Changes in properties and casein structure in stored processed cheese

In a stored processed cheese, some properties, such as firmness, heat stability and potency as a reworked cheese, gradually change. The tendency of these changes seems to be similar to the changes caused by creaming of processed cheese. The previous study has revealed that the changes caused by creaming are due to structural changes in casein; that is, the soluble casein submicelles dispersed by the action of the emulsifying salt are reconstructed during creaming to make an insoluble casein network, which plays a key role in the altered properties of the processed cheese. In this study, size-exclusion chromatography of the soluble protein in processed cheese showed that the same changes observed during the creaming process occur little by little during storage of a processed cheese. Formation of an insoluble casein network also played a key role in the changes in the processed cheese during storage, and formation of this network required 60 days or more of storage at 5 degrees C. The velocity of the changes that occurred during storage depended on temperature in the same way as general chemical reactions.