Having just returned from a few days at the Wisconsin State Fair, all things dairy are on my mind. My fellow fair lovers will know that the Wisconsin State Fair routinely ranks in the top 10 best fairs in the United States, often vying for the top spot. While every excellent fair has unique attributes that earn it acclaim, one of Wisconsin’s claims to fame is its attention to the state’s reputation as “America’s Dairyland.”
The cream puff — a delicious, hand-made concoction — gets the most attention during the fair, and more than 315,000 cream puffs were sold during the 2016 event. Yet, it is far from the only dairyland delight. During the 11-day affair, attendees gobbled up ice cream cups, cones and sundaes, grilled cheese sandwiches, fresh cheese curds and all manner of deep-fried cheese, and savored sips from the ever-popular milk cups — of which, more than 160,000 typically are sold during the fair.
While the milk sold at the just-finished fair disappeared at such a rate that shelf life was of little concern, extending milk’s shelf life is a regular research subject. First developed by Louis Pasteur in 1864, pasteurization is a tried-and-true preservation method effectively used for dairy products, beer and juices. Though other methods exist, most milk producers use the high-temperature, short-time pasteurization method. During pasteurization, the milk is heated to 161°F (72°C) for 15 seconds, and this heat treatment provides milk with a two-to-three-week shelf life.
Researchers at Purdue University, West Lafayette, Ind., have identified a supplemental process that shows promise for increasing milk’s shelf life from weeks to months. Dubbed the low-temperature, short-time (LTST) method, the post-pasteurization technique involves spraying tiny droplets of pasteurized milk through a heated, pressurized chamber. While keeping the milk’s temperature below the 161°F level used during pasteurization, the milk is rapidly heated by approximately 18°F (10°C) for less than a second, then cooled.
During their testing, the researchers inoculated pasteurized milk with Lactobacillus and Pseudomonas bacteria prior to the heat treatment to evaluate the veracity of the LTST method. The treatment lowered bacterial levels below detection limits and extended shelf life to up to 63 days. The LTST chamber technology was developed by New York-based Millisecond Technologies. The process uses the heat already produced to pasteurize the product to complete the post-pasteurization LTST step, which means the additional step does not “add any extra energy to the system,” says Phillip Myer, an assistant professor of animal science at the University of Tennessee and a co-author of the paper, in a release.
According to the findings published in SpringerPlus (http://bit.ly/LTSTmethod), the LTST method eliminates more than 99 percent of the bacteria left behind after pasteurization. Future research by the team will examine how well LTST fares against more thermally robust microorganisms.