Abstract: The total number of bacterial colonies in milk is one of the important indexes to measure the quality of milk. In order to ensure the quality of milk, the total number of bacterial colonies in milk must be controlled. The larger the number of colonies in milk, the more unstable the quality of milk. However, because of the origin of milk and other reasons, milk must be transported for a period of time before it can reach the factory for production, which may lead to the decline of milk quality in the process of transportation. In this experiment, the raw milk of two dairy households with different base number of colonies was selected for the test. The simulated raw milk was stored at 2 to 6 ℃ and 10 to 15 ℃ for cold storage, transportation and decooling, and the total number of colonies, acidity, alcohol and lipase activity were tested after 24 h , 48 h , 72 h and 96 h storage respectively. By comparing and finding some trends, optimal storage temperature and transportation time of raw milk can be found, and some suggestions for dairy processing enterprises and cold chain transportation can be provided.

Key words: cow raw milk detection, total number of colonies, alcohol test, storage temperature, transportation time