Modelling the relationship between the Évora, Serpa and Nisa cheese casein fractions and their degradation products using linear regression analysis

Abstract

Some Portuguese and Spanish ewe’s cheese are made with the aqueous extracts of Cynara cardunculus L. dried flowers. The renewed interest in vegetal coagulant prompted to the investigation of its proteolytic effect. Different Cynara cardunculus L. populations (Cynara 1, Cynara 2 and Cynara 3) were used in the cheesemaking of PDO Évora, Serpa and Nisa cheeses. Cheese samples were analysed by urea-PAGE to identify the casein fractions, enabling the evaluation of the extent of proteolysis. The casein fractions obtained where separated in four areas: β-caseins, αS-caseins and their degradation products, γ-caseins and pre-αS-caseins (CN), respectively. The aim of this work was to identify the relation of the caseins fractions and their degradation products through a simple linear regression method (LRM), regarding the effect of Cynara cardunculus L. coagulant, and the matrix of three PDO cheeses, during ripening process. Results showed significative correlations between the predictors variables (αs- and β-CN) and the responses variables (pre-αS-CN and γ-CN) in the three cheeses. Coefficients of determination (R2) between αs-CN and pre-αS-CN in all cheeses was superior to 0.80, while the R2 between βCN and γ-CN was less than 0.80. These results suggest that αs-CN can be a good predictor of preαS-CN, providing viable information regarding the proteolysis process in DOP Évora, Serpa and Nisa cheeses. The presen