Relation between pH, degree of proteolysis and consistency in soft cheeses
Résumé
Hard and acid body is a common texture defect in soft cheeses like Italian Crescenza and Cremoso, a popular Argentine soft cheese. It results from poor texture development during maturation, such that the cheese body remains acid, hard and crumbly. A study of the causes of this phenomena is reported in the present work. Cheesemaking was performed using either a direct starter of Streptococcus salivarius ssp. thermophilus strains (control) or a natural milk culture (experimental). The curd was allowed to reach pH 5.2 for control cheeses and 4.7 for experimental ones before salting. Proteolysis characterisation was performed by nitrogen fraction analysis, Urea-PAGE, RP-HPLC and free amino acid analysis. Texture and appearance were very different. Control cheeses were soft and creamy, while experimental cheeses exhibited defective texture. Proteolysis in both of them was nevertheless similar. It is concluded that texture defect can be related, in this case, to the large influence of pH of the curd before brining on casein micelles' network organisation and not to a minor degree of proteolysis.