Caustic curdlersBy Kim Smith • Published: October 8th, 2012
Category: Health in a Heartbeat
Pasteurization controls the bacteria in dairy products through a process of heating and cooling. But certain milk-fouling microbes may thrive on extreme climate change.
Scientists at Cornell University say they have identified predominant strains of bacteria that spoil milk and take the delight out of dairy. But turning the heat too high on these caustic curdlers … a time-honored way to kill germs … apparently reduces the effectiveness of pasteurization.
The resistant strains survive the initial heat blast by morphing into spores, which enables them to wait out thermal adversity and reproduce later in the chilly confines of a carton.
According to the National Dairy Council, pasteurization is essential to ensure that milk and dairy products are safe, tasty and nutritious.
Under U.S. guidelines, raw milk must be heated to a minimum of 145 degrees for 30 minutes, or to 161 degrees or higher for 15 seconds.
Researchers in the Milk Quality Improvement Program at Cornell’s College of Agriculture and Life Sciences counted bacteria in milk that had been pasteurized at two very high temperatures … 169 degrees and 175 degrees.
In an apparent case of “less is more,” the food scientists discovered that the growth of undesirable bacteria was reduced in milk pasteurized at the lower temperature.
Higher temperatures may have actually primed the spores to revive in cooler temperatures, allowing them to prey on milk freshness, especially after 21 days.
Food scientists say it is important to learn more about spore-forming bacteria and how to extend the shelf life of dairy products such as milk and cheese.
In a nation with millions of mouths to feed, spoiled milk is certainly something to cry about.