How To Brew Sour Beer

Sour beer is a bit of an acquired taste, but with the explosive growth of craft beer, like IPAs and their sour variants, more and more craft beer drinkers are looking to sour beers as an option. 

This is especially true for restaurants, where sour beers pair well with foods containing salty meat, citrus, tangy cheeses, and egg dishes with creamy sauces.

Here’s what you should know about brewing sour beer.

Step One: Understand Your Fermenting Options

There are four major options for fermenting sour beers.

Brettanomyces

Sometimes known simply as Brett, this is a common choice for sour brewing. Specific variants offer an incredible variety of flavors, ranging from fruits to hay, sometimes referred to as a “horse blanket” characteristic. 

Age has a heavy impact on how well this yeast strain performs, with fruity flavors being more common in shorter fermentation cycles and deeper, earthy tones emerging if fermentation keeps going.

This is a great yeast strain to start with if you’re not sure what to use. It’s affordable, widely available, and has enough variety for even professional breweries.

Lactobacillus and Pediococcus

These two bacteria strains are an alternative to using Brettanomyces yeast.

Lactobacillus is usually the better of the two strains, producing large amounts of lactic acid (a primary souring agent) in a comparatively short time. However, it’s also a little hard to use because it dies quickly in environments with too much isomerized alpha acid

That means you need to carefully test and regulate your brewing process if you want to use it.

Pediococcus, or pedio, is an easier-to-use alternative to lacto. It takes much longer to sour beer properly, but it tolerates harsh environments much better. 

However, this isn’t a good bacteria strain to use alone. Instead, it’s better to mix it with Brettanomyces to help get rid of any off-flavors.

Notably, pedio also tends to affect the consistency of beer while it’s processing things. It’s not rare to see a thick, almost rope-like consistency during the sour beer fermentation process, but this usually goes away naturally. 

It’s not a sign that anything is wrong, so don’t dump out your beer if you see that happening.

Open Fermentation

If you’re especially bold, you can try open fermentation for this beer style and use wild yeast strains present in the air around you. Open fermentation sometimes produces good beer strains, like those in Belgium, so it’s often worth experimenting with at least once or twice. 

Open fermentation is generally safe as long as you follow proper brewing protocols and ensure the final result meets industry standards.

Alternatively, this could lead to a foul beer that should go straight into the dump. There’s no way to predict what you’ll get with open fermentation until you try it, so go in without expectations and see what happens.

Step Two: Pick A Souring Method

Almost every style of beer will go sour eventually, especially if you keep fermenting it. The main reason for this is that all beer has at least some contamination from other ingredients, which will probably sour the final result.

In the old days, most people drank the beer before it got too sour, and that was that. However, people also noticed that some specific varieties of sour beer were good in their own right, ultimately leading to the standardized processes we know today.

There are two broad categories of souring methods: traditional and quick. 

Step Three (A): Traditional Souring

The standard method for souring beer uses yeast and bacteria, plus enough time to produce a specific drink.

Traditional souring methods usually start with aged hops, which give more room for yeast and bacteria to begin acting in the drink. 

After fermenting the drink regularly, the beers go into wood barrels with cultures of the right bacteria for sourness. Over time, this mix produces the sour beers that we’re seeking.

It can take several months to sour a beer properly, especially if you’re using pediococcus instead of lactobacillus. Many people wait six months, or even a year, before selling beers aged through this method.

Traditional souring agents work slowly enough that they probably won’t build up too much pressure after bottling. If you’re still concerned about that, you can filter or process your beer to end fermentation entirely.

Step Three (B): Quick Souring

Sometimes known as cheating, this process rapidly sours a beer without removing too many good flavors. Quick souring works best when making a lactobacillus-based beer but won’t work with the more complex flavors of Brettanomyces. There are three main ways to sour a drink quickly, and we’ll discuss all of them.

#1: Sour Mashing

Sour mashing follows the basic process for creating a mash, then allowing it to cool to about 115 degrees. You have a little wiggle room here, but try to get as close to 115 as possible. 

At this point, you can add lactobacillus cultures (or unmashed base grain, which often has lacto in it) and keep it at this mash temperature for up to four days.

While doing this, remove as much oxygen as possible and avoid any contact with the air. Otherwise, you could contaminate your beer with bacteria from the air, ruining the overall flavor.

Adding a large shot of cultures when you’re mashing won’t get the same full flavor as a long fermentation process, but many people won’t notice the difference as long as the drink is good. 

Correct temperature control can be challenging, though, so make sure you have the right equipment for it.

#2: Kettle Souring

The kettle souring process is fundamentally similar to sour mashing, but it takes place later in the process. Make your beer as usual until you get to your wort, cooling it to the same 115 degrees that we like. Add the lactobacillus culture, then flush it to help keep out airborne pests.

Start your boil once you reach the sourness you want. Try to keep the pH as close to 4.5 as you can, adding ingredients like lactic acid if necessary. This helps encourage lactobacillus to do their job while inhibiting the growth of bacteria.

#3: Add Acid Directly

Adding acid is considered cheating in some circles, if only because you’re changing the finished beer rather than brewing it sour. However, done well, this is a practical and efficient way to change the final sourness of your beverage.

All you need to do here is purchase a dose of lactic acid and mix it into your beer until you reach the exact sourness you want. Try to avoid overdoing this, but don’t be afraid to get creative with your ratios.

Picking a Beer to Brew

While experimenting is good, especially to die-hard home brewers, it often helps to start with some established beer styles. Fortunately, replicating these is relatively easy for experienced brewers.

Berliner Weisse

This German beer is a wheat beer; quite pale and has low amounts of bitterness and alcohol content. These beers tend to have a slightly tart and sour flavor, and many people add fruit flavors to enhance their natural characteristics. 

It’s easy to brew in small batches at home, and with so many small companies making it, there’s plenty of people to ask for help.

Flanders

Belgium’s Flanders-style ales are a mid-hued, moderately alcoholic drink low on the bitterness scale. Many of these have cherry, cocoa, and wood-like additional flavors, with the sourness as a distinctive quality.

Creating an excellent Flanders ale requires proper aging in barrels, so it’s hard to use some of the cheats described above with this drink. 

Amateurs can try it, but this is a better option for experienced brewers who want to try making something more involved than a basic Berliner Weisse.

Lambic

Lambic beers also have their origins in Belgium, probably due to the local bacterial cultures that helped make good sour beers. 

Lambics are arguably the most challenging sour beer to make because almost every step of the detailed process differs from how people make other beers. Here are some of the highlights:

  • Lambics go through an aggressive mashing process, rather than the gentler strategy most methods use
  • Lambics use well-aged hops instead of newer, fresher ones
  • Lambics boil several times longer than traditional beer
  • True lambics have open-air fermentation, which is a bit risky if you don’t know what mixed cultures are in your air

That last point is especially tricky because it means that where you decide to brew your beer will significantly impact its final flavor.

Most lambic beers age more than one year so they can develop a good flavor. This method works especially well in somewhat cooler climates that can have more bacteria strains in the air. Hot climates, even if they’re humid, may not lead to the same results.

Officially, “real” lambics only come from areas of Belgium close to the Zenne river valley, which produces the bacterial strains that truly started this beer-making style. 

Some people refer to lambic-style beers created elsewhere as Methode Traditionelle to help distinguish their point of origin.

Blended Drinks

Many people go one step further and create gueuzes, blends of lambic-style drinks whose components have different ages. Blending can create an incredibly complex array of flavors, especially if you add more fruit while fermenting to infuse the drink with a final flavor.

The main thing to remember here is that you can create some astoundingly diverse sour beers once you understand how to change the brewing process and create the perfect drink. This takes time and experimentation, but the results are generally worth it.

Sour Beer Vs. Wild Beer

Sour beers and wild beers, especially ales, have many similarities. That’s not surprising because all beer was originally wild beer, and it’s only relatively recently that we’ve been able to add specific strains of yeast and bacteria to get precisely reproducible complementary flavors.

Wild beers trend towards being sour, with lots of acetic and lactic acids that provide a distinct profile. They also tend to have lighter bodies, so it can be hard to tell them apart at first glance.

Despite these similarities, there are also a few differences worth noting. The biggest one is that wild beer is not necessarily sour. The conditions for creating a sour beer are relatively specific, and any one of several variables going wrong can stop a beer from souring in a standard timeframe.

As noted above, almost any beer will sour eventually. If that takes several extra years, it’s usually not worth it. Furthermore, it can be hard to reproduce an authentic flavor with a wild beer, which can be challenging if you want to sell it.

Remember, a drink can be both a sour beer and a wild beer. These aren’t mutually exclusive categories because one refers to the flavor while the other refers to the fermenting and development process. The distinction between them isn’t as significant as some people think.

Frequently Asked Questions

Here are some common questions that beer people have about how to brew sour beer.

Is Sour Beer Healthier?

No beer is healthy if you drink too much of it, but sour beers can be more nutritious than other strains. The key difference here is sour beers made with lactobacillus, which is the same thing that makes yogurt healthy. Sour beers that don’t use this bacteria strain won’t be quite as healthy.

In other words, many sour beers are healthier than traditional beers, but this isn’t universal.

Do Sour Beers Have Less Sugar?

Sour beers occasionally, but not always, have less sugar than other types of beer. One of the main reasons for this is that people often add small amounts of fruit and other sweet things while fermenting the drink, improving its flavor and increasing the amount of sugar in it.

Broadly, alcohol-by-volume correlates with the number of calories, and therefore sugar, in any beer. More grain means more sugar when fermenting, which affects the final calorie count.

Sweet-and-sour beers are relatively popular, but some people also minimize the additions to try and let the natural flavors shine through better. As always, the only way to know for sure is to check the drinks individually.

Are Sour Beers Expensive?

Many sour beers are more expensive than other drinks, which holds back a lot of the market growth. The rising popularity is helping with supply issues, but sour beer is still a comparatively small part of the market.

One of the biggest problems in the industry is how long it takes to mature high-quality sours. You can try to speed it along with the processes described above, but when you have to compete on quality, that’s not the best approach.

Alcohol is primarily a volume-based system where both time and space impose constraints on things. Every keg aging in a warehouse is a keg that’s not getting sold to customers, so you have to sell it at a higher price just to break even.

Sour beers can also have particularly bad flavors if they’re not brewed right. They don’t have as much margin as other beers, so they take even more care to make just right.

The result of all this is that sour beer will probably remain an expensive, low-volume drink for the foreseeable future. 

However, they’ll probably grab a somewhat more significant percentage of the market than they currently have. These are beers that focus on quality over quantity, which is why they can be such a treat when you make them yourself.

How Long Does Sour Beer Last?

Sour beer lasts longer than many other types of beer. Many varieties can continue aging in a bottle for several years, and it’s not unusual to see a sour beer last at least one year after bottling. Ultimately, no beer lasts forever, but they are a good choice if you want to keep something in storage for a while.

However, as with all beers, it’s often better to drink it sooner instead of later. Most beers taste great shortly after bottling, and it’s often easier to enjoy it right away rather than risk it turning flat over time.

Should I Put Sour Beer in the Fridge?

Sour beer usually stores best around 50 degrees Fahrenheit. If you need a fridge to reach that temperature, store it there.

However, many cellars and underground areas can reach this temperature with no additional refrigeration needed, so those are viable alternatives to active cooling.

Is Sour Beer Hard to Brew?

Sour beer is somewhat more complicated to brew than regular beer. Even if you’re cheating and adding lactic acid after brewing, you’ll need to get that ingredient, mix it in properly, and use the right tools to measure the level of acidity before you seal it up. 

In other words, it’s always harder to brew sour beer than regular beer, although not ridiculously so.

Brewing sour beer correctly may also require additional equipment, up to and including cooling tubs that have some exposure to open air. These can be hard to get in some areas, so many sour beers come from smaller breweries that can focus all of their attention on brewing it well.