ON UPSCALING A CURD PARTICLE MODEL to BATCH PROCESSING SCALE

Abstract

Drainage of curd is the separation of solid curd grains and whey, an essential process step in making cheese. It is difficult to model this process by use of current consolidation theories, mainly because of the considerable loss of whey by the curd grains themselves during the expulsion of whey from pores between the curd grains. As an alternative we have studied a model that takes the expression of a single curd grain as a starting point. By analyzing experimental results of a column filled with uniform curd grains drained in radial direction while being under axial external pressure, we study the question to which extent this model might be used to predict the change of porosity with time. It appeared that the model gives reasonable results at low external pressures. At high external pressures the model proves to be inadequate. In the intermediate pressure range the model predicts too fast an expression of the curd grains, although a liquid pressure gradient between the center and the outside of the curd column could not be detected. This suggests the existence of isolated pores, or a geometric limitation of the deformation of curd grains in a curd bed.