Have a tub of sour cream that's been sitting in the fridge for a while and wondering if it's still safe to eat? Here's how to tell.
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. This rule of thumb is backed up by the Food Marketing Institute in their consumer guide to food quality and safe handling, "The Food Keeper." They give a seven to 21-day window for using sour cream, assuming it's been refrigerated at 40 F.
Inspect your sour cream to make sure it hasn't developed mold, an off-color, or an off smell. If nothing seems amiss, consider it safe to use. One sign that isn't of concern is separation. While unsightly, it's actually 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.
What Causes Spoiling?
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, as it still contains live elements that were not killed by sterile canning processes.
Bacteria and Molds
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 that could cause illness. 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. You may also inadvertently 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 of Spoilage
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 utensil into the container. Trust your eyes and your nose when they tell you something isn't right.