Abstract: Milk is an excellent medium for the growth of microorganisms, which is easily contaminated by microorganisms from the environment. Psychrophilic bacteria are the most common microorganisms in cold-stored raw milk. Moreover, psychrophilic bacteria produce heat-resistant proteases and lipases in low-temperature environments, which remain active even after heat treatment, and decompose proteins and fats in liquid milk during storage, thereby affecting the quality of milk. The counting method for psychrophilic bacteria in milk specified by the agricultural industry standard of China takes 10 days to culture samples at 6.5 ℃ for 10 days, which is time-consuming and has low application value in actual production. Therefore, the development of detection technologies for psychrophilic bacteria and their heat-resistant enzymes is very important for ensuring the quality of milk and dairy products. This article reviews a variety of methods for the identification and analysis of psychrophilic bacteria in milk, including polymerase chain reaction (PCR), sequencing, fluorescence in situ hybridization, and loop-mediated isothermal amplification. It provides a reference for the development of new detection technologies for psychrophilic bacteria in milk.

Key words: raw milk; psychrophilic bacteria; heat-resistant enzyme; detection method