CHARACTERIZATION OF LIPOSOMES AND THEIR EFFECT ON THE PROPERTIES OF CHEDDAR CHEESE DURING RIPENING

This study was undertaken to observe the location and structure of lip osomes in the cheese matrix and to identify their effect on the charac teristics of Cheddar cheese during ripening. Composition, proteolysis, microstructure and texture of Cheddar cheeses treated with either emp ty liposomes or liposomes containing cell-free extracts of Lactobacill us casei ssp. pseudoplantarum were analysed during two months of ripen ing. Results were compared with control Cheddar cheeses. Observations on cheese microstructure showed that some liposomes were included in t he casein matrix, but most vesicles were located in areas close to fat globules and appeared destabilized as early as the first day after ma nufacture, inducing some changes in the cheese microstructure. The pre sence of liposomes greatly increased the moisture of cheeses, modified the microstructure and the rheological characteristics of ripened che ese. Cheeses containing liposomes were softer, less cohesive and elast ic and more brittle than control cheeses. After two weeks of ripening and until the end of the study, proteolysis, particularly peptidolysis , was higher in cheeses treated with Liposomes containing cell-free ex tracts. HPLC-analysis confirmed intensive peptidolysis between one and two months of ripening. (R)Inra/Elsevier, Paris.