What causes additional whey separation in Greek yogurt?

I don’t know, but I eat a lot of Choboni and I’ve noticed the same thing.
It kind of grosses me out, to be honest.
I just assumed that it was because of the fruit, but you eat the plain kind…..
Things that make you go Hmmmmm.

I just figured that it’s like many other natural products, including cottage cheese and sour cream, that have an imperfect suspension of solids in finished product, which allows separation over time. Sour cream and cottage cheese both do this, too. I don’t pay it any attention, but I pour off any excess liquid before I use the product, then stir the remainder and use it with no adverse effects at all.

I suppose if it sat unused for longer and longer periods, then the separation may become more and more pronounced, too.

I just stir the whey back into the solids. As @CWOTUS said, it’s just a natural result of the process of the making cheese and other dairy products. Like buttermilk is the liquid left from making butter. It’s the nature of the milk curds and whey. (Little Miss Muffet)

Yep. I certainly drain off the extra liquid – if there is some, then stir it up. My question has to do with what is the possible explanation for the same brand of yogurt having no liquid (I mean none) most of the time, but having a ton of it sometimes.

I have even found the following: I purchased some with the expiration date of 10/26 from Whole Foods and some from another market with the same expiration. The ones from Whole Foods had no liquid, but the others did. This leads me to think that there is something else at work here. Either it’s temperature or handling or something. They both were packaged at the same time, so therefore have been sitting for the same amount of time.

My first response, as before, would be “imperfect homogenization”, followed by “variations in handling”, including how many times you have had the container opened, for how long, under what ambient conditions in your kitchen, what you have knowingly or unknowingly introduced into the container (whatever cutlery and spoons you used in it, and whatever was on the cutlery and spoons), and whatever variation in the operation of your refrigeration equipment also exists. Of course, there’s also the transportation to the store (and to your home) variables, plus whatever variables exist in the production facility (or facilities), too.

That’s a lot of variables to control for in less-than-laboratory conditions.

When I’m really concerned about the amount of separation, then I also give it a smell test. If it passes that and the amount of liquid separation isn’t objectionable, then I just use-as-is after pouring off the liquid and stirring.

I’ve had more liquid when I’ve left the container in my purse all day (instead of eating it for breakfast when I first got to work).

I’d buy into your temperature theory @tom_g.

I never know why it occurs, but it’s not just Greek yogurt… the fat free organic stonyfield farms yogurt sometimes separates, too. I’ve never looked to see if it’s more often when the expiration date is near, or whether it is worse with different flavors. Like Sunny2 and CWOTUS, I just stir it right back into where it came from.