Researchers at Purdue University say a new process could extend milk’s shelf life to as long as nine weeks.
Bruce Applegate, an associate professor of food science, says he and other researchers rapidly heated and cooled milk, which significantly reduced the number of harmful bacteria.
Applegate and collaborators from Purdue and the University of Tennessee published their findings in the journal SpringerPlus.
They used milk inoculated with bacteria and quickly raised the milk’s temperature by 10 C, then just as quickly lowered it, without reaching the 70 C threshold that’s considered pasteurization. They found increasing the temperature of milk by 10 C for less than a second eliminates more than 99 per cent of the bacteria left behind after pasteurization.
“It’s an add-on to pasteurization, but it can add shelf life of up to five, six or seven weeks to cold milk,” Applegate said.
The treatment lowered bacterial levels below detection limits, and extended shelf life to up to 63 days.
“With the treatment, you’re taking out almost everything,” Applegate said. “Whatever does survive is at such a low level that it takes much longer for it to multiply.”
Phillip Myer, an assistant professor of animal science at the University of Tennessee and a co-author of the paper, said the process uses the heat already necessary for pasteurization.
“The process significantly reduces the amount of bacteria present, and it doesn’t add any extra energy to the system,” Myer said.
Myer said the promise of the technology is that it could reduce waste and allow milk to reach distant locations.