I brewed a 10-gallon batch of pilsner in June. We drank all but half a kegs worth in August. I rotated the beers on tap and set aside the keg to let if lager a little bit more. Well, I ended up needing the space in my fermentation/lager chamber and set the pilz keg next to the cooler in the garage. I meant to bring the keg inside, but forgot. I didn’t realize my mistake until a week later and just figured that any damage from the heat was already done. It sat in the hot garage for at least 6 weeks until a week ago, when I had enough room to cool it back down and I moved it to my kegerator.
The beer: It tastes fine, but I am noticing a different mouth-feel and a slight sourness. I think the beer tastes wonderful, but it doesn’t taste like a pilsner anymore, it now tastes more like a Belgian.
I don’t know enough about lacto/brett, but would letting the beer warm up, speed up any lacto/brett growth and result in the new flavors? Or do you think the change in flavor is simply a result of the hot temps?