Off flavor 17 days after kegging

[Tar and Feather'em]

Hey everybody, I've been kegging for a good while now and never had this pop up on me. My brew finished and I kegged and carbonated. First week or more it tasted great, then it started to build up a slight sour off flavor in the finish after 2 or so weeks? Not sure why, aging or the recipe, oxidation somehow? Anyone ever get this before?

Thanks for any help!

 

[Ozarks Mountain Brewery]

sour is usually from an infection, yeast can get infected and taste sour

 

[Nosybear]

Sour how? Yogurt sour or vinegar sour? Both are contamination, yogurt is lactobacillus, vinegar is acetobacter. Now the tricky part: Did you prime the beer with any sugar? If so, you may just be tasting the intrinsic tartness in the beer that was previously masked by the priming sugar. Or simple age might be bringing the tartness forward. This is the kind of telediagnosis that's difficult, think the Car Guys (RIP, Tom). There could be several things going on. Best sign of infection, unless it's a pure lactobacillus problem, is other off-flavors accompany the tartness.

 

[Tar and Feather'em]

More yogurt I would say. Not heavy and only in the finish. Didn't start off that way took about two or more weeks. No priming sugar either, this is a keg.

 

[Tar and Feather'em]

I wonder now if maybe a sucked up a little yeast transferring to the keg that turned over time? I did not secondary the brew but filtered it with a mesh bag as I was siphoning it into the keg.

 

[Nosybear]

Sucking up a bit of clean yeast wouldn't do it. Any other off-flavors? At this point, diacetyl would be a give-away of an infection.

 

[Tar and Feather'em]

Nope no other off flavor but the slight sour at the finish. The keg is kicked now so this apparently appeared at the end of the barrel. Maybe it just aged that way at the end?

 

[Nosybear]

Beer is naturally acidic - you could just be tasting the tartness of the beer! In fact, I find if the beer isn't a little tart, it's fairly lifeless and bland. I believe the wine tasting term for a wine with too little tartness is flabby.

 

[Ozarks Mountain Brewery]

using too much Lactic acid can cause a sour taste too

 

[PZ]

You mentioned filtering the beer through a mesh bag. Depending how you did it, you might have introduced some oxygen which would cause off flavors over time.

 

[Ozarks Mountain Brewery]

slightly mildewed bags too, just like sour smelling laundry, Ive had that happen dry hopping before

 

[Tar and Feather'em]

Well the bag is submerged so I doubt it is that but....

It may just be that it is a little tart but I think I might have found what it was. I popped open two more kegs and still the exact same taste. The glasses I have been using get rinsed before going in the freezer the chill (when it is real hot out) I think the glasses might have been funky haha! From the residual water freezing on them then sitting in therebecause I pour one in a glass that is in my kitchen cabinet and the taste is gone haha.

I am going to take notice to this as the time goes by. But if it turns out this is not the case how do I get the "tart" out of there? I don't really like it and it was not there in previous batches.