Problemas com a Anderson Valley Oatmeal Stout

Oi Alexandre. Sorry but to give a good answer I will post in English. I believe your bottle was infected(maybe the bottle wasnt sterile before filling). Anderson Valley like almost all craft beers in the US is not pasteurized. I would be shocked if they did for the Brazil market since they are against the process stating it effects the flavor and also that they would have pasteurize the beer just for the small amounts shipped to Brazil. Regardless of pasterization, a sour flavor doesnt come with oxidation, light struck bottles, or heat exposure. I have drank many unpasteurized craftbeers unrefrigerated(some up to 10 years old) the most will happen is oxidation(all beer), loss of hop profile(mostly IPA and pale ales, loss of fruit flavors(fruitlambics).

Sean, my bottle really showed clear signs of contamination - not just the sour taste, but also a typical Brettanomyces aroma (4-ethyl phenol). No signs of oxidation, by the way (or they were not noticeable due to the sour taste). If the lack of pasteurization is not a probable cause, then I guess you must be right - there must have been a problem at the bottling. Thanks for your help, anyway!