Cool-temperature process extends milk shelf life

Rapid heating and cooling by 10 C

Purdue University researcher Bruce Applegate says the system could be tested to see if it works without pasteurization.  (Purdue Agriculture Communication photo/Tom Campbell)

Purdue University researchers say they have developed a milk preservation system using a lower temperature than pasteurization, but providing a longer shelf life.

The researchers found that increasing the temperature of milk by 10 C for less than a second and then cooling it rapidly 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,” associate professor Bruce Applegate said in a Purdue release.

The release saud the low-temperature, short-time (LTST) method sprayed tiny droplets of pasteurized milk inoculated with Lactobacillus and Pseudomonas bacteria through a heated, pressurized chamber, rapidly raising and lowering their temperatures about 10 C but still below the 70 C threshold needed for pasteurization. The treatment lowered bacterial levels below detection limits, and extended shelf life to up to 63 days.

Applegate said the process could be tested without pasteurization to determine if it could stand alone as a treatment for eliminating harmful bacteria from milk.

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