You’re all set to dig into your favorite yogurt. But when you peel back the lid, you notice the lush creaminess is marred by a watery pool of liquid sitting right on top. So what is that liquid—and more importantly, is it telling you that your snack has gone bad?
While the watery stuff might not look the most appealing, it’s perfectly safe to eat and isn’t hinting at any kind of spoilage, nutrition expert Amanda Sauceda, RDN, tells SELF. In fact, the liquid on top of your yogurt is a simple byproduct of the yogurt-making process.
Turns out, that yellowish water is actually whey, the watery, protein-rich component of milk. “When milk is coagulated to make cheese or yogurt, you get the curds—which is the actual cheese or yogurt part—and the whey, which is the liquid part,” homemade yogurt maker Janet Fletcher, author of Yogurt and the Planet Cheese newsletter, tells SELF.
Much of the whey is pressed out of cheeses, especially firmer ones like cheddar or Swiss, which is why you don’t see liquid seeping out of them. But keeping most of the whey is what gives yogurt its softer, thinner consistency, Sauceda points out.
When yogurt sits for a while undisturbed, that whey starts to separate. “If the yogurt was sitting over a strainer or cheesecloth, the whey would drip out and the yogurt would become thicker, like Greek-style yogurt,” Fletcher says. But if the yogurt is just sitting in its container (like in your fridge), the whey will pool up at the top, since it’s lighter than the yogurt.
You’re most likely to get leftover liquid from regular (read: non-Greek) yogurt that’s free of added stabilizers or thickeners (like guar gum, gelatin, pectin, or carrageenan), Fletcher points out. Since Greek yogurt has already been strained to be ultrathick, it contains less whey to begin with. And stabilizing or thickening ingredients prevent whey from separating out, so they typically yield yogurts with a more uniform texture. Larger containers will likely have more liquid than single-serve cups, just because they tend to sit in your fridge for longer after you open them.
Okay, so all this just means that there’s a perfectly normal reason for that liquid to be pooling on top of your yogurt. So what—if anything—should you do about it?
Since the whey came from the yogurt, the easiest thing to do is just stir it back in, Sauceda says. This might make the yogurt consistency just a little thinner, but if you stir well, you probably won’t notice too much of a difference.
And there’s good reason to do so. “There’s tons of nutritional value in whey,” says Sauceda. “It’s rich in protein, and protein helps you stay full and satisfied.” Whey also serves up minerals like calcium, potassium, phosphorus, copper, and zinc, along with the beneficial probiotics found in the more solid part of the yogurt, per a Journal of Dairy Science review.
Fletcher and Sauceda are usually stir-it-back-in people. But sometimes Fletcher will pour off the excess liquid if she’s using her yogurt to make a dip and wants the consistency to be a little thicker. In that case, you could hold onto the whey for another use if you don’t feel great about dumping it down the sink. “You can freeze the whey in ice cube trays and add individual cubes to a smoothie for a little extra protein,” Sauceda suggests. Getting rid of the whey won’t mess with your yogurt, but it might decrease the nutritional content by just a smidge, she points out.
As for how to avoid getting the watery stuff in the first place? It’s totally normal for whey to pool up in yogurt, so there’s not much you can do to prevent it, say Fletcher and Sauceda.
You can, however, rest assured that the watery stuff isn’t compromising the safety of your snack: Whey rising to the top has nothing to do with spoilage. As for what could be a sign of a food safety issue? Any changes in color, an off smell, or a bad taste, can indicate your yogurt has gone bad, says the USDA. If you notice any of that, then it’s time to toss your container.