This paper sets out a method to extract Maxwell model parameters from experimental compression-relaxation tests and investigates common experimental sources of bias when dealing with viscoelastic materials. Particular attention was given to viscoelastic materials that relax stress quickly. The proposed method differs from the methods usually used in that it takes into account the stress that can relax when a material is submitted to compression before proper relaxation. Among the experimental biases that can affect the tests, this study investigated the impact of the geometry defects of the samples, of the sensitivity of the rheometer used and of the compression speed on the characterization of the material. The uncertainties caused by these biases were then propagated in the proposed method. The proposed method was used to study the evolution of the viscoelastic properties of semihard cheese during ripening. Variability between cheeses proved to be greater than the uncertainty of the proposed method, and no tendency could be established, meaning that the viscoelastic parameters were considered constant during ripening

This paper proposes a model for bubble growth in semi-hard cheese coupling mechanical behaviour and mass transport. The modelling follows previous work centred on the mechanical aspects, and focuses in this paper on the mass transport phenomena. Data are compared to experimental results obtained on industrial-size cheeses, both under the rind and at core, and a sensitivity study is conducted to discuss the results. The model is in agreement with experiment at core, and underlines the great influence of the carbon dioxide production rate and the amount of cheese material surrounding the bubble on bubble growth. Under the rind, the model yielded poorer agreement, due to the fact that this region in the cheese is less homogeneous, and therefore with more intra- and inter-batch variation on the parameters that were characterized.

Although PE-based nanocomposites are gaining interest within the food packaging industry for their outstanding functional properties, their end-of-life has been poorly studied. The lack of identification of such materials suggests that they could end-up in the recycling pathway optimized for the decontamination of un-filled PE. The objective of the present work is to understand and quantify the mechanisms involved in the high temperature desorption of surrogates for PE nanocomposites filled with organo-modified montmorillonite (PNC), compared to conventional PE. An original experimental setup was coupled with a modelling approach to identify the two phenomena involved in the decontamination process: diffusion of the surrogate into the bulk and its evaporation at the surface. A sweep of experimental temperatures enabled the determination of diffusion and evaporation parameters for PE and PNC and the activation energies related to the diffusivity among those two materials. The effects of the introduction of clay nanofillers onto the decontamination process have been explained and recommendations for the recycling pathway have been put forward.