Urea-PAGE patterns of PDO Évora cheese manufactured with Cynara cardunculus L. ecotypes

Abstract

Some Portuguese and Spanish ewe’s cheese are made with the aqueous extracts of Cynara cardunculus L. dried flowers. Évora cheese is a Portuguese PDO cheese which is characterized with a semi-hard or hard consistency, a light yellowed colour, by few or no hole and by an intense flavour. It is obtained by draining slowly the curd, after the coagulation of raw ewe’s milk with the action of C. cardunculus vegetable coagulant. The renewed interest in the enzymes of this extracts prompted to the investigation of its proteolytic effect in Évora cheese. Urea-PAGE of the casein fraction was done to enable the evaluation of the extent of proteolysis of Évora cheese made with three C. cardunculus ecotypes (Cynara 1, Cynara 2, Cynara 3), compared with a commercial animal rennet (Animal) after 1, 7, 14, 21, 35, 49 and 60 days of ripening and therefore to establish the pattern of the casein fractions degradation. The results showed a higher protein degradation of cheeses made with vegetable coagulant than cheeses made with animal coagulant. Up to 35 days of ripening there was an increase of the casein degradation rate, remaining relatively constant until the end of maturation. After 63 days of ripening, αS-caseins (54.90%) were more degraded than β-caseins (37.27%) in cheeses made with C. cardunculus ecotypes.