Sour Taste in Bottled Beer

[nuthouse_brewing]

Just got my score sheet on a Special Bitter I had submitted to a competition and the judge noted that there was a slight sourness to the beer. Confused, I tried one that I had in the fridge and there is a distinct sour/cider note--not horrible, but noticeable. Still have it on tap and it tastes great with no defects.

The beer had been force carbonated in the keg and bottled with a beer gun. I am a stickler for sanitation and everything gets a bath in Star San--bottles, caps, beer gun, me. This appears to be the first time I have had this problem. Any ideas?

 

[microbusbrewery]

Cidery and sour are a little different to me. I'd normally associate cidery with too much simple adjunct sugar or an acetaldehyde issue, but I'd expect that to be an issue in both the kegged and bottles versions. If it truly is sour, it's probably lactic acid. Assuming it is, even though you say you're meticulous about sanitation, something isn't getting sanitized properly. Are you cleaning then sanitizing (e.g. bottles, beergun, beergun lines)? You can't sanitize what isn't clean. I'd break everything down including keg disconnects and thoroughly clean everything and replace your tubing if it's more than a few months old.

 

[nuthouse_brewing]

I am pretty thorough on both cleaning and sanitizing, but will just need to review procedures. Thanks for the response.