Methods of Manufacture of Paneer and Chhana

Paneer, the indigenous variety of soft cooking type cheese, is obtained by the heat and acid coagulation of milk at relatively higher temperature. The chemical and physical changes in casein and whey proteins brought about by the combined action of heat and acid treatments, form the basis of paneer making. When milk is acidified, the colloidal calcium phosphate in the casein micelles progressively solubilises and aggregation of the casein occurs as the isoelectric point is approached. In milk of normal pH, the casein micelles are stabilized by hydration and steric repulsion due to their negative charge. On acidification the micelles become unstable and aggregate as a result of charge neutralization, leading to the formation of chains and clusters that are linked together to give a three-dimensional network. In milks preheated at high temperatures (90oC), gelation occurs more rapidly at a higher pH than in unheated milk. Interaction of whey proteins with casein micelles on heating milk at its natural pH may increase the hydrophobicity of the micellar surface and reduce the hydration barrier against aggregation, thus allowing aggregation and gelation to occur at a higher pH than in unheated milk. Heating milk also results in dissociation of k-casein from micelles, and this could further sensitize the α-s-casein framework to calcium-induced aggregation. The development of typical rheological characteristics of paneer could be due to the intensive heat induced protein-protein interactions. Paneer manufacture essentially involves the formation co-precipitates due to complexing of whey proteins denatured by the heat and the casein. Serum proteins,particularly β-Lactoglobulin, are bonded to κ-casein via disulphide bridges and calcium linkages. The higher the degree of co-precipitation, the greater will be the total solids recovery and yield of paneer.