Accelerated Cheddar cheese ripening with encapsulated proteinases

This work was undertaken to study the impact of bacterial and fungal proteinases encapsulated in liposomes on proteolysis and organoleptic properties of Cheddar cheese during ripening. Bacterial and fungal proteinases were encapsulated in liposomes with trapping efficiencies of 31.9 and 33.0%, respectively. The encapsulated bacterial proteinase was incorporated into Cheddar-cheese milk in order to reach enzyme concentrations of 5 x 10(-6) (B-1), 1 x 10(-5) (B-2) and 2 x 10(-5) (B-3) AU g(-1) cheese curd, while encapsulated fungal proteinase was added in order to reach enzyme concentrations of 1 x 10(-6) (F-1), 2 x 10(-6) (F-2) and 4 x 10(-6) (F-3) AU g(-1) cheese curd. Experimental cheeses showed slightly higher moisture content but lower protein content when compared to control cheeses. Rheological measurements revealed that experimental cheeses were slightly less firm but more brittle as compared to control cheeses. Proteolysis and texture development of experimental cheeses were faster than control cheeses. As observed by transmission-electron microscopy, liposome-treated cheeses exhibited less compact microstructure and liposomes were essentially located at the fat-casein interface. The elution patterns obtained from size-exclusion chromatography revealed that the accumulation of bitter and astringent peptides was higher in experimental cheeses than in control cheeses depending on the type and concentration of added enzyme. After 3 months ripening, the organoleptic properties of cheeses were markedly improved and no bitter off-flavour was detected among treatments except cheeses subjected to treatments B-3 and F-3. The present study showed that micro-encapsulated enzymes can be successfully used to accelerate cheese ripening and to avoid drawbacks resulting from the use of free enzymes. It was also concluded that the addition of encapsulated bacterial proteinase (up to 1 x 10(-5) AU g(-1) cheese curd) or encapsulated fungal proteinase (up to 2 x 10-6 AU g(-1) cheese curd) could be recommended to accelerate the flavour and texture development of Cheddar cheese.