Effect of starter cultures on the physico-chemical and biochemical features in ewe cheese made with extracts from flowers of Cynara cardunculus L

Abstract

The effect of starter cultures on the physico-chemical and biochemical features of Los Pedroches cheese made by using Cynara Cardunculus L extracts as vegetable coagulant was assessed. Specimens of cheese containing no starter (vats A and C) and others to which a lactic acid starter was added (vats B and D) were stored either under typical farmhouse ripening conditions (vats A and B) or in a controlled chamber at 14 degrees C and 80% relative humidity (vats C and D) for 90 days. The addition of starter cultures and the ripening conditions where found to have no appreciable effect on the moisture, fat, protein, ash, NaCl, Ca and P contents of the cheese, nor on its water activity; however, it resulted in increased lactic acid contents and lower pH values relative to control specimens throughout ripening. The protein breakdown of the cheeses was assessed in terms of soluble nitrogen, nonprotein nitrogen, aminoacid nitrogen, ammonia nitrogen, soluble tyrosine and tryptophan, and urea-PAGE. Proteolysis was generally more marked and rapid in cheese containing the lactic starter, the NPN, NH3-N and soluble Tyr and Trp contents of which were significantly higher than those of the cheese obtained with no starter. The PAGE technique revealed no appreciable differences between the four cheese batches studied; however, it showed the cheese to be more resistant to beta-CN hydrolysis than to alpha(s)-CN hydrolysis. In general, the flavour and aroma scores were higher in batches obtained with starter cultures and ripened under controlled conditions. (C) 1999 Society of Chemical Industry.