A new study conducted by Cornell food scientists has revealed that if equipment is not properly cleaned during the milk filtration process, it can result in a pasteurization-resistant microbacterium passing into fluid milk. Microfiltration is a processing technology that uses semipermeable membranes to extend the shelf life of milk by keeping out undesirable microbes. This technology is currently being used in Europe and will soon be introduced to dairies in the United States.
The study found that without proper cleaning of the equipment early in the process, a microbe called microbacterium can end up in the milk. The researchers emphasized the importance of cleaning milk-processing equipment before pasteurization. They recommend thorough cleaning of the intake equipment for raw milk prior to processing to remove these microbes.
Currently, conventional fluid milk products have a refrigerated shelf life of 14 to 21 days. However, with the addition of microfiltration, the shelf life can be extended to 60 days, reducing food waste. Microfiltration, with its gentler alternative to high heat treatment, not only maintains the milk flavor but also removes bacteria through the filtration process.
In their research, the scientists examined whole milk and skim milk processed using microfiltration, pasteurized, and refrigerated at different temperatures for 63 days. The analysis revealed significant differences in bacterial concentrations for the microfiltered milk held at different temperatures but no difference based on fat levels.
An unexpected finding was the identification of microbacterium as a major contributor to the bacterial population in microfiltered, extended shelf-life milk. The researchers suggest that on-farm and pre-pasteurization bacterial harborage sites need to be considered in order to address this issue.
As the dairy industry aims to provide consumers with a high-quality product and longer distribution, extended shelf-life milk offers a quality product but requires careful attention to potential barriers. By implementing proper cleaning practices and addressing microbial concerns, the dairy industry can ensure that consumers have a great experience with extended shelf-life milk.
Sources:
T.T. Lott et al, Microbacterium represents an emerging microorganism of concern in microfiltered extended shelf-life milk products, Journal of Dairy Science (2023).
Cornell University
