safety of expired milk

Mark RepliesCategory: General questionsafety of expired milk
April Haines asked 1 year ago

How long can someone in their 60s use expired milk for? ie, if it expired 1 day ago, I would think it is still safe for 3 days

1 Answers
Mark Staff answered 1 year ago

Hi April
The expiry date on milk is not related to safety but instead to quality.
When milk is pasteurized, pathogens are killed but some spoilage organisms, especially those bacteria that exist as heat-resistant spores, may survive heat-treatment during pasteurization. And so, if pasteurized refrigerated milk is kept longer than the stated expiry date, then the spoilage bacteria can grow to levels that make the milk taste and/or look bad. Again, these are not pathogens but spoilage organisms that normally do not cause human infections and illness.
If you never opened the milk container and just left it in the refrigerator past the expiry date, the spoilage bacteria would still grow. However, with milk that is ultra-pasteurized, which is the type milk that you can find on non-refrigerated shelves in a food store, the heat-treatment is much longer and kills many more spoilage bacteria. As a result, this type of milk takes a much longer time to spoil.
All that I have said above assumes that a person has not accidentally contaminated the milk with pathogens after they opened the container, such as with contaminated hands or utensils. If this happens, you should always throw it out.
If you have any further questions, please let me know.
Mark

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