The purpose of this project is to observe any correlation between the structural changes of cheese proteins ((1-casein, (-casein, (-casein) and rheological behavior during to the heat and cold treatment. The temperature dependencies of the NMR spectra will be measured in the temperature range between -20 xC to 70 xC, with about 4 xC steps, and in the acidic pH range. The three spectra corresponding to structures in the cold-denatured, native and heat-denatured states will be detected. It is expected that the tertiary structures are different in the three states. Unlike many typical globular proteins, such as the whey proteins, caseins are not present in milk as individual molecular structures but, rather, as large protein complexes (casein micelles) which incorporate milk salts, particularly those of calcium. Thus, the native structure is actually a protein complex resulting from interaction of all the individual casein molecules. Nevertheless, an understanding of the individual structure of the casein molecule may lead to an insight into how these molecules may interact to form the large casein micelle complex.