Brew a Scottish ale with an All-Grain, Single-Infusion Mash
Brewing beer from a full mash takes significantly more time than brewing an extract beer. Some of the extra time comes from added steps in the procedure, such as the mash, recirculation, run-off and sparge. (Don’t worry, I’ll explain these terms later.) Other blocks of time are needed to heat the larger volumes of water needed to brew an all-grain beer. You also have to clean the additional equipment used in brewing an all-grain beer.
Although it takes more time, there are many advantages to brewing “from scratch.” All-grain brewers can manipulate the conditions of the mash to make their wort exactly as they want it. They can, for example, adjust the fermentability of the wort, a topic we’ll discuss in more detail in Homebrew 501. Beer made from a more fermentable wort will be dry. In general, an all-grain brewer can make a wort that will ferment to a lower specific gravity than an extract brewer can. A less fermentable wort yields a beer that finishes sweeter. We’ll brew a sweet beer — a Scottish ale — in this article.
In the long run, brewing all-grain beers is more economical. When you buy malt extract, you are paying not only for the malted barley, but the expense of mashing the grains, separating the wort from the husks, and condensing the wort into extract. So, malted barley grains cost about half as much as an equivalent amount of malt extract. Of course, the start-up cost for brewing an all-grain beer can be substantial. At a minimum, you need a mash-lauter tun to hold the grains.
A homebrewer contemplating switching to all-grain brewing may be intimidated by the amount of information out there. Homebrewing books and online homebrewing forums are filled with talk of appropriate mash thicknesses, stepped temperature regimes, pH and mash efficiencies. These are all important theoretical considerations. However, in most cases a practical brewer can brew without worrying about all these variables. And keep in mind that, although there are many varieties of stepped-temperature mashes, many commercial brewers and homebrewers use a single-infusion mash for their beers. For your first all-grain beer, you should be fearless — just jump right in. Remember, you’re soaking grain in hot water, not performing brain surgery.
Scottish ales are big, malty brews. The yeasts used in brewing Scottish ales are not very attenuative, which means they drop out of solution earlier than other ale yeasts. Because of this, they leave more residual sugar in the finished beer. Scottish ales have little hop bitterness, and usually no hop flavor or aroma. Heating the Water
Although some of the later steps may be intimidating to a first-time all-grain brewer, an all-grain brew day starts with a simple task — heating water. When mashing, you need a large volume of hot water to mash the grains. About an hour later, you will need another large volume of water for rinsing the grains, or sparging. In all, you will need about 10 gallons of hot water to brew 5 gallons of beer.
If you begin heating all your water first, you can clean and set up your brewing equipment while it heats. Having a reserve gallon or two of cold or room-temperature water will come in handy on brewing day. Likewise, having a reserve gallon or two of boiling, or near boiling, water will also come in handy.
Heating all the water needed for an all-grain batch can literally take hours on a kitchen stove, especially an electric stove. Most all-grain brewers eventually switch to a propane cooker to heat their water and boil the wort. These cookers will greatly decrease the amount of time it takes to heat water and will give you the power to bring your full wort to a nice, rolling boil.
Mashing In
To begin the mash, or to mash in, you combine the 9 lb. 3 oz. of grains with about 3 gallons of 170° F water. To do this, place the crushed grains in your mashing vessel, the mash tun. With a large measuring cup or a beer pitcher, add hot water to the grains. Stir the mash each time you add water to break up clumps of grain. These clumps can form a ball that seals liquid away from their dry core. Having dried clumps in your mash will lower the amount of fermentables you extract from the grain. It may also add starch to your beer.
As you ladle water onto the grains, work quickly. As you are working, heat is escaping from your mash into the environment. You don’t need to rush, but work at a steady pace. Once there is enough water in the mash tun to barely cover the grains, take the mash temperature — it should be close to 158° F. If the temperature is higher than 158° F, stir in cool water from your reserve until the temperature sinks to 158° F. When you stir in this water, make sure to stir the mash enough that the temperature is even throughout the mash.
If the temperature is less than 158° F, stir in water from your boiling water reserve until the temperature rises to 158° F. Be sure to stir well. Once your mash temperature is right at 158° F, look at the water level in your mash tun. If there is about an inch of water (or more) above the top of the grains, put the cover on your mash tun. If there is less than an inch of water on top of the grains, add 170° F water until there is. This will raise the temperature, but not by much. You don’t need to stir this water in. The inch of water on top of the grains will be mostly absorbed during the mash as water continues soaking into the grain.
The mash
At this point, seal your mash tun. If you are mashing in a modified picnic cooler, shut the lid. If you are mashing in a brew-pot or modified brewpot, put on the cover and insulate with towels or a mash-jacket. Let this mash sit for an hour. If your mash tun is insulated well enough, the temperature should stay roughly constant. It may drop a few degrees, but that’s nothing to worry about. While the grains are mashing, heat 2 gallons of water to the boiling point.
A lot occurs in the mash. Hot water soaks into the center of the grains and dissolves the starch. Starch is a large molecule found in great abundance in the barley kernels. Starch molecules are chains of simpler sugars. The seed stores sugars that are needed to fuel early growth of the plant. The starch is cut up by enzymes, called amylases, present in the grain. The starch molecules are gradually reduced to smaller sugar molecules, mostly maltose.
Although a lot is going on in the mash, the brewer doesn’t need to do anything. If you’d like, you can stir the mash occasionally. You may increase the efficiency of mash by doing this, but you will also lose heat every time you open the mash tun. If you do open it, you will need to stir in boiling water to boost the temperature back up to 158° F. If you just let the mash sit for an hour, you can be cleaning brewing equipment used in later stages. In any case, you will need to heat the water used to rinse the grains — the sparge water — towards the end of the mash.
The mash-out
After an hour of mashing, open your mash tun and take the mash temperature. Note this in your brewing notebook. Then, raise the temperature of the mash to 168° F. To do this, stir in the boiling water a few cups at a time. Take the temperature each time. Once you reach 168° F, seal the mash tun again and wait for 15 minutes. Boosting the temperature to 168° F will make the sugary wort less viscous, and easier to drain from the grain bed. You can skip this step if you’d like. Due to limitations of their equipment, many brewpubs do. But, it can increase the amount of fermentables you extract from your grains and stop the enzymatic action in the mash.
Recirculating
With a full mash, you reverse these two steps. First, the wort is recirculated through the grain bed until it clears. During recirculation, the floaties get trapped in the top layers of the grain bed. After recirculation you proceed to the run-off and sparge, when clear wort is drained from the grain bed.
To begin recirculation, open the valve on your lauter tun. For most hombrewers, the lauter tun is the same vessel as the mash tun. In a few breweries, however, brewers mash in one vessel, then transfer the mash to a separate vessel for rinsing the grains, or lautering. Once you open the valve, cloudy wort should start flowing. Collect this wort in a large measuring cup or beer pitcher. Once the container is full, pour this wort on top of the grain bed. As you continue recirculating, you will notice the wort clearing. For a 5-gallon batch of beer, about 20 minutes of recirculating the wort is usually sufficient.
While recirculating, you want the wort to drain from the grain bed at a rate of about three quarts every five minutes. (Two quarts is 64 oz., about the volume a pitcher of beer holds. At 3 quarts per 5 minutes, a beer pitcher should fill in a little over 3 minutes.) At this rate, at the end of twenty minutes you will have recirculated the entire volume of wort in the grain bed. The wort should now be clear of large husk pieces and large grain particles. To control the rate that the wort drains, you will need to adjust the valve on your mash tun frequently.
The run-off
Once the recirculation period is over, continue draining the wort from the grain bed. However, this wort should go to the brew kettle. You can begin heating the wort as you collect it, but don’t bring it to a boil. During the run-off period, you should be draining wort at about 2 quarts per five minutes or slightly less. The run-off period will be relatively short; it ends when the liquid level in the lauter tun falls to the level of the grain bed. Once the grain bed is about to be exposed, it’s time for the sparging. The sparge During sparging, you continue running off clear wort as you did before. However, you add hot water to the top of the grain bed at the same rate as wort is being drained off. As a result, as you collect the remainder of your wort there will always be a little water on top of the grain bed.
There are a couple different ways to add sparge water. You can ladle a quart or two of water on top of the grain bed when the level gets low. Alternately, most homebrew stores sell sparge arms. Sparge arms are like little lawn sprinklers for your mash. Hot water drains from a container (often the homebrewer’s bottling bucket) through nylon or plastic tubing to the sprinkler. The rate of water can be adjusted either by opening or closing the valve on the bottling bucket or by partially clamping the nylon tubing leading to the sprinkler.
The sparge water should be heated to between 160° F and 170° F. The heat from the sparge water keeps the temperature of the grain bed up. At higher temperatures the thick, sugary wort will flow freely through the grain bed. As the grain cools, the flow of wort slows. At temperatures higher than 170° F, tannins could be leached out of the grains. So, avoid overheating your sparge water. If the water is significantly cooler than 170° F, it may slow down the drainage of your wort.
Remember to keep checking the rate at which the wort is draining. You should be collecting wort at a rate of about 2 quarts every 5 minutes. As you continue collecting wort, the valve may become progressively blocked with small particles from the mash. If the rate of wort drainage drops too low, or stops altogether, open the valve all the way for a few seconds until the flow resumes. Then slowly close the valve to the proper flow rate.
It can be difficult to get the wort to drain at a constant rate. You will probably need to fiddle with the valve quite a few times. As long as your rate is in the right ballpark, you’ll be fine. If you finish collecting your wort in less than 45 minutes, you’ve gone too fast. If it takes over an hour and a half, you’re going too slow. Once you’ve collected six gallons of wort, shut the valve off.
Boiling, cooling and fermenting
You will finish brewing this beer as you did the beer in Homebrew 301. You will boil and cool the entire wort. The cooled wort will be siphoned to your fermenter and aerated. However, you will notice a few differences when handling an all-grain wort.
We’ll start the boil with 6 gallons of wort, more than before. There are two reasons for this. First, with a propane cooker you can supply more heat to the wort. This added heat will increase the evaporation rate compared to the evaporation rate from boiling the wort on your stovetop. In our one hour boil, we will reduce our wort from 6 gallons to just over 5 gallons.
Second, we expect a larger hot break from an all-grain wort than from an extract wort. Very soon after the boil commences, you will see little light-colored flakes in your wort. This is the hot break. The hot break is little clumps of coagulated proteins and lipids. This material will settle to the bottom of the kettle while the beer is cooling. If all goes well, there will be five gallons of clear wort sitting atop a few quarts of break material. This clear wort will be siphoned to the fermenter, leaving behind as much of the break material as feasible. In an extract wort, the hot break was already left behind in the process of making an extract (although procedures for making extract vary). Therefore, we expect less break material from an extract wort.
—Chris Colby
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Many ways to mash your malt
Most homebrewers use one of two arrangements for mashing grains and draining the wort. One set-up involves modifying a picnic cooler to hold a framework of copper pipes on its bottom (see diagram above). The copper pipes are cut with slots that allow wort to flow through but are too narrow for the grain. The pipes channel wort outside the cooler. A valve allows the homebrewer to control the flow of wort out of the cooler when draining the wort. Picnic coolers are well insulated and can hold the mash at a steady temperature for the entire duration of the mash.
The second common type of mash tun is a large brew pot with a “false bottom” inserted. The false bottom sits an inch or so above the kettle’s floor and is perforated, so the grain stays behind but the wort can flow through. A valve below the false bottom is used to drain wort once the mash is complete. An advantage of this type of mash cooler is that it can be directly heated. The diagram below shows a picnic cooler mash tun with a false bottom, but a brewpot mash tun would look similar.
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Scottish Ale
OG = 1.055 FG = 1.020 IBU = 22
9 lbs. pale ale malt
2 oz. chocolate malt
1 oz. roasted barley
6.25 AAU of Fuggles hops (1.25 oz. of 5% alpha acid)
Wyeast 1728 (Scottish ale)
3/4 cup priming sugar
4 days before brew day
Make yeast starter
Refrigerate yeast starter
3 days before brew day
Aerate starter
Pitch yeast
On brewing day
Heat 10 gallons of water to 170° F
Mix 3 gallons of 170° F water with the crushed grains
Allow grains to mash for 1 hour
Boil 2 gallons of water (from the remaining 7 gallons at 170° F)
Raise temperature of mash to 168° F by adding boiling water
Allow grain bed to set for 15 minutes
Recirculate wort for 20 minutes
Prepare 4 gallons of sparge water at 170° F
Run-off and sparge wort at rate of 2 quarts every 5 minutes
Collect 6 gallons of wort
Bring wort to boil
Add bittering hops
Cool wort with wort chiller
Siphon cooled wort to fermenter
Aerate wort
Pitch yeast
Ferment for one week
1 week after brewing day
Rack to secondary fermenter
2 weeks after brewing day
Test beer with hydrometer
Prime and bottle when gravity is constant for 3 days
Condition for 1 week
Refrigerate for 1 week
3 weeks after brewing day
Beer is ready!
