EQUILIBRIUM BETWEEN THE PROTEIN MATRIX AND THE SERUM PHASE OF PRATO CHEESE

Prato is a Brazilian cheese produced from a washed, semicooked curd obtained by enzyme coagulation, which is brine-salted and ripened for at least 25 days. This study evaluated Prato cheese and its expressible serum during the initial stages of ripening. The experiment was done in triplicate and the results were analyzed by analysis of variance and linear regression. There were an increase of water-holding capacity and a decrease of expressible serum, tending to zero during the five first ripening days. The total protein increased twice as fast as the pH 4.6-soluble protein in the expressible serum. The electrophoresis showed progressive migration of β-CN, αs1-CN, αs1-I-CN and γ-CN from the cheese matrix to the serum phase, and αs1-CN hydrolysis in cheese matrix. The observed changes suggest that besides proteolysis, the increase of the water-binding capacity of protein matrix should improve the sliceability and meltability of Prato cheese at the initial stages of ripening. PRACTICAL APPLICATIONS The Brazilian legislation requires at least 25 days for the Prato cheese developing its functional properties. However, the major changes in the cheese water-holding capacity profile seem to occur during the five first days of ripening, showing that this period may be the main one improving the cheese functionality as a result of the protein matrix hydration. Thus, the ripening required by law could be shortened, reducing the total cost of the Prato cheese manufacture.