I've only recently been introduced to the glory of sour beers, and I love them. As a club, we're going to be brewing a sour beer to be aged in oak for years to come, so I was curious to see some questions on here about sour mashes.

It sounds like the process is still similar, you're collecting bacteria and wild yeasts (we'll be using a commercially available combo pack), but is there an inherent value to doing this pre-boil? Is this simply a way of getting the sour you want and then stopping the process?

4 Answers 4


Yes, the reason for doing this pre-boil is so you can achieve the sourness you want, then kill the bacteria. That way it doesn't interfere with your yeast and let the sourness get out of control.


Check out BYO's article great article on the difference between making your beer sour during the boil or making it sour during fermentation. In researching a Flanders Red, I found an article from Raj Apt, How to Make Sour Beer. The BJCP Style 17 also has good reference data.

IMHO, most of the really tasty sour beers are getting the sour profile during fermentation with "bugs", e.g. Brettanomyces, Lactobaccillus, etc. The base beer is fairly traditional with lactic acid (from bacteria) providing the sour profile.

To your point, there are some great combo yeast and bacteria packs from White Labs and Wyeast. There also some boutique vendors like East Coast Yeast that are making stellar yeast and bacteria products.

Also check out Jamil's book, Brewing Classic Styles which has some good articles on sour and lambiac styles.


I can't think of any Belgian sour beers that are produced using a sour mash. As far as I can recall, they all use bacteria in the fermenter to achieve it. Of course, that's not to say that you can't use a sour mash to produce a sour beer. I think that there's a Kentucky common that does that.


I know that some of the souring organisms prefer a more acid environment (lower pH) than the typical wort can provide. I think you can get a similar effect in a shorter time by using acidulated malt. I don't know what sort of flavor differences that you'd see when doing that, though. Presumably the sour mash will produce a much more complex set of compounds than simply adding the acid malt.

Sour Mash wiki article

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