Abstract:Room temperature processed cheese products, referring to the sterilized cheese, can be stored at room temperature after being treated by ultra-high temperature treated (UHT). It is a hot spot in China’s dairy industry. However, processed cheese is prone to instability after UHT treatment, resulting in gel structure reconstruction, water precipitation and other texture problems during storage, which affect the product quality. It was intended to clarify the effect of protein raw materials on the water precipitation of room temperature processed cheese products and its mechanism. Three different protein raw materials: membrane filtration casein micelle, concentrated milk protein and rennet casein were screened, and their protein content and composition as well as their physical and chemical properties such as particle size, potential, hydration and calcium ion distribution were analyzed. Secondly, the effects of protein raw materials on the water precipitation and texture properties of room temperature processed cheese products were analyzed. The mechanism of the effect of protein raw materials on the water precipitation of room temperature processed cheese products was analyzed from the aspects of water distribution and microstructure. The results showed that there were significant differences in protein composition among the three protein materials. The whey protein content of concentrated milk protein was 7.81 percentage points higher than that of membrane filtration casein micelles, while rennet casein did not contain whey protein. In terms of hydration, concentrated milk protein and membrane filtered casein micelles were similar and significantly higher than rennet casein. Protein raw materials significantly affected the water precipitation of room temperature processed cheese products. When stored for 90d, the water precipitation rate of room temperature processed cheese products prepared from rennet casein was the highest, while that of room temperature processed cheese products prepared from concentrated milk protein was the lowest, and its surface water precipitation rate and centrifugal water precipitation rate were 0.42% and 1.10%, respectively. The results of water distribution and microstructure showed that the protein raw material affected the water precipitation of room temperature processed cheese products by affecting the existing state and three-dimensional network spatial structure of water in processed cheese. The effect and mechanism of different protein raw materials on the water precipitation of room temperature processed cheese products was analyzed, which provided a theoretical basis for improving the water precipitation of room temperature processed cheese products.
