A new approach to lysozyme in cheese manufacture: boosting key enzyme activities in the ripening process

The rational use of lactobacilli and lysozyme (LZ) could be a simple strategy for boosting key enzyme activities during cheese ripening. This study investigated the effect of the application of LZ on the cell envelopes and metabolic potential of two strains of mesophilic lactobacilli: <i>Lactiplantibacillus plantarum</i> 29 (L29) and <i>Lacticaseibacillus rhamnosus</i> 77 (L77). An in vitro study of LZ-sensitivity was carried out on the two strains. In L29 (only), the results of turbidity, culturability and physiological profile as well as fluorescence microscopy images and scanning electron micrographs confirmed a high-level of sensitivity to LZ. Therefore, L29 alone or in combination with LZ as well as a cell-free extract of L29 were used as ripening agents in the manufacture of a mature cheese. The release of peptidases in the cheese matrix by the lysis of L29 <i>in situ</i> was validated and associated with positive effects on the cheese quality, especially the increase of hydrophilic peptide levels.