Have a tub of sour cream that's been sitting in the fridge for weeks, and wondering if it's still safe to eat? Here's how to tell.
The Shelf Life of Sour Cream
According to the USDA, sour cream (opened or unopened) is good for up to three weeks after the sell-by date, as long as it's been stored in the refrigerator. Inspect your sour cream to make sure it hasn't developed mold, an off-color or an off smell, and if nothing seems amiss, consider it safe to use.
This rule of thumb is backed up by the Food Marketing Institute in their "The Food Keeper" consumer guide to food quality and safe handling. They also give a seven to 21-day window for using sour cream, assuming it's been refrigerated at 40 F.
What Can Make Sour Cream Go Bad?
Sour cream is produced from milk that has been pasteurized to kill most harmful bacteria. It is then fermented by healthy bacteria that produce lactic acid, giving it the sour flavor. Commercially-produced sour cream must adhere to safety standards, while homemade sour cream may introduce a wild card of other bacteria types. Think of sour cream as a living product; it still contains live elements that were not killed by sterile canning processes.
Bacteria and Molds Enjoy Living in and on Your Sour Cream
The protein and sugars in the milk provide a happy culture medium for the friendly sour-producing bacteria, as well as a host of unfriendly bacteria and molds. These could include diarrhea-inducing bacteria. They may slowly multiply over weeks at refrigerated temperatures, or even faster if you leave your sour cream out at room temperature for any length of time.
And you may introduce additional bacteria and mold when go to use your sour cream, either from exposure to the air or by using a spoon that isn't clean.
Signs Your Sour Cream Has Gone Bad
Even if your sour cream isn't yet at the "best by" or "use by" date, don't eat it if you notice:
- An Off Smell: Take a whiff of your sour cream. If it smells moldy, rancid or stinky in any way beyond the usual sour smell, it probably has extra growth in it that will affect the flavor and safety.
- Mold: If you see mold growing on the surface, the whole container needs to go. Don't be tempted just to scoop the mold off the top and eat the rest. The mold may extend further than you're able to see with the naked eye.
- Yellow or Discolored Sour Cream: If the cream is no longer white, that's a strong sign that it has significant growth of bacteria and fungi.
The shelf life of foods can be significantly shortened if they aren't handled properly. Your sour cream may have been left out at room temperature at some point, whether by the manufacturer, vendor or someone who lives in your home. Or someone may have stuck a dirty finger or spoon into the container. Trust your eyes and your nose, when they tell you something isn't right.
One sign that isn't of concern is separation. It's normal for the liquid to separate from the solid cream. You can drain it off or mix it back in, as long as you use a clean spoon.