Lautering 101


If you’re an extract brewer thinking about going all-grain, one of the most important steps to understand, after mashing, is lautering. Lautering is the process by which the brewer separates the liquid sweet wort that will go on to the boil from the solid spent grain once the mash is complete. And while many brewers think of lautering as simply rinsing the grains, there is a bit more to it. A successful lauter is important for brewing your best all-grain homebrews, and if you take your time and do it properly, you can avoid problems like astringent flavors, and also maintain consistency from batch to batch.

There are a number of different methods by which lautering can be achieved, but equipment-wise the grains are separated from the wort using a vessel with a sieve or holes in the bottom. The most common setup in homebreweries is a mash-lauter tun. A home mash-lauter tun is most often constructed out of a picnic cooler or a kettle fitted with a false bottom, pipe manifold, braided hose, or some other type of filter to separate the spent grain from the wort. These types of tuns can be purchased pre-built from homebrew supply stores or can be built at home using materials easily found at your local hardware store. Lots of homebrewers have also started brewing all-grain using Brew-In-A-Bag (BIAB) which uses a fabric filter in the brewpot. See the sidebar on page 48 for more on BIAB.

The Steps

Lautering is typically done in three steps: mashout (often considered optional), recirculation, and sparging. Mashout is performed by raising the temperature of the mash to 170 °F (77 °C) after the enzymatic conversion of starches to sugars is complete, but before the spent grain is separated from the sweet wort. Mashout begins to denature the enzymes present in the mash, thereby halting any additional enzymatic conversion and effectively “locking in” the wort sugar profile attained during the mash. In addition, raising the temperature of the sweet wort decreases its viscosity, making it easier for the sugary liquid to flow through the grain bed and out of the mash-lauter tun. If the mash is being performed in a kettle mash-lauter tun then mashout temperature can be achieved by directly heating the tun and either stirring the mash, or recirculating the wort until mashout temperature is reached. If the mash is being performed in a cooler mash-lauter tun then hot water can be added to the mash in order to bring the temperature up to mashout levels.

As mentioned earlier, the mashout is often not necessary, as the wort will be fluid enough to flow through the grain bed and out of the mash-lauter tun without much of an issue. Also, most homebrewers will drain the mash-lauter tun directly into their boiling kettle where heat can readily be applied, thereby stopping enzymatic activity. However, a mashout can be helpful in some instances; for example, if a thick mash ratio (less than 1.5 quarts (1.4 L) of water for every 1 pound (0.45 kg) of grain) is used or if a high percentage (greater than 25%) of sticky or gummy grains are being mashed, such as wheat, rye, oats, or unmalted barley.

Once the mash is complete (and optionally the mashout), it’s time to begin draining the sweet wort from the mash-lauter tun. The next step, then, in the process of lautering is recirculation, which is done to clear the wort of large bits of protein and grain. When the valve is opened and the wort begins to drain, the first few quarts of liquid will be very cloudy and contain a lot of particulates (grain husks and coagulated protein) that are best removed before the wort flows into the kettle. In order to do this, collect the wort carefully with a small container (a quart/liter or so — a pitcher shape works well) and carefully pour the wort back over the top of the grain bed in the tun until it settles and forms a filter bed through which clear clean wort can flow. This process is very often called “vorlauf,” which is German for “temporary.” This typically only takes a short amount of time — about 15 minutes — and once the wort starts to flow clear it can then be drained into the boiling kettle, which leads us to the next step: Sparging.

Sparging is the process by which additional water that has been heated to 170 °F (77 °C) is used to rinse the residual sugars from the grain bed into the brew kettle. The two most common methods by which homebrewers achieve this are batch sparging and fly (or continuous) sparging. Batch sparging is arguably simpler and faster, and is probably more popular among homebrewers these days, especially among those with simple brewing setups, whereas fly sparging requires a bit more time and attention by the homebrewer. To batch sparge, the wort is recirculated until clear and completely drained from the mash-lauter tun into the brew kettle. Next, an addition of sparge water is added to the tun, the mash is stirred, allowed to rest for 3–5 minutes, recirculated once again, and then again drained into the brew kettle. This process is often repeated a second time.

When fly sparging, the wort is recirculated until clear and then slowly drained into the boiling kettle until the wort left in the tun is approximately 1 inch (2.5 cm) above the top of the grain bed. At this point, sparge water is slowly added to the top of the tun in order to maintain the liquid at that 1-inch (2.5-cm) level. This process continues until the majority of the sugars have been rinsed from the grain, typically about 60-90 minutes.

Either batch or fly sparging can be used successfully with various types of mash-lauter tun configurations; however, certain tun shapes work better with batch sparging, while others are more ideal for use with fly sparging, and this should be taken into some consideration when deciding which method is best for you. The fluid flow dynamics of mash-lauter tuns that are shorter and wider and have a single drainage point, such as a rectangular picnic cooler with a braided hose, are great for the faster batch sparging; whereas the fluid flow dynamics of tuns that are taller and narrower and have numerous drainage points, such as a round picnic cooler or kettle with a false bottom, works great for slower fly sparging. Both methods can be done in either shape of mash-lauter tun, however.

Whichever method you choose, mastering the nuances of lautering is an important step in becoming a great partial mash or all-grain homebrewer, and being able to produce consistent, great quality beers to share with your friends and family.

Batch Sparging

To batch sparge, the wort is recirculated until clear and completely drained from the mash-lauter tun into the boil kettle. Next, an addition of sparge water is added to the tun, the mash is stirred, allowed to rest for 3–5 minutes, recirculated once again, and then again drained into the boiling kettle.

Troubleshooting a Stuck Sparge

Lautering is generally a very straightforward, uneventful process, but occasionally the dreaded stuck runoff, which is often called a “stuck sparge” or a stuck grain bed, will show up and ruin your otherwise pleasant brew day. A stuck sparge occurs when the flow of sweet wort from the mash-lauter tun slows to a trickle or worse yet, completely stops. Luckily, there are a number of things the homebrewer can do to help prevent stuck sparges from ever occurring in the first place.

If you are using a homemade pipe manifold in your mash-lauter tun, then it is essential that it be designed properly – with enough drainage points and large enough holes (approximately 1⁄8-inch or 33-mm) to allow the sweet wort to flow through easily. Equally as important is milling your grain properly, as it is the husk of the grain that forms the actual filter bed in the tun. Ideally, the grain should be milled fine enough to crack the husk and release the fragments of starchy kernel from inside, but not so fine that the husk is ground into tiny pieces or powdered. A good roller mill is typically the best way to achieve the ideal crush for brewing beer, and many local homebrew supply stores will have a roller mill available for customers to use.

Even if these guidelines are followed, sometimes a stuck mash can still occur, often due to the ingredients used in certain styles of beer. Some beer recipes call for the addition of wheat, rye, oats, or unmalted/flaked barley into the mash. When used in large amounts, these ingredients can be very gummy due to their high beta-glucan content, and can lead to a stuck mash. If a recipe calls for greater than 25% of any of the above ingredients, there are steps the homebrewer can take to help avoid the frustration of a slow or stuck runoff.

One option that can be considered is the addition of rice hulls to the mash at a rate of 0.25–0.5 lb. (0.11–0.23 kg) for a typical 5-gallon (19-L) batch of beer. Rice hulls act as a filter aid by preventing gummy grain from forming clumps and impeding the flow of wort though the grain bed. Rice hulls are most effective when added to the milled grain before the mash is started, but they can also be stirring into the mash after it is complete if you’ve found yourself with an unexpected slow or stuck runoff. Another option that can be very helpful is a beta-glucanase rest, during which the temperature of the mash is raised, either by direct heat or the addition of hot water, to 98–113 °F (37– 45 °C) and rested for 20 minutes. This step will break down some of the gummy beta-glucans in the mash, allowing it to flow more easily.

The next step that can be taken is to perform a mashout by raising the temperature of the mash to 170 °F (77 °C), again either by direct heat or the addition of hot water, to decrease the viscosity of the sugary wort, allowing it to flow more easily. Once the mashout is complete and it is time to sparge, making sure that your sparge water is heated to 170 °F (77 °C) will ensure that the temperature of the grain bed is maintained during the runoff. Also, if you’re utilizing a fly sparge, it is important to maintain approximately 1 inch (2.5 cm) of liquid above the top of the grain bed at all times, as allowing the grain bed to run dry will cause it to compact, making it more difficult for the sparge water to flow through.

Lastly, if all else fails, as a last resort the mash can be scooped or poured (very carefully!) out of the mash-lauter tun and into a separate vessel lined by a large filter bag, which can then be raised out of the vessel, allowing the wort to drain out. Most importantly, once your brew day is complete you should try to figure out why your mash stuck in the first place, and what you can do to prevent it from happening again in the future.

Lautering and Brew-In-A-Bag (BIAB)

An increasingly popular alternative way to all-grain brew is the “Brew-In-A-Bag” (BIAB) method, which utilizes a kettle lined with a large fine mesh filter bag rather than the more traditional mash-lauter tun.

Briefly, to brew-in-a-bag, the milled grain is placed into a large, fine mesh strainer bag that is then lowered into a kettle containing the entire pre-calculated volume of water (heated to strike temperature) necessary for the batch and stirred. The mash is then conducted, followed optionally by a mashout. Then, to lauter, the bag is simply lifted out of the kettle and allowed to drain — and even sometimes squeezed — at which point the brewer proceeds with the boil as usual.

BIAB is a very straightforward but effective method that allows homebrewers to venture into partial mash or all-grain brewing with little investment in additional equipment, other than a BIAB bag; reusable versons are typically made from a fine voile fabric or nylon mesh and sell for around $30.
This method also has the advantage of saving brewers time — a typical BIAB brew day can save as much as two hours as compared to a typical all-grain brew day (if using a continuous sparge).

Issue: October 2016