How not to give your friends food poisoning: nine easy tips! Part 3: Well the sour cream is already sour, so…. The rules of dairy

We cleaned out the fridge this weekend at casa de Starter Kitchen, and WOW. Four twenty-somethings sharing a fridge means no one is responsible for that five-month-old package of cream cheese, or the yellow milk, or the mysterious cheese in a Tupperware container that may not have been blue cheese to begin with, but is now. Apparently, dairy products simply flock to our fridge when they reach retirement age, like our own little sour cream Florida.


My father always claimed that the sell-by-dates were just friendly suggestions – as long as they were purchased by that date, they were good for another month, or until his taste-test revealed that even he of the iron stomach and dead taste buds couldn’t stifle the reflex to spit out the offending food. So when does dairy food turn? How can you tell? And what the heck is that smell anyway?


Milk and cream: The time it takes for milk to spoil depends largely on its fat content. Skim milk is much higher in lactose, which turns to lactic acid as the product ages, and lactic acid promotes spoiling. The general rule for skim milk is no more than five days after the expiration date. It might still be safe to drink – but it might not. One percent milk buys you an extra day, 2% can stretch you to day seven, and whole milk and creams, if they have been kept in closed containers in the fridge, should be dumped after day eight.


The level of pasteurization will make a difference too. If you’re a raw milk enthusiast, you know you don’t have much more than five days from cow to your stomach unless you want to deal with an increasingly sour taste. The super ultra-pasteurized milk in your grocer’s fridge can last up to three times longer than regular milk – but only until it’s opened. Once the seal is broken, ultra-pasteurized milk spoils at the same rate as regular milk.


You can usually tell if milk has spoiled just by smelling it. But what causes milk to go bad, stink up your kitchen, and make you gag – and can it kill you?


The smell is caused by bacteria that thrive on the sugars and proteins found in milk. There are a variety of bacteria cultures that cause milk to spoil, and although most won’t kill you, they can make you very sick. So even if the milk tastes just a little off – dump it.


Other dairy: sour cream, cream cheese, cottage cheese, and soft cheeses are generally fine for 5-10 days after the sell-by date if properly stored. If there is ANY sign of mold or discoloration, throw it out.


BONUS FACT: When unpasteurized milk was common in the US, many recipes called for sour milk. Sour milk is NOT the same as spoiled milk. Sour milk is made when natural bacteria found in unpasteurized milk are allowed to grow – those bacteria are killed off in the pasteurization process – so the milk you get from the grocery store isn’t souring – it’s rotting. If you need sour milk for a recipe, add 1 tablespoon of lemon juice per cup of pasteurized milk and let it stand for five minutes.






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