Linking casein hydrolysis by chymosin and plasmin to the rheological and textural properties of model cheese

Abstract

The texture of cheese highly depends on the structure of its network, which develops during ripening due to the enzymatic degradation of caseins. However, the influence of the hydrolysis of individual casein fractions (αs1-and β-CN) on specific textural properties remains unclear. In this study, we aimed to link the breakdown of individual casein fractions by chymosin and plasmin to different rheological and textural properties used to characterize cheese texture. Model cheeses with two plasmin levels (active and inactive) and three chymosin levels (20, 50, and 80 IMCU/kg milk) were prepared.Our results showed that the hydrolysis of αs1-and β-CN by chymosin and plasmin played different roles in the rheological and textural properties of the samples. The hydrolysis of αs1-CN predominantly led to a decrease in G′ and Young's modulus, parameters related to the strength of the protein network. The hydrolysis of β-CN was more associated with changes in critical strain, resilience and cohesion, which were linked to rearrangements within the protein network resulting from hydrophobic interactions among hydrolyzed products. Hardness_40% (stress at a strain of 40%) was related to hydrolysis of both αs1-CN and β-CN, although the effect of αs1-CN degradation seemed more pronounced. The obtained knowledge offers new insights into the mechanisms behind cheese texture development.