Reducing salt level in food: Part 2. Modelling salt diffusion in model cheese systems with regards to their composition

In the first part of the paper (Floury, J., Camier, B. Rousseau, F., Lopez, C., Tissier, J. P., & Famelart, M. H. (2009) Reducing salt level in food: Part 1. controlled manufacture of model cheese systems and their structure-texture relationships. LWT – Food Science and Technology 49(10), 1611–1620), a model cheese matrix presenting different textural properties was developed in order to further study the factors implied in the salt release in mouth during food chewing. The present work consists in physical and modelling approaches to better understand the mass transfer phenomena occurring in the product during its consumption in the mouth. Concentration profiles of several ionic species were measured during the release of salt from the different model matrices into artificial saliva. Apparent diffusion coefficients of the sodium chloride were determined by fitting the experimental data to the second Fick's law. Apparent diffusion coefficients were included between 2.81 and 3.43 × 10−10 m2 s−1 at 15 °C and 75% HR. D-value decreased strongly when the dry matter content decreased. Microstructure of the matrices with the lower protein concentration was coarser and fluffier, facilitating the diffusion of the solutes. The D-value increased with the pH at renneting, probably because of the chemical changes of the structure of the casein micelles and significant differences in textural characteristics of cheeses. The diffusion coefficient also significantly decreased with the initial salt concentration, due to the tightening of the matrix microstructure.