A rapid heating and cooling of milk significantly reduces the amount of harmful bacteria present, extending the shelf life by several weeks, according to a Purdue University study.
The findings from the university based in the US, show that increasing the temperature of milk by 10 degrees for less than a second eliminates more than 99% of the bacteria left behind after pasteurisation.
Bruce Applegate, Purdue associate professor said: “It’s an add on to pasteurisation, but it can add shelf life of up to five, six or seven weeks to cold milk.
“With the treatment, you’re taking out almost everything. Whatever does survive is at such a low level that it takes much longer for it to multiply to a point at which it damages the quality of the milk.”
The low-temperature, short-time (LTST) method in the Purdue study sprayed tiny droplets of pasteurised milk, which was inoculated with lactobacillus and pseudomonas bacteria, through a heated, pressurised chamber, rapidly raising and lowering their temperatures about 10 degrees Celsius but still below the 70-degree Celsius threshold needed for pasteurisation.
The treatment lowered bacterial levels below detection limits, and extended shelf life to up to 63 days.
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