Influence de l'affinage sur les propriétés rhéologiques du camembert et du saint-paulin

Abstract

Summary - Effect of cheese ripening on rheological properties of camembert and saint-paulin cheeses. The influence of ripening on the rheological properties of cheese has been evaluated by using 2 mechanical tests : the uniaxial compression and the stress relaxation. The calculated rheological parameters from an uniaxial compression test were the force of yield point, the relative deformation at yield point and the deformability modulus. From relaxation curves, 2 parameters were calculated : the half-relaxation time and the residual force/initial force ratio. Beside the latter parameters, an exploitation of the relaxation curves, according to the Maxwell generalized model, allowed to show that the 2 test cheese types exhibit a viscoelastic behaviour. It has been shown that these rheological properties change during ripening. Such evolutions are not always similar for the 2 investigated cheese types (camembert and saint-paulin). For example, from the beginning to the end of ripening, Ose varies from 70 to 40% for camembert, and trom 62 to 70% for saint-paulin. This can be explained by the more heterogeneous character of camembert paste. Conversely, the evolutions of the R1/2 are reverse for the 2 cheese types. An explanation can be given if we state that the stress relaxation (10 min) is probably incomplete for camembert cheese. The adjustment of the relaxation experimental curves to the generalized Maxwell model requires the use of 2 elements in the saint-paulin case, while 3 elements are required in the camembert case. From the multiple linear regression analysis, it could be demonstrated that many parameters are correlated with the ripening degree or the water content. Moreover, some important differences