Modelling of French Emmental cheese water activity during salting and ripening periods

Water sorption isotherms of French Emmental cheese have been determined at various temperatures (between 4 and 28 degreesC) for core or rind samples taken at various ripening stages during a standard 74 days ripening period. The differences observed between all the experimental isotherms are probably due to the evolution of product composition during the cheese ripening. Experimental data concerning the water activity profiles for industrially processed Emmental cheese have been collected after different brining experiments carried out at usual temperature conditions (4-18 degreesC) and all along the ripening cycle. The local water activity profiles during the Emmental brining and ripening periods are strongly dependent on the local NaCl concentration distribution. All these profiles vary in relation to the process step and of the process time. For the brining step, a precise correlation was proposed to express the influence of the water content and of the NaCl concentration. For the ripening period, a more general correlation expressing the water activity as a function of the water, NaCl and free NH2 group concentrations was fitted to our experimental data. This last correlation was able to interpret the activity profiles more precisely during an Emmental ripening cycle in industrial conditions than the physical models of sorption fitted to the water sorption curves. (C) 2003 Elsevier Ltd. All rights reserved.