Sour beer

Making sour beer doesn't need to be complicated!

Lactobacillus plantarum is a game-changer for making sour beer. It's super clean, it produces a robust sourness at room temperature, and it's extremely hop-sensitive, which can be advantageous.

Modern methods for fast souring

These techniques are a good alternative to the antiquated kettle souring method.

Co-sour method

1. Make unhopped wort.
2. Chill, transfer to fermenter, and aerate as normal.
3. Pitch Lactobacillus plantarum and the yeast of your choice.
4. Ferment as normal, at 65°F (18°C) or higher.
5. Optional/recommended add hops when it reaches the desired sourness. (Dry hops or hop tea)
6. Package as normal.

Post-sour method

Same as co-souring, except pitch the Lactobacillus plantarum after fermentation is about 30-50% completed, normally about 1-2 days of yeast activity. Using a starter for the Lacto is recommended.

Post-souring is designed to maximize yeast flavor. It's great if you want to use an estery yeast like WLP644 (Sacc Trois) for example, which adds a nice tropical pineapple & mango profile.

Frequently asked questions

Q: Won't the Lacto ruin my equipment or contaminate my other beers?
A: No. Normal cleaning and sanitation procedures easily remove L. plantarum. Furthermore, L. plantarum is extremely hop-sensitive and will not sour your clean beers with hops, even if you directly add it. These techniques actually have LESS risk overall of contamination compared to kettle souring.

Being so hop sensitive makes it so that even with inadequate cleaning, it won't grow or make acid in a hopped beer. This eases concerns about potentially contaminating other beers. Avoiding having wort sitting in the kettle for days actually results in less risk of contamination.

Using more hop-tolerant species like L. brevis may also lead to concerns for contamination if you don't kill it and don't clean properly. However, anecdotes suggest that proper cleaning is not difficult and cross-contamination does not necessarily occur while using one set of equipment even for Brett, Pedio, and other wild microbes.

Q: Where do I get L. plantarum?
A: Several sources are readily available in the US:

• Swanson's L. plantarum capsules can be purchased online (Amazon).
• GoodBelly liquid probiotic is available in stores.
• Renew Life Ultimate Flora are both widely available in stores. Bonus points if you find a store that keeps it refrigerated.
• Lallemand offers pure L. plantarum as WildBrew Sour Pitch (The Beverage People).
• Other yeast labs sell Lacto blends of L. plantarum mixed with other species, often L. brevis (use these blends at your own risk because they are more hop-tolerant).

Store the Lacto in the refrigerator. The dry capsules will last a very long time.

Q: Do I need to make a starter for the Lacto?
A: It's not needed, however if you use the post-souring process, I do recommend a starter. Starter procedure: After chilling, drain about 200-500mL wort into a sanitized jar. Add the Lacto and a few grams of calcium carbonate. Cover and let sit at room temp. When pitching, decant it off of the calcium carbonate (you don't want the chalk in your beer).

Q: How much Lacto do I pitch?
A: Pitch rate isn't very important. Feel free to use 1-2 capsules or a few ounces of GoodBelly in 5 gallons.

Q: Won't it take months to sour?
A: No. L. plantarum sours quickly (within a couple days) anywhere in the range of 65-100°F (18-37°C). It will finish in the same timeframe as non-sour beer. I've gone from grain to packaging in 3 days. It can take 1-2 weeks to reach maximum sourness if no hops are added, even though the large majority of souring occurs in the first few days.

Q: How long should I boil the wort?
A: Boiling is entirely optional since we don't need to isomerize alpha acids in hops. Mash temperature pasteurizes the wort.

Q: What amount of hops should I add?
A: Anywhere from 0.5 oz to 1 oz per 5 gallons adds a nice hop character (in my opinion) and completely inhibits further souring.

Q: Do the bacteria add flavor?
A: Generally, yes, depending on the source of L. plantarum you use. Frequently the Lacto contributes a nice lemony citrus tartness, notes of berry and melon, and possibly some slight funk. Adding hops after reaching desired sourness will reduce the funk complexity. The Renew Life blend probably adds more flavor than a single species culture and it also creates a more funky profile when used at high temperature (e.g. when souring with kveik at 95°F [35°C]).

Most of the desirable flavor from bacteria is expressed within a few days (e.g. lemony citrus, berry, peach, melon, tea, smoke, yogurt, etc). If you leave it go uninhibited, there will indeed be a bit more "complexity" that develops within a couple weeks. A lot of that extra complexity comes from isovaleric acid production, and this might not be desirable to you (I don't particularly like it). Extended aging beyond a couple weeks doesn't do anything. Adding hops seems to prevent the isovaleric acid production.

Isovaleric acid (or production of any other unwanted compounds) isn't an issue if you use Brett because Brett just eats anything undesirable and poops out awesomeness.

Q: Will it continue to sour if I don't add hops?
A: Yes, possibly, but Lacto's ability to produce acid is self-limiting. Normally this species finishes around pH 3.1-3.3.

Q: What is hop tea?
A: Boil the hops for 5-10 minutes in 300-500mL of chlorine-free water. Dump it into your batch. If you add it at bottling, strain through a hop sock. Added bitterness will be minimal.

Q: Do I need a pH meter?
A: Not really. If you're inclined to stop the souring before it finishes naturally, you can do it by taste. However, pH meter is a good investment for all-grain brewing, as well as monitoring the Lactobacillus fermention. Keep in mind titratable acidity (TA) is the measurement that best correlates with sour taste (unlike pH).

Q: Do I need to pre-acidify the wort?
A: Nope!

Q: Should I pitch more yeast than normal, or add yeast at bottling?
A: Nope!

Q: Can I use yeast cake from a previous batch?
A: Only if there were absolutely no hops in the batch from which you harvested it.

Q: Will the beer benefit from aging?
A: Nope!

Q: Is this beer probiotic?
A: Yes! Hops do not kill the bacteria (they are bacteriostatic, not bactericidal).

Q: Can I use a culture that doesn't have L. plantarum?
A: No.

Comparison with other souring methods

Kettle souring is a relic from back when brewers were sour mashing or using grain (wild microbes) for souring wort. In that case it made sense to kill the wild culture because there may have been any number of undesirable bacteria and/or yeast species that might cause problems.

Pre-sour (AKA kettle sour)	Co-sour and Post-sour
Longer brewing/fermentation process and two separate brew days. Higher risk of contamination. Pre-acidification recommended. Requires high bacteria pitch rate. Kills the bacteria (if you boil/pasteurize after souring). Removes most of the bacterial flavor (if you boil/pasteurize after souring). Generally requires higher yeast pitch rate. Mutes yeast flavor almost entirely. Precludes low oxygen brewing. Allows use of a larger variety of bacteria cultures.	Shorter brewing/fermentation process. Single brew day. Lower risk of contamination. No pre-acidification needed. Low bacteria pitch rate allowable. Lets the bacteria live. More flavor from the bacteria. Normal yeast pitch rate. Allows normal yeast flavor expression. Allows low oxygen brewing. Requires Lactobacillus plantarum (unless using kveik, maybe).
Allows control over the hop rate. Allows control over the sourness. Can make delicious beer.

Lactic Acid Yeast
Normal process length, contamination risk, and pitch rate. Requires no bacteria. Allows low oxygen brewing. Limited flavor options from the few cultures that are available. No control over the level of sourness.

Modern methods for fast souring plus Brettanomyces

• Make highly fermentable unhopped wort.... 70% pale malt, 30% wheat malt, mashed around 145-150°F (62-65°C) for 2 hours. Target OG about 1.040.
• Water: RO with CaCl₂ for around 60ppm chloride, with lactic acid to hit mash pH 5.4.
• Boil is optional, but recommended, 60 minutes.
• Chill.
• Pull off about 300-500mL to make a Lacto starter: add a little chalk and L. plantarum; let sit at room temp.
• Pitch WLP644 from a vitality starter.
• Pitch Brett from a starter (this takes 1-2 weeks). Wyeast Brett Lambicus (5526) is excellent!
• Let it ferment around 70°F (21°C), allowing free rise.
• After 24-48 hours pitch the Lacto starter, decanting off the chalk.
• Dry hop or hop tea is optional but recommended when it reaches the sourness level you want (a few days). Don't overdo it, 0.5-0.75oz per 5 gal Czech Saaz or Amarillo is great.
• Add glucoamylase enzyme to help purge oxygen when you add hops, or add it when pitching Lacto if you don't plan to add hops.

It'll be sour, funky, and ready to bottle within a few weeks, with gravity around 1.000 (yay glucoamylase).

For variety, add Brett strains, mixed culture blends, or dreg cultures directly to bottles. A few drops of slurry from a yeast bank works perfectly well. With only 3 Brett cultures you can make 8 different beers from one batch this way.

Funky character from the bottling stains typically becomes apparent within 2 months but starts to peak around 3-6 months.

.... Perhaps we could skip the Brett in primary and just add it at bottling. It seems like this would be an option as long as the enzyme gets the gravity low enough. This might avoid the possibility of THP formation, which would be a huge plus.

The main downside is that it won't be ready to drink as quickly. Also it won't be as consistent from bottle to bottle.

Recipes

Almost none of the traditional styles have fruit: Berliner, Gose, Saison, Kvass, Lambic, Gueuze, Flanders Red, Oud Bruin, Lictenhainer, Faro... Only fruit lambics traditionally have fruit, and they aren't traditionally dessert sweet like Lindemanns pasteurized series. These commercial fruit smoothies and sours with all kinds of unusual flavor adjuncts (like cucumber sushi curry) are unique American creations, often improperly labeled with the traditional style names.

The RenewLife bacteria blend adds a lot of flavor and there are many very flavorful fruity yeast strains (including Brett) that can be used with the post-sour method. For example, WLP644 + WY5526 + Lacto makes a sour pineapple + mango + cherry beer with that indescribable Brett character and it's amazing. It also develops a very nice horseblanket if you allow it to age.

WLP644 post-soured makes a great beer without the Brett, and doesn't need temperature control so it's very newbie-friendly! There are plenty of other fruity flavorful yeasts as well.

Hoppy sours can be quite good. Amarillo is popular for good reason. Czech Saaz works really well too.

Also, malt can obviously add plenty of flavor. Flanders Red is one example. The Munich, crystal, and small amounts of Special B malt and oak really complement the cherry Brett character and mix of lactic sourness and slight acetic tang. Grab a bottle of Duchesse de Bourgogne or Rodenbach Grand Cru and give either of those a try. Plenty of other malts are good for adding dimension too, beyond what I've mentioned.

In a gose, the water profile adds a refreshing minerality. Coriander is traditional, or hops can be used for flavoring in non-traditional spin on this style.

Gruit is flavored with interesting herbs and probably does well with souring.

These souring methods I've presented allow easy production of complex beers that don't need fruit or any other adjuncts... Not one-note kettle sours. Of course, if you do like fruit beer, it's probably best to make sour beer as the base since most fruits are naturally sour so it better complements the fruit character.

Increasing or decreasing sourness

Coming soon.

Modern blending program

Coming soon.

Additional techniques and tips

• https://www.brunwater.com/articles/add-depth-to-your-sours

See also

• Milk the Funk is a great resource and explains modern methods of mixed fermentation.
• The thread on homebrewtalk.com discussing modern fast souring with Lactobacillus.
• Check out Milk the Funk "The Podcast", especially the "Kettle Sour" and the "Lactobacillus" podcasts: http://www.milkthefunk.live or on Itunes or your favorite podcast service.