ON UPSCALING A CURD PARTICLE MODEL TO BATCH PROCESSING SCALE

Drainage of curd is the separation of solid curd grains and whey, an e ssential process step in making cheese. It is difficult to model this process by use of current consolidation theories, mainly because of th e considerable loss of whey by the curd grains themselves during the e xpulsion of whey from pores between the curd grains. As an alternative we have studied a model that takes the expression of a single curd gr ain as a starting point. By analyzing experimental results of a column filled with uniform curd grains drained in radial direction while bei ng under axial external pressure, we study the question to which exten t 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 inadequat e. In the intermediate pressure range the model predicts too fast an e xpression of the curd grains, although a liquid pressure gradient betw een the center and the outside of the curd column could not be detecte d. This suggests the existence of isolated pores, or a geometric limit ation of the deformation of curd grains in a curd bed.