Kefir that smelled like vinegar!

[Shirelle]

I bought some bottled kefir for my son last week.....two days ago, I poured him some, and he didn't finish it, so I covered it and put it in the fridge. I just pulled it out and gave it to him to drink, and he brought me the cup to ask me for something else to drink. The cup REEKS like vinegar. Does that mean the kefir went bad? Is it going to make him sick?

[cobluegirl]

hmmm...milk kefir? I would think it woudl smell like sour milk...not vinegar..water kefir and kombucha will get a vinegary smell....did something maybe contaminate the cup?

it sounds bad...but I don't think he will get sick from it.

[AJP]

I doubt it will make him sick. I think the kefir culture naturally produces some acetic acid (the kind in vinegar), and yours probably continued to ferment and got that strong smell. If it had other stuff added to it (fruit, sweetener), that may have encouraged the particular organisms that make acetic acid, causing it to get out of balance.

[JaneS]

I think it just cultured some more due to warm temperatures. Mine gets pretty strong if I let it go too long.

That being said, since it was pasteurized milk kefir, I'd throw it out.