Influence of low calcium and low pH on melting characteristics of model Raclette cheese

Abstract

The aim of this study was to demonstrate the influence of calcium (Ca) reduction on model Raclette cheese meltability using different technological and chemical methods. Analysis was carried out on the detailed chemical, textural and rheological properties of six different model Raclette cheeses: control Raclette cheese manufacture (CON); pre-ripening (PRE) of the cheese milk; and addition of either 50 or 25 g of citric acid to the wash water (CA50 and CA25) and addition of either 70 or 35 g of lactic acid to the wash water (LA70 and LA35). The compositional analysis of the samples was carried out within the first 24 h of manufacture and after 14 weeks of ripening. In particular, total calcium, insoluble calcium (Insol Ca), nitrogen fractions and pH were examined as they were considered important parameters for meltability. Total Ca and Insol Ca were both remarkably reduced in CA50 and CA25, and were increased in PRE, LA70 and LA35 compared to the CON. The results of this study suggest that citric acid in the wash water lowered the pH value of the Raclette cheese and chelated Ca from the colloidal calcium phosphate, but also changed the rheologically determined melting properties. Various parameters of the small amplitude oscillatory shear test as well as the increase in the force in the compression test and the elevated softening and dropping points all indicated a firmer texture of the CA50 and CA25 cheeses. However, the sensory data for CA50 revealed good “viscous”, “ropy” and “gummy” properties of the melted cheese. The apparent discrepancy between the sensory sensation and the rheological data seems to be related to changes in the water-binding capacity of the protein matrix.