Just How Long Can Milk Sit Out Before Going Sour? Here’s The Magic Window

Don’t cry over spilled milk, said no mother ever. At least not if they were talking about actual milk. Why? Because babies and kids literally live off that sh*t! Spilled milk, spoiled milk… any loss of milk is a tragedy. Seriously, just ask a mom who has spent an hour pumping two ounces of breastmilk and then accidentally knocked it over with her boob. True story. Or that mom who ran a “quick” errand on the way home from the market on a stiflingly hot day, resulting in a brand new gallon of utterly useless, spoiled milk. Or was it? Exactly how long can milk sit out before going bad?

With the insane cost of groceries these days, you won’t want to throw out milk that could still be good, even after it’s sat out for a while. And if you’ve entered the tragic “danger zone,” you might just be able to use that spoiled milk in other ways, so it’s not a total loss. Here’s how to tell if that “white gold” is still good.

How can you tell if milk has gone bad?

The “danger zone” is a term coined by the U.S. Department of Agriculture to refer to foods that have been left out at room temperature for too long, developing the risk for sickness caused by dangerous levels of bacteria such as salmonella and E. coli. The USDA warns to “Never leave food out of refrigeration over 2 hours.” This includes pasteurized milk, which should be kept at or below 40 °F. If it’s a hot day, you can probably cut that time in half — or less.

You can also use common sense when determining if the milk has gone bad. Dump it if it has a strong, sour smell or chunky bits floating in it. If it’s only a little funky (smell-wise), go for it. And don’t forget that different milks are treated in different ways, giving unpasteurized milk and even breastmilk a little longer unrefrigerated shelf life — though still susceptible to causing illness if left out too long, especially in babies.

So what can you do with milk that’s still technically in the “safe zone?”

If the milk hasn’t been sitting out for more than two hours (and not at a high temperature), chances are that — while bacteria have surely begun to multiply — it’s still suitable for consumption. Maybe not in an “I could sure go for a cold, tall glass of milk” sort of way, but perhaps in these other applications.

1. Use “spoiled” milk for baking.

Remember those bacterias that form when dairy is left unrefrigerated? That’s pretty much the science behind buttermilk, or “fermented” milk, that has developed lactic acid-producing bacteria. The thick, tangy taste is great for baking and adding flavor and moisture while increasing leavening and breaking down gluten for a softer, more tender crumb.

2. Use “spoiled” milk to tenderize poultry and meat.

All that lactic acid is ideal for tenderizing poultry and meat by speeding up the breakdown of proteins and collagen that give poultry and meat its firm structure. Buttermilk fried chicken, anyone?

3. Use “spoiled” milk in your beauty routine.

Lactic acid has benefits beyond the kitchen. It’s also found in many beauty products labeled as AHA, or alpha hydroxy acid, and promotes cell turnover, leading to smoother skin. Add it to your bath or dilute it and use it as a facewash — rinsing thoroughly after!

4. Use “spoiled” milk in the garden.

The calcium, vitamin B, and proteins found in milk aren’t just good for the bones. Plants, particularly tomato plants, thrive when “watered” periodically with diluted milk, adding nutrients to the soil and even acting as a natural pesticide.

5. Use “spoiled” milk to make salad dressing.

In addition to using sour milk for baking or thickening soups and stews, you can put it to good use by whipping up some salad dressing. Tangy and creamy, salad dressings that utilize sour milk often involve only a handful of ingredients you probably already have, like egg, oil, vinegar, salt, and pepper.