Article

Sour Mashing

Soured beers are gaining popularity among beer lovers and brewers alike. There are several methods you can employ to create a soured beer. Simple techniques include adding lactic acid to your brewing water or including acidulated malt to your grain bill. More advanced techniques include adding either cultured lactic acid bacteria or Brettanomyces, a mixed lambic culture of Brettanomyces, Pediococcus and Lactobacillus or oaking the beer with unsanitized oak ingredients while the beer is in secondary stages of fermentation. The final technique in the homebrewer’s quiver would be performing a sour mash, which is what we will be discussing in this article.

The goal of a sour mash is to employ the work of Lactobacillus delbrueckii to a great extent while limiting the work of other critters such as fungi or bacteria like Acetobacter or Clostridium. You can accomplish this by pitching a live culture of Lactobacillus, by controlling the temperature of the mash and by limiting the oxygen introduced to the mash. Acetobacter, as the name implies, will produce acetic acid, the key acid in vinegar. Acetobacter will only play a significant role if the sour mash is incubated for an extended time period. You will know when Acetobacter has taken hold when the mash vessel, upon opening, has a cidery-like vinegar smell. While you would like to minimize the vinegar included in the mash, it will not spoil your attempts at creating a clean sour beer if kept in check.

Acetobacter needs oxygen and will only grow on the top of the mash. If you seal the top of the mash by laying some plastic wrap across the top, pushing all the air bubbles out in the process, then you can greatly decrease the opportunity for Acetobacter to act. Clostridium on the other hand produces butyric acid, which is a foul-smelling acid, faintly resembling my freshman year dorm, a mixture of rank locker room smell mixed with vomit. If Clostridium takes hold in the mashing vessel, it is rather apparent right away and make sure to keep away from significant others if you enjoy their company. I would advise dumping the mash if Clostridium takes hold. But some people seem to be okay adding this rank concoction to their beer stating that the odor can be boiled away. In general, a foul-smelling mash is going to yield a foul-smelling beer. A little “funk” in the mash is OK (some aromas will get scrubbed in the boil and fermentation), but too much and it should be discarded. Skimming the top of the mash can get rid of many off odors. A good sour mesh smells “cleanly” sour. L. delbrueckii produces lactic acid, an odorless acid that got its name because it is the spoiling agent in milk when lactose is broken down.

Before attempting a sour mash, you will need to get a pH meter and calibration kit, a thermometer and a small mash container that you can seal up tight. A small, insulated cooler will work in a pinch. This will also help regulate the temperature of the mash over the course of several days. If you have a space that can hold the temperature above 100 °F (38 °C) for several days, then you can also utilize a 1-gallon (3.8-L) jug or even smaller, depending on the size of your sour mash. One key to a good clean sour mash is that your container be filled right to the top for the incubation period.

So what type of beers might you utilize a sour mash for? Really the sky is the limit, but a short list of good examples would include, but not limited to Berliner weisse, lambic-styled beers, Flemish reds and browns, stouts, porters, summer ales, weizens, wits, saisons and the more obscure style, Kentucky common. The sour mash will add a nice twang to the beer if a moderate percentage of the total grain bill is added and a full pucker face if a large percentage of soured grains are added. Utilizing 5% of the total grist for the sour mash is generally the lowest end of spectrum. This is in the realm of using the sour mash for mash acidification. That means that if your recipe calls for 10 lbs. (4.5 kg) of grist then your sour mash would contain 0.5 lb. (0.23 kg) of your base grain.

The question on how much sour mash that one should add is really dependent on the brewing water you will be utilizing, the end pH of the sour mash, and the extent of sourness you are looking to achieve. The stronger the buffering capacity of your brewing water, the higher the carbonate levels, the more sour mash you will need to add to achieve your desired effects. A 10% sour mash using soft water may produce the same results as a 15% mash when hard water is utilized. Trial and error is really the only way a homebrewer will achieve their desired level of sourness. The end pH of the mash is also very important, especially to all-grain brewers because ideal mash pH should lie in the range of 5.2–5.4. Vermont Pub & Brewery’s Greg Noonan advises, “a two-day sour mash will give a better flavor but half the acidity of a three-day mash.” In acidified beers, the sour mash is stirred into the main mash to hit a proper mash pH. In sour beers made with a full sour mash (Kentucky commons, for example), the malts are mashed normally, then allowed to cool and sour. A brewer could also make a sour beer by stirring a large sour mash into the main mash after conversion has taken place. This would work well for moderately souring experimental beers. The percentage of mash that is soured will play the biggest role. Souring between 5–20% of the grain bill will give the beer anywhere from barely a touch of sourness to a nice twang. If you sour above 20% of the total grain bill, then you are entering true sour beer territory. Some homebrewers will sour mash upwards of 50% or more of their total grain bill. This quantity is ill-advised for anybody who doesn’t want a true pucker-up beer or anybody that suffers from acid-reflux problems.

For first time sour mashers I would recommend souring between 5–20% of the total dry grist. This will give you something to work with for your next sour mashing session. Begin the sour mashing process two to four days prior to brewing the entire batch. Calculate how much of your base malt needs to be soured. You can use crushed 2-row, 6-row, pale ale, or Pilsner malt. Begin by heating 1.25 qts. (1.18 L) of water for every 1.0 lb. (0.45 kg) of grain in the mash, up to a temperature of about 162 °F (72 °C). In a pot, slowly mix the water into the grains and stir thoroughly. Wrap the pot in a towel and let the mixture stand for 40 minutes. After the 40 minutes, heat the mash up to 170 °F (77 °C) and hold for 10 minutes. Gently pour the mash into the vessel it will be stored in for the next several days, introducing as little oxygen is possible to the mash while pouring. The less oxygen introduced during this process, the less chance there is for mash spoiling critters to take control. Cover tightly with plastic wrap making sure to expel any air bubbles trapped on top and cool the mash down to roughly 115 °F (46 °C).

Inoculating (pitching the critters) in the sour mash is the final critical choice in the sour mashing process. The simplest and most straightforward technique is to keep a handful of dry grains from the preceding mashing steps, either crushed or whole grains work. Simply toss in the grains when the temperature of the mash falls below 120 °F (49 °C). The grains already contain the bacteria L. delbrueckii in their husks. Another way would be to pitch a culture of live bacteria. Both Wyeast and White Labs have made Lactobacillus strains available to homebrewers, or you may be able to find live cultures in some health food stores as packaged yogurt culture. Again pitch the culture when the temperature falls below the 120 °F (49 °C) threshold. Reseal the vessel and place in a warm spot. The closer you can keep the mash to the 120 °F (49 °C) mark without going over, the better your Lactobacillus will fare and the less likely unwanted visitors will take control.

On brew day, pour the sour mash through a strainer or colander to separate the grains from the liquid and add the sour liquid directly to the boil; or, if biological acidification is your goal, then add the sour mash to the main mash making sure the mash pH doesn’t fall below the 5.2 threshold. Begin by mashing the grains as normal in your mash tun. You will want to heat the sour mash up to your first rest temperature to avoid any complications with volume and temperature of strike water to add. If your goal is to make a sour beer, then you can add more of the sour mash just after the saccharification rest but before lautering in order to raise the sour intensity.

Turbin Mashing

Turbid mashing is a method that is still practiced in a few smaller lambic breweries in Belgium, such as Cantillon. If you have interest in brewing lambic-styled beers, wit beers, low-gravity or small session beers — or you just want to try an experiment — a turbid mash may push your beer to the next level.

Why Turbid Mash?

Turbid mashing is time-consuming, requires some specialized equipment and produces cloudy, starchy wort — something we homebrewers generally strive to avoid as starch causes haze and may lead to biological instability in our beers. So why would anyone want to try this in their homebrewery? A few of the reasons include:

Authenticity: Traditionally the lambic family, wit-styled beers and low-gravity ales from Belgium were brewed utilizing a turbid mash.

High Adjunct Proportions: Some lambic and wit beer recipes call for unmalted wheat in high proportion in the mash, and in some cases oats or rye. Ungelatinized raw wheat needs special treatment such as boiling or a glucan rest to be sure the lautering process proceeds smoothly. Turbid mashing should sufficiently breakdown the sticky glucans and large proteins found in the unmalted wheat, but leave the protein haze characteristic of wit beers.

Starch for Souring: If you are ready to delve into the world of lambic-style brews, or brew any kind of experimental sour beer, one key to getting a lot of sour character is to be sure there is still some unconverted starch left in the final wort. The starch will provide fodder for the microorganisms in a sour beer to work on after the brewer’s yeast consumes all the simple sugars, such as maltose. Turbid mashing should leave a good concentration of unconverted starch in the wort.

Equipment

The basic turbid mash can be performed with one large (10 gallon/38 L) hot liquor tank (HLT), a smaller (~2 gallon/7.6 L) pot, a dedicated mash tun, a stuykmanden (read on) and a good mash paddle. You will also need another vessel, preferably the kettle, to hold the liquid first drained from the mash tun after the saccharification step has finished in the main mash.

A stuykmanden is a big basket used in Belgian brewing that is typically made out of wicker or copper that is lowered onto the surface of the mash through the top of the mash tank, where it acts as a strainer, allowing the liquid portion of the mash to filter through. At home you can use a colander. By pushing the colander down onto the top of the grain bed, free liquid from the mash will seep into the center bowl, which then can be siphoned out. Try to find a small, but deep colander which will fit in the top of your mash tun.

In The Brewhouse

The overall procedure of turbid mashing is fairly complicated, even compared to a decoction mash, so familiarize yourself with the schedule before jumping in. The first time you try this, focus on hitting the temperature marks first, and volumes and mash thicknesses second. The temperatures follow the basic steps found in many step infusion or decoction mashes, so feel free to substitute your favorite series of rests for those suggested here. Because most homebrew mash tuns have more than enough volume to hold the grains for a 5-gallon (19-L) batch, you will have plenty of space to thin the mash if the thickness becomes unmanageable. Take good notes and you will learn from your first turbid mash and be able to perform subsequent mashes more easily.

Dough in to 113 °F (45 °C). Your liquor to grist ratio at this point will be around 0.3 qt./lb. (~0.7 L/kg). Bring the water in the hot liquor tank (HLT) to a boil and, after the mash has rested 10 minutes, raise the temperature to 138 °F (59 °C) by stirring in boiling water. This should bring the mash to an overall thickness around 0.45 qt./lb. (~1 L/kg). Hold for 5 minutes at this rest.

Draw off about 1 qt. (1 L) of turbid wort (if brewing a 5-gallon/19-L batch of beer). Do this by sinking your colander into the mash and scooping or siphoning off the wort. An auto-siphon comes in handy for this. Do not collect any grain solids in this volume. (Skim them out with a strainer, if your colander lets some solid bits through.) Place the turbid wort in your small pot and heat it. An easy way to do this is to float the small pot in the boiling water in your hot liquor tank. You want the turbid portion to reach at least 180 °F (82 °C).

Now, stir in more boiling water to raise the temperature to 150 °F (66 °C). Hold at this temperature for 30 minutes, stirring often. The mash will still be thick, so you’ll have to work fairly hard at this.

Next, it’s time to use the colander again. This time, the mash is a bit thinner and you will collect about a gallon (3.8 L) of wort (again assuming you are brewing 5-gallons/19-L). Combine the wort you draw off with the first turbid wort in the small pot. Heat this portion in the small pot as before, aiming to raise it to at least 180 °F (82 °C). For the final mash rest, stir in boiling water to the mash tun and raise the temperature to 162 °F (72 °C) and rest for 20 minutes. While waiting to lauter, add water or otherwise cool the water in the HLT to 190 °F (88 °C).

Collecting the wort involves some unusual steps. First drain off some of the wort to the kettle — roughly the same volume that you have contained in your small pot. Replace the wort you ran off with the wort in the small pot. This should bring the mash temperature to 167 °F (75 °C). Hold for 20 minutes, then vorlauf and run off the rest of the wort, sparging with 190 °F (88 °C) water from the hot liquor tank.

From my experience with utilizing a turbid mash there are a few pointers to keep in mind to assure success when following the procedure laid out:

  1. Before starting, make sure your stuykmanden (colander) fits in the mash tun.
  2. Make sure that, by pressing down with the colander, you won’t be bending any temperature probes or crushing any screens or manifolds.
  3. Adding 0.5–1 lb. (0.23–0.45 kg) of rice hulls to the mash during the saccharification rest is a smart choice when using unmalted wheat. This is an added buffer to avoid a stuck sparge.
Issue: Special Issue: Guide to All-Grain Brewing