPH at 100, 140 and 150 MPa promoted 1, 3 and 6 decimal reductions in L. brevis microbial counts, respectively. The HPH and lysozyme association had an additive effect on microbial inactivation, immediately after homogenization, and the lysozyme remained active during 10 days of storage, increasing the inactivation of L. brevis up to a 6 decimal reduction. Therefore, the application of lysozyme with HPH has the potential to reduce the level of pressure required for beer processing, improving the economic costs when utilizing HPH. © 2011 The Institute of Brewing & Distilling.