Influence of milk-clotting enzyme concentration on the alpha(S1)-casein hydrolysis during soft cheeses ripening

We studied the influence of the dose of milk-clotting enzyme on alpha (s1)- CN degradation, soluble nitrogen production, and sensory profile for an Arg entinean soft cheese: Cremoso Argentino. Five different types of cheeses we re produced: 1) control cheeses with normal technology, 2) cheeses with ina ctivated milk-clotting enzyme, 3) cheeses with inactivated milk-clotting en zyme, without starter (acidified with glucono delta lactone), 4) cheeses wi th a half dose of milk-clotting enzyme, and 5) cheeses with a double dose o f milk-clotting enzyme. Proteolysis was assessed by isoelectric focusing el ectrophoresis of the insoluble fraction at pH 4.6, followed by densitometri c quantification. Soluble nitrogen at pH 4.6, expressed as a percentage of total nitrogen and defined as ripening index was also performed. A sensoria l panel evaluated the cheeses at the end of ripening. The hydrolysis level of alpha (s1)-CN depended on the milk-clotting enzyme dose used in cheese m aking. Cheeses without active coagulant did not show degradation at the end of ripening, while cheeses with half and whole doses showed proportional d egradations to coagulant dose. Cheese with a double dose of coagulant did n ot show higher alpha (s1)-CN hydrolysis than normal cheese. No difference w as found between cheeses with and without microbiological starter, indicati ng that the selected culture, composed of thermophilic strains, was unable to attack the whole casein. A high linear correlation was found between rip ening index and the relation %alpha s1-I/alpha s1-I+alpha s1. Sensorial characteristics of cheeses agree with objective analysis. Cheeses without active coagulant were hard and crumbly, while cheeses with normal dose were soft and creamy.