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Spoiled Milk

May 16, 2012

A listener asks why milk goes bad more quickly than other beverages.



Microbes in milk…I’m Bob Hirshon and this is Science Update.

Science Update listener Sam from Los Angeles called us with this question:


“Why does milk spoil so much faster than other beverages?”


For the answer, we consulted Cornell University microbiologist Kathryn Boor. She says because milk promotes the rapid growth of young mammals, it’s full of nutrients.

KATHRYN BOOR (Cornell University):

And as a consequence of its dense nutrient qualities, it also supports rapid growth of microbes.


She says this is compounded by the fact that barns are the perfect environment for microbes to enter into the milk supply. Pasteurization, or heating the milk to 161 degrees Fahrenheit for 15 seconds, destroys most bacteria, including those that could potentially harm us, but also those which make milk go sour. And if you have a science question, give us a call at 1-800-why-isit. If we answer your question, you’ll win a Science Update mug! I’m Bob Hirshon, for AAAS, the science society.

Milk is full of nutrients - which support the growth of pathogens - as well as baby mammals. (Keith Weller/USDA)