I would hate to not be a crowd pleaser so I've tried to distill some new thoughts about sour mashing and give some specific thoughts on how it can be implemented in various styles, modification of styles and fake versions of sours by way of using sour mashing instead of the typically very long aging process. As always, I do want to point out that when it comes to sour styles you will not produce as great of a product by sour mashing as you will by going the traditional route but I do think you can produce great beers that trade off a short time frame and less risk of infecting your equipment for the benefits of aging.
General additional thoughts about sour mashing (in no particular order)
1. First off, one thing to remember about sour mashing, although it is true of any souring process, is that when you let anything other than yeast consume the sugars in your wort/mash, unless it also happens to be an alcohol-producing strain of lacto you are going to lose some alcohol potential in your beer because the lacto in your sour mash is eating sugar to convert into acids. This is at least part of the reason why most sour styles, at least traditional styles, were very low in ABV.
Of course, the longer you let the sour mash go the more sugar gets eaten and the less is left to be converted into sugar. I have not tested to figure out how fast lacto chews through sugar to know when you have sugar-less wort. (That would be an interesting experiment but one I likely will never do.) If getting your ABV to a specific number is very important to you I would suggest doing a pre-boil gravity test and be prepared to add some DME or other sugar source to the boil to compensate for the sugar-turned-acid. Personally I don't worry about it but if I was a more diligent brewer I'm sure I would.
2. Personally my enjoyment of sour beers runs in the oud bruin and lambic range. I do not enjoy Flanders red -- the balsamic vinegar taste is unappealing to me -- and I think very sour beers, such as La Folie, are overly sour. Keep that in mind when I give recommendations on what portion of the wort to sour for different styles. You may be dabbling in soured beers and want less or you may be hardcore about your sours and want to go further down the path. The great thing about doing sour mashes is that you don't have to worry about how high the ABV will be, how hoppy it is, what the pre-boil wort pH is, etc. that normally affecting souring beers. (E.g. souring high alcohol beers can be difficult because lacto and sometimes pedio do not work or struggle to work in high alcohol beer.)
3. Sour mashing is an artform, not a science. Although some of you may have ways of keeping very specific temperatures (e.g. using hot pads or placing it by a furnace) there's always going to be some unpredictability in how aggressive the strain(s) of lacto and whatever else you have in there. For this reason I find it really important to determine the percentage of total wort you want to sour -- the more wort gets soured the more sour it will be (obviously) -- and from there judge the sourness by your nose. It requires you to do two or three sour mashes to figure out how strong of a smell relates to how sour the wort is. I do not recommend drinking your sour mash pre-boil because it probably has enterobacter like e. coli and other stuff that could make you sick. Depending on how warm you can keep your sour mash I find that three days is about the maximum I want to go on a sour mash. If I kept really warm temperatures (around 115F-130F) steadily I would probably do one, maybe two days.
4. Do not fear the smell of the sour mash unless it should be feared. A correct sour mash, at least the partial sour mash I do, should smell somewhere in the vicinity of rotten creamed corn. It should have a slightly sour milky smell and of course smell some like wort (hence the rotten creamed corn). It is a powerful smell when the sour mash gets very sour. It will go into the boil kettle with that smell. It will go into the fermenter with some of that smell. It will even ferment with some of it. Once fermentation is done it is gone. The beer is just tart/sour.
If your sour mash smells like vomit, shit, rotting trash, etc. then something has gone wrong. Lactobacillus did not win and whatever you have going on might be really nasty, even after being fermented. I believe doing the sour mash with the whole mash and all the grains increases the chance of a really nasty sour mash gone wrong. I'm not sure why and that is completely baseless speculation. I just know I have never had a problem with my process. If you get these bad bodily fluid smells on your sour mash, proceed at your own peril.
5. Sour mashing produces a fairly one dimensional kind of souring. It produces primarily lactic acid but by nature of being a wild process you get some other stuff going on that makes it a little more natural than adding food grade lactic acid to your boil kettle or fermented beer. It is this one dimensional sourness that makes a sour mashed-fake sour beer less interesting, less complex and less flavorful than a traditionally soured beer where you might have lacto, pedio and brett all contributing something different.
There are some additional steps you can take to improve the complexity of a sour mashed beer. To get some of that acetic acid flavor from brett and pedio you can add a very small amount of distilled white vinegar to the beer. I think I would go half a tablespoon per gallon, but again your preference for that sour taste may vary. (This is the rate I used for my fake oud bruin.) If you really wanted to get that flanders red-balsamic vinegar taste you could experiment with adding balsamic vinegar instead of white vinegar. To get brett flavors the best way would be to pitch brett in your beer as a secondary fermentation, but if you are sour mashing for speed you can do an all-brett beer and get a small amount of brett flavor. Since brett likes an acidic environment, a sour mashed beer is the perfect place to let brett be the primary fermentation yeast. Research indicates all brett beers can take around eight weeks for stable FG to be achieved so although it isn't saccharomyces fast it's also not the year or more brett can take as a secondary fermenting yeast. The benefit you get with this route, along with the shorten time, is that the sour mash will thin out the beer so when brett chews through the remaining sugar you get a dryer mouthfeel, which is typical of sour beers. It won't be as dry as a traditionally soured beer but it will get you close.
This is the process I used for the brett aged pale ale portion of the fake oud bruin currently in the works. Having tasted that portion (as I discuss in the two month update -- part 6) it is a complex and sour beer. Getting the vinegar, sour mash and brett primary fermentation together has created a sour beer that I think could go head to head against a similar beer traditionally soured.
Taking a distinctly American brewing approach, you can also use specialty grains to add complexity to the beer. Crystal malts may be unnecessary but using multiple base grains (pale malt, pilsner, vienna and munich) can add complexity as well as specialty grains like aromatic, special B, toasted, biscuit, roasted barley, chocolate, carafa, black malt, etc. Small amounts are all it takes to introduce a complex flavor into the beer. The darker the grain the less you will want to use so that the bolder grain flavor does not conflict or cover up the sourness. You should also go with 2-4 specialty malts for this purpose to avoid adding so many grains you develop a muted specialty grain flavor from having too many flavors overlap.
6. Don't assume that sour mashing is only useful for making fake versions of oud bruins, Flanders reds, lambics, berliner weisse, Kentucky common, old ales, etc. You can also adapt non-sour beer styles to souring without having to commit six months to years to see if it turns out ok. Just like La Folie is a fairly standard brown ale turned into an acetic acid powerhouse, you can also take a regular beer and sour the piss out of it. If you were so inclined -- and I am not -- to sour an IIPA to hell you could do it with a sour mash and still retain all the fresh hop aroma and flavor. I don't know why you would want to do it but the benefit of homebrewing is having beer to your specifications.
Ok, moving on...
Adapting sour mashes to beer styles
I am going to knock out the most obvious -- sour styles -- first before moving on to other styles.
1. Oud bruin - I've covered this extensively in the fake oud bruin project (see the menu on the right) and briefly above. I sour mashed half the aged pale ale portion of my blended oud bruin, borrowing Petrus' blending process discussed in Wild Brews, so it would be a total of 10% of the batch. After boiling I added half a tablespoon of white vinegar to the aged pale portion and fermented with brett brux taken from Orval dregs. It will then be blended with a brown ale with Belgian specialty malts and fermented with a Belgian saccharomyces strain. You can follow this process or do a single wort with a typical oud bruin grain bill and sour a portion of the wort and take whatever additional steps you see fit.
2. Flanders red - not a favorite of mine so not much to say here. I would take the same approach as the oud bruin, either the blended or single batch process, but add more vinegar. I would suggest maybe going 20% or more for the sour mash if you do not sour mash the whole mash. You may want to taste it before bottling/kegging to see if it is sour enough and acetic enough. You can always blend more vinegar into the beer at this time as distilled vinegar is sterile and will not hurt your beer (unless you drop the ph so low the yeast cannot bottle condition and carbonate). Experiment with adding a little balsamic vinegar if you are a big fan of that flavor in your Flanders reds.
3. Kriek - I think the cherry lambic-like beer I made in my sour mash-fake kriek (as others have done) easily lends itself to the sour mash process. Cherries will add additional tartness and complexity. Ferment with a good Belgian strain to get some good Belgian ester flavor in it. Alternatively you can primary ferment with brett but I suspect adding additional sugars (the cherries) might get you into the very long brett secondary fermentation. I am not sure because I have not tried. You could blend a saccharomyces fermented sour mashed cherry beer with a brett primary fermented beer to get some brett character in it. Depending on how sour you want the beer you could go to 20, maybe even 25% sour mashed to get the beer deliciously tart without being mouth puckeringly sour. Go more if you want a really sour kriek-style beer.
4. Lambic - I broke lambic out separately from the kriek because I don't think you would be as happy trying to replicate a straight lambic or gueuze by just the sour mash. Lambic really needs that brett and sour interaction. Without the brett you just have a sour wheat beer. You could try doing a brett primary fermentation and add a small amount of vinegar if you find it necessary, although acetic acid is not strongly represented in most lambics. I am not sure you would get the strong brett flavor you need for lambic. Nor would you get the really complex aged flavor that is the hallmark of lambic. I don't even think faro would work but it might be worth a try. If not kriek I would try other fruits like raspberries and other similar berries, currants, apricots, wine grapes, etc. Similarly 20-25% sour mash unless you want it more sour.
5. Old ale - I don't think of old ale being sour so much as brett, so I would say if you want to do this style you probably need to look at investing the many months or years necessary to produce a good old ale to get the brett flavors out there, but if you are going to do that you might as well just pitch lacto and/or pedio along with the brett. I don't think brett primary fermentation would give you sufficient brett character but it is possible to get something like an old ale through a sour mash and brett primary fermentation. Souring may be sufficient at 10-15% but your taste may drive it higher.
6. Berliner weisse - here's a style begging for a sour mash. Since it's basically a wheat beer fermented with neutral ale yeast and lacto, you don't have to get very far from the actual process. In the interests of fairness I can say I have never made a BW so I don't know exactly what percentage of sour mash would be effective but I would venture a guess that you could go 25-50% depending on how tart you want it.
7. Kentucky common - a mostly dead native US style that was sour on a thirst quenching scale also easily lends itself to the sour mash style (as you can imagine, it is similar to sour mash whiskey of the same region). Sour mashing could be done in the 25-50% range as your sourness desires. Since it is typically a session beer you may not want to go too high on the souring but it's your beer and you should make what you enjoy.
Moving into styles that have easily lent themselves to sour mashing...
8. Stout/porter - specifically Irish stouts. Guiness is made, at least it is widely believed, by adding soured Guiness to a new batch to give it that acidic bite. It is definitely proof that you can do sour with dark malts in the right context. The acid is fairly minimal in this beer compared to sour beers above so I would only go 5-10%. Sweeter stout styles, such as oatmeal, milk/cream and foreign export would likely not improve from a sour addition. I have similar opinions of imperial stouts because the bitterness from hops usually does not pair well with sourness (although it does with brett).
On the other hand, English stouts (and porters) traditionally were thought to have some old/brett or sour character over time so some sourness might add something unique to these beers. Again 5-15% should be enough to give it character without losing the stout flavor and mouthfeel. Belgian stouts could also be a good target for experimenting with a small sour addition.
9. Wit - it is believed that old school wits (pre-Hoegaarden) had a sour character that balanced out the coriander/orange peel (perhaps the seasoning started being added to cover up the sour flavor??) preventing that overly sweet coriander/soup flavor that many wits have. (I believe this is discussed in Brewing With Wheat.) Wits have sort of a lemonade flavor so some sourness would seem to add to the refreshing characteristic of this beer. You might want to start off light at 5-10% and go higher if you find the sourness lacking.
10. Saison - saison is kind of like the meatloaf/stew/etc. of beers. You just add whatever you have together and you get something pretty good out of it. It's a style that easily lends to experimentation and extreme variation. Although brett saisons are all the rage -- and I thoroughly enjoy them -- there's no reason to believe that somewhere across the northern French farmlands some saisons got sour without a heavy brett addition. A mild sour mash at 5-10% could add some refreshing complexity and thirst quenching appeal without making it obviously sour. You could go increasingly higher (maybe as much as 50% or more) to create a truly sour saison.
A very sour saison would probably need a more simplistic recipe so those things commonly tossed in saisons for unique flavor don't clash. Rye is a very strong and noticeable flavor that may not fit with sourness (although there are old school sour-rye beers like kvass). High IBUs and/or dry hopping may not fit with sour in this beer. Spices like cinnamon, nutmeg, ginger and the like may not be a good fit with sour but coriander, pepper, seeds of paradise and other fruity or spicy spices may be a better fit. Dark adjuncts like molasses, brown sugar, treacle, etc. also may not be a good fit. (But I could be wrong.)
11. Brown ales - I know oud bruins are sour brown ales, but when I think of oud bruins I think of a brown ale with Belgian specialty grains and/or Belgian yeast esters. Other brown ales, such as English brown ales and American Brown ales (provided they are not overly hopped), can also be soured -- such as La Folie. Depending on the sour profile you are interested in you could sour mash to whatever percentage you want (even up to 100%) and you could also do a brett primary fermentation if so desired. Brown ales are easy base beers for sours because they tend to be sessionable and/or neutral beers. Not too malty, not too hoppy, not to high in alcohol, etc. Because milds also are of the same type as English milds (if not synonymous to English brown ales) they could also be soured. While we're at it, the same could be said for red ales. Since they are extremely sessionable beers I would aim to sour to add some tartness and thirst quenching appeal rather than an out and out sour flavor, so 5-15% would be sufficient.
Now on to some less frequently soured beers...
12. All other Belgian beers - included here are tripels, dubbels, quads, Belgian strong ales and the like. All of these beers, generally low in hops but with a solid malt backbone can be altered into sour beers. For people who find these beers too malty or not bitter enough, adding some sour can drive down the maltiness and add acidity in a way these people may find appealing. I would look to sour no more than 5-25% myself (although I doubt I would personally sour any of these) but others may chose to go higher.
13. Blond ales - this can include both US and Belgian blond ales. Kolsch and California commons can also be added here. These beers should all fall into the sessionable category and as good lawnmower beers a little sourness could give it that lemonade-like thirst quenching appeal. I would go no more than 5-15% but if you like a really tart beer maybe as much as 25%. Since these beers are not very malty too much souring will thin the beer down to a very watery mouthfeel, especially if you use adjuncts.
14. Scottish ales - I hear some people using a little sourness to add tartness and complexity to these beers. Personally I don't think the smoky flavor often produced by Scottish yeasts and/or peat malt lends itself to much sourness so if any souring is to be done I would think 5-10% would be enough to add complexity and tartness without interfering with other flavors.
Now for some general thoughts on beer styles I would not try to sour:
- Anything hoppy -- I've made the comments above but hops contribute bitterness to beer so adding sour seems to make it too unbalanced. It also seems to clash with hop flavor. For that reason, pale ales, IPAs and their variants, and all "Imperial" beers are out.
- Hefeweizen/dunkelweizen/similar wheat beers -- I have a hard time imagining banana/clove and sour go together. My thought here is that any attempt to sour these beers is going to make something like a Berliner weisse, so you might as well make a BW. I think an American wheat would be too hoppy to be well soured.
- Black ales -- I think black ales (e.g. 1554) would be too roasty for souring but on the other hand stouts and porters tend to have roasty flavors and sour works ok with some of those beers. I think of black ales as a beer that relies on the roast differently but I could be wrong and it could be a nicely soured beer.
- Any lager style -- in my opinion lagers are not beers well suited for souring because lagers rely on that crisp, clean flavor to balance the malt and hop flavors. I think sour would create imbalance in the flavor profile but since I am not a lager expert I'm sure there are people out there who have soured lagers and created delicious beers.