halacha - Does Sour Beer Require Certification?

This is my first question ever on this forum, so here it goes!

I am a big beer guy. My wife and I love trying different beers. IPAs are my favorite. My wife's favorite are 'sour beers'. A sour beer is not exactly a flavored beer according to my understanding. It is a type of beer that ferments using wild yeast to get in the mix, which produces its sour flavor (I don't know much about it).

I do know that regular unflavored beer does not require a hechsher. What about sour beers (the unflavored sour beers)?

Thanks!