Algerian cardoon flowers express a large spectrum of coagulant enzymes with potential applications in cheesemaking

Proteases from flowers of Algerian cultivated and wild cardoons were purified, characterised and compared with those purified from flowers of a Portuguese variety. Three cardosins (A0, A and B) were obtained from each variety. All of them were dimeric and comprised heavy and light chain. Cardosins from Algerian varieties presented higher molecular masses and were less glycosylated than their Portuguese counterparts. Milk coagulation and curd yield parameters revealed a large difference between cardosins A0, A and B and among the same cardosin from different origins. The enzymatic specificity of cardosins, studied against β-chain of oxidised insulin and κ-casein, showed no prevalent effect of varieties. However, compared with cardosins A0 and A, cardosin B was more proteolytic and led to more complex digestion profiles. The present study reports the first description of the diversity of cardosins in Algerian cardoon flowers and sustains their potential use as milk coagulants for cheesemaking.