Characterization of liposomes and their effect on the properties of Cheddar cheese during ripening

Abstract

This study was undertaken to observe the location and structure of liposomes in the cheese matrix and to identify their effect on the characteristics of Cheddar cheese during ripening. Com- position, proteolysis, microstructure and texture of Cheddar cheeses treated with either empty lipo- somes or liposomes containing cell-free extracts of Lactobacillus casei ssp. pseudoplantarum were ana- Iysed during two months of ripening. Results were compared with control Cheddar cheeses. Observations on cheese microstructure showed that sorne liposomes were included in the casein matrix, but most vesicles were located in areas close to fat globules and appeared destabilized as early as the first day after manufacture, inducing sorne changes in the cheese microstructure. The pre- sence of liposomes greatly increased the moisture of cheeses, modified the microstructure and the rheo- logical characteristics of ripened cheese. Cheeses containing liposomes were softer, less cohesive and elastic 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 extracts. HPLC-analysis confirmed intensive peptidolysis between one and two months of ripe- ning. © InralElsevier, Paris liposome / cheese / microstructure / ripening