Effects of plasmin on camel and bovine model cheeses: Protein degradation, texture, and rheology

This study investigated the effects of plasmin addition on the physicochemical, textural, and rheological properties throughout the ripening process of cheeses made of camel and bovine milk. Model cheeses were produced with varying plasmin concentrations (0, 0.15, 0.3, and 0.6 U/100 mL milk) to assess changes in physicochemical attributes, casein hydrolysis, hardness, and rheological behavior. Three-way ANOVA demonstrated that the type of milk, plasmin level, ripening duration, and their interactions significantly influenced titratable acidity (%), pH, concentrations of free amino groups, and hardness (p < 0.05). Urea-PAGE analysis revealed changes in CM and BM cheeses during storage, most notably a reduction in the intensity of the β-casein band indicating progressive proteolysis. Ripening resulted in elevated concentrations of free amino groups in both camel and bovine milk cheeses (p < 0.05). The proteolysis of casein during ripening, subsequently leads to increased water retention, which contributes to softer cheese and reduction in both G´ and G´´ values over time.