Influence of different amounts of vegetable coagulant from cardoon Cynara cardunculus and calf rennet on the proteolysis and sensory characteristics of cheeses made with sheep milk

Different amounts of powdered vegetable coagulant (PVC) obtained from Cynara cardunculus (normal amount = PVC; double the normal amount = 2PVC) were compared with calf rennet in cheese made from sheep milk, by determining different chemical, biochemical, and sensory characteristics throughout of 6 months of ripening. For most of the chemical parameters studied, no differences were observed between the coagulants assayed. However, significantly higher (p<0.05) levels of casein hydrolysis, measured as soluble nitrogen (SN), non-protein nitrogen (NPN), amino acid nitrogen (AAN) and ammonia-nitrogen (N.NH3 were observed after 2 days of ripening in cheeses produced with 2PVC compared with those made with normal amount of PVC. Furthermore, only the levels of SN and NPN were significantly higher (p<0.05) in cheeses produced with PVC than those obtained with calf rennet. The main sensory characteristics were enhanced (p<0.05) in cheeses obtained with vegetable coagulant in comparison to those made with calf rennet. The bitter taste of cheeses produced with 2PVC was not significantly stronger (p>0.05) than in those produced with a normal amount of vegetable coagulant (PVC). The increased proteolytic activity of the vegetable enzymes enables manufacturers to produce fully ripened cheeses (especially when the amount of the vegetable coagulant is doubled) with all the genuine end-product organoleptic characteristics approximately 3 months earlier than if calf rennet is used. (C) 2007 Elsevier Ltd. All rights reserved.