How Long Is Opened Kefir Good For?

Kefir might seem kind of intimidating. After all, it's over 4,000 years old and hails from the Caucasus Mountain region which includes parts of Armenia, Azerbaijan, Georgia, and Russia. But it's actually a super approachable yogurt-like beverage with many health benefits. Because it's a fermented drink (with a characteristic tang), it contains a plethora of probiotic bacteria, which are good for the gut. In the 21st century, companies have hopped on the kefir train, selling bottled versions in supermarkets in the dairy coolers. Once you bring it home and open it, though, how long do you have to drink it before it can start to go bad?

Opened kefir must be kept refrigerated, and will keep up to two weeks if stored properly. (One popular brand of kefir, Lifeway, states that the drink is good until the sell-by date on the bottle. So, whether that comes sooner or later than within two weeks of opening it, you should be fine to trust the guidelines for that specific brand.) Kefir should not be allowed to sit at room temperature for longer than two hours, though. It's always best to put it back in the fridge after you're done using it.

It's also important to mind any potential instances where you could be introducing new, bad bacteria to your kefir container. This could include putting a dirty spoon to the mouth of the bottle when cooking or baking with it, or drinking straight from the bottle. For the latter, while you might reason that you're the only one in your household drinking it, you are nonetheless contaminating what's left in the bottle; which could accelerate spoilage.

Tempting though it is to keep kefir in the door of your refrigerator for easy, convenient access, the temperature fluctuations every time you open it can also make it go bad more quickly. Instead, much like milk, you should store it on the lowest shelf possible, near the back, where the air is coolest and the kefir is less likely to be affected by the rush of warm air every time you open the fridge door. It's even better if you can avoid one of the biggest food storage mistakes by writing the date you opened it on the bottle in marker.

Finally, you can freeze kefir and it will still keep most of its nutritional value, but it might change the texture when it thaws; causing some separation. To freeze, transfer the kefir from its bottle into an airtight container or freezer bag and for the best quality, keep frozen for only up to three months.

Unfortunately, despite its relatively long refrigerator life, all good kefir must come to an end. Here are some of the signs that it has spoiled: First, you might notice your white kefir is starting to yellow (if you have a flavored kefir that is pink or blue, any changes from that original color is what you'll be looking out for). When you pour it out, if the curds are curdling and clumping quite a bit, that's also an indicator that you should toss it.

There is also the smell to consider. Kefir does already have a distinctive tangy scent to it, but if you open it and find it veering toward truly sour (or worse, rancid and rotten), you've got some bad kefir on your hands. Finally, the appearance of mold, either on the surface of your kefir or clinging to the interior of the bottle, is a sign you need to get rid of it, posthaste.