Scientists at Purdue University and the University of Tennessee have come up with a new look at an old product. Working together, they have created a pasteurization method that significantly extends the shelf life of milk.
A staple at every kid’s breakfast and a prime source of protein, vitamins and minerals for all ages, milk and the process of bringing milk to tables around the country has been relativelyunchanged for generations. Pasteurization involves heating the milk to temperatures (70 degrees Celsius is the key marker) that kill harmful bacteria and reduce the risks of food-borne pathogens. But current pasteurization methods don’t get rid of all bacteria, with the result being that unopened milk tends to last for only one to two weeks. Enough time to get it to the store and into people’s refrigerators, of course, but not good enough to prevent waste or to allow transportation to distant locales, say the authors of the new study.
“Unfortunately, many characteristics of the pasteurization process are neither effectively robust nor cost effective,” say the authors who also taking aim at how current methods not only cause damage to proteins within the milk but change the taste. “A viable process would reduce costs and energy input, improve the quality of the product, and maintain or improve microorganism reduction potential.”
Their new method, say the researchers, does just that. The process works by delivering milk in tiny droplets through a pressurized chamber that quickly heats the milk for 0.02 seconds to temperatures below those of traditional pasteurization. What results is a product virtually free of all bacteria and therefore able to maintain its quality for much longer periods of time, up to 63 days.
“With the treatment, you’re taking out almost everything,” says study author Bruce Applegate, associate professor in Purdue’s Department of Food Science. “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.”
What’s more, the new process is a very energy efficient way of pasteurizing milk, and people seem to like the taste – panelists who examined the colour, aroma, taste and aftertaste of the milk were either unable to distinguish it from the regularly pasteurized milk or actually favoured it over the standard product.
The work is all part of a need in the dairy industry to modernize and become more sustainable, say the study’s authors. “The manufacturing and distribution dynamics of the fluid milk industry are constantly impacted by the primary concern of prolonging shelf-life and improving safety,” they write. “Together with rising fuel costs, the industrial sector must find solutions to minimize energy and fuel consumption in order to cut expenditures and reduce their carbon footprint.”
The innovation comes in the midst of a decades-long decline in milk sales, as consumers turn in greater numbers to dairy-free beverages and other sources of protein. Per-capita milk consumption in Canada dropped by 18 per cent between 1995 and 2014. Canada’s food guide recommends that adults drink two cups of milk a day to obtain sufficient vitamin D but adds that fortified beverages such as soy milk can work as a substitute.