Some spore-forming bacteria survive the pasteurization process so when milk processors label milk with sell-by and use-by dates, they are using experiential data to predict how soon these bacteria might cause off flavors or curdling.
“This is a considerable problem. If we can reduce the spoilage from spore-forming bacteria — by reducing their presence and by controlling their outgrowth — we can see shelf life for milk improve from two weeks to perhaps a month,” said Nicole Martin, a research support specialist at Cornell’s New York State Milk Quality Improvement Program laboratory.
A team of Cornell University food scientists created a new predictive model to examine how spore-forming bacillus emerge and affect pasteurized milk stored at different temperatures.
Colder is better
According to the study, refrigerated milk stored at 39.2°F had much lower concentrations of these spore-forming bacteria compared to the same milk stored at 42.8°F. After 21 days, only 9 percent of the half gallons stored at the lower temperature were spoiled while 66 percent of the half gallons stored at the higher temperature were.
They shared that their model could be foundational in developing technologies that will move away from dates on cartons and toward indicators that predict shelf life in the consumer’s refrigerator.
Why does this matter?
According to Agricultural Research Service data, from 2007 to 2014, U.S. consumers discarded 150,000 tons of food daily. Following fruits and vegetables (39 percent of waste), dairy foods made up the greatest portion of that waste at 17 percent.
This considerable waste tells a story of more opportunities to identify and improve our food preservation story. Perhaps that begins by storing milk at a lower temperature and further identifying the spore-forming bacteria that contribute to these off flavors.