Changes in the composition of juice expressed from Camembert cheese during ripening

Cheese can be considered as a paracasein network including fat and aqueous phases. Changes in the composition of the aqueous phase reflect the enzymatic and physico-chemical phenomena that occur in cheese during ripening. For the first time, juice was expressed by pressing from Camembert cheese ripened up to 16 d and analysed in addition to the cheese to evaluate the extent of proteolysis together with the solubilisation of minerals. The amount of expressable juice decreased sharply during ripening, i.e. from 67 to 19% of the total water content for cheeses ripened 0 and 16 d, respectively. In parallel, the levels of pH 4.6-soluble nitrogen and non-protein nitrogen increased in the whole Camembert cheese; the increase was higher in the juice. Simultaneously, the concentration of organic phosphate in the juice increased with concomitant decreases in the concentrations of calcium and inorganic phosphate. This last observation suggests that salt precipitates at the surface of the cheese. The expression and subsequent analysis of juice from Camembert cheeses is an appropriate method for following the sequential action of proteolytic enzymes and mineral transfer that occur during ripening. (C) Inra/Elsevier, Paris.