Researchers at Cornell University have discovered that a microbacterium, a type of microbe that is resistant to pasteurization, can find its way into fluid milk during the filtration process. Microfiltration is a technique used to extend the shelf life of milk by using semipermeable membranes to filter out undesirable microbes. It is currently used in Europe and will soon be implemented in U.S. dairies. However, if the equipment used in the process is not properly cleaned, microbacterium can contaminate the milk.
The study, titled “Microbacterium Represents an Emerging Microorganism of Concern in Microfiltered Extended Shelf-Life Milk Products,” was published in the Journal of Dairy Science. The researchers emphasize the importance of thoroughly cleaning milk-processing equipment before the pasteurization process to avoid the presence of harmful microbes. While conventional fluid milk products typically have a refrigerated shelf life of 14 to 21 days, microfiltration can extend the shelf life to 60 days, reducing food waste.
High-temperature pasteurization, the current method used to extend the shelf life of milk, can result in undesirable flavors. Microfiltration offers a gentler alternative by using smaller membrane pores (0.8 to 1.2 microns) and maintaining the flavor of the milk. This technology also removes bacteria, allowing for the extended shelf life.
The researchers conducted their study on whole milk and skim milk processed using microfiltration. The milk samples were pasteurized and refrigerated at different temperatures for 63 days. They found significant differences in bacterial concentrations based on the temperature but no differences based on the fat content of the milk. Notably, they discovered that microbacterium was a significant contributor to the bacterial population in microfiltered milk and emphasized the need for addressing bacterial harborage sites before pasteurization.
As the dairy industry aims to distribute milk over longer distances, microfiltered extended shelf-life milk provides consumers with a high-quality product. However, there is a need to overcome barriers such as the presence of spoilage microbes. By addressing these challenges, the industry can ensure that consumers have a positive experience with extended shelf-life milk.
1. Microfiltration: A processing technology that uses semipermeable membranes to filter out undesirable microbes and extend the shelf life of milk.
– T.T. Lott et al, Microbacterium represents an emerging microorganism of concern in microfiltered extended shelf-life milk products, Journal of Dairy Science (2023). DOI: 10.3168/jds.2023-23734
– Cornell University