Wort Production (with malted grains)

Making wort from malted grains gives the brewer the freedom to control the attributes of his or her wort, most notably, its fermentability. You have many options on an all-grain brew day. Some of the options depend on how your brewery is configured, while others allow you to make decisions that impact beer quality.

In this article, we’ll discuss making wort from malted grains. In homebrewing terms, this would be described as making wort using all-grain methods. As with extract wort production, there are essentially three phases: Making the sweet wort, making the hopped wort and cooling this wort in preparation for fermentation. Unlike extract brewing, the production of sweet wort is more involved and more time-consuming. Essentially, the process includes soaking the crushed, malted grains in hot water. This is called mashing. Then the liquid wort is separated from the grain solids, and usually the grains are rinsed (sparged) to ensure a reasonable yield of sugars. This is called lautering. There are a number of variables that the brewer can manipulate that influence the quality of wort and quantity of extract achieved. To best understand the process, it pays to review the relevant characteristics of malted grain.

Malted Grains

The most widely utilized grain in brewing is barley, followed by wheat. Although small amounts of unmalted grains are occasionally used in brewing, almost all brewing grains are malted. Malting is a process that readies the interior of the grains for the mash and develops flavors in the husk. Basically, the seed grains are soaked in water until they sprout, then dried to stop any further growth. Then they are kilned (heated in an oven) to develop the bready, toasty flavors of malt — and, in the case of specialty malts, the more darkly roasted flavors of crystal malts and darkly-roasted malts, such as chocolate and black malt. Unmalted (seed) grain is very hard; malted grain is soft enough that it can be chewed. And, since malt can be chewed, you can taste it on brew day to ensure that it is fresh and lacking any of the flavors associated with staleness.

From the brewer’s perspective, malted grains contain a starchy interior and a flavorful outer husk. The goal in making wort is to convert as much of the starch into sugar as possible and extract the best flavor compounds from the husks without extracting tannins (husk components that lead to astringency in beer).

The Crush

How finely you crush your malt affects your brewhouse efficiency and the ease with which you can lauter your grain bed. The more finely you crush, the higher your extract efficiency. However, it becomes difficult to collect wort the more finely your malt is crushed. In addition, excessively finely crushed malt can yield more tannins when mashed and thus give your beer some astringency. Commercial breweries seek to have each husk broken into only two or three pieces and have the starch granules divided into large pieces, small pieces and powder, with large and small pieces each constituting over one third of the total.

If you crush your malt, experiment to find the right balance. Both your mill gap and the speed at which you crush affect your crush. Faster spinning rollers yield more finely crushed malt. The rollers on hand cranked malt mills move slower than is optimum. However, when the mill is powered by an electric drill, the rollers spin much faster than is optimum. To get your rollers moving at an optimal speed, you will need to motorize your mill. (There is an article on that in The Library, page 53.) Hand cranking and powering the mill with a drill both work, but you will need to experiment with adjusting your mill gap to get the best crush.

If you are unsure about your crush, for example if you are just trying out all-grain brewing, it is better to err on the side of undercrushed malt. If you crush your malt and all the kernels are broken open, that is enough. This will make lautering as easy as it can be (although you won’t get stellar extract efficiency).

Mash Temperature

Mashing has always been an extension of malting. In malting, the rock hard barley seed is transformed into the relatively soft malted barley kernel. Along the way, the seed is modified in many other ways. In the mash, these modifications may continue if the conditions are right. Long ago, brewers needed to begin mashing at lower temperatures — to take care of things like gum degradation or protein modification — before raising the mash temperature to the saccharification range (148–162 °F/64–72 °C) to convert the starch to sugars.

These days, most malts are made so that all a brewer needs to do is employ a single-infusion mash — a mash with only one temperature rest. Modern malts are sometimes called well-modified malts, to indicate that almost all of the ╥modifications╙ that need to be accomplished have been achieved during the malting process. Undermodified malts, usually Pilsner malts, can be found with a little looking and can be used if you want to do a multi-step decoction mash or other multi-step mash. In this article, I’ll focus mostly on single-infusion mashes. See The Library (p. 53) for information on other types of mashing.

In a single-infusion mash, the mash temperature is the primary way for a brewer to control the fermentability of the wort. If malts are mashed at the low end of the saccharification range (148–152 °F/64–67 °C), the resulting wort will be highly fermentable. The resulting beer will be dry compared to beers made from higher-temperature mashes. If you want to make an exceedingly dry beer (from wort with a very high degree of fermentability), you can add a rest —╤ up to a couple hours — at 140–145 °F/60–63 °C before raising the temperature into the regular saccharification range. Alternatively, you can extend the mash time to 90 minutes if you are doing a single-infusion mash. Stir the mash as frequently as is feasible. You can also substitute some highly fermentable ingredients (sugar, honey) for part of the grain bill.

If malts are mashed at the high end of the saccharification range (156–162 °F/69–72 °C), the resulting wort will show a low degree of fermentability. The resulting beer will finish at a higher specific gravity and be more filling. If you wish to make a wort with a very low degree of fermentability, employ a short (~20–30 minute) rest at the very top of the saccharification range (160–162 °F/71–72 °C), followed immediately by a mash out to 170 °F (77 °C). Additionally, you can add some relatively unfermentable carbohydrates, such as lactose, to the recipe.

For most beers, you will be striving for an intermediate level of fermentability. The key to achieving this is to pick an appropriate temperature (152–156 °F/67–69 °C) and mash long enough to get a negative result on a starch iodine test. Stir the mash and let the rest go to 30–45 minutes, if it hasn’t gone on that long (to improve your efficiency a bit), then mash out.

Mash Thickness

The thickness of your mash also affects the fermentabilty of your wort. However, this effect is much less pronounced than that caused by the mash temperature. If a mash is exceedingly thick, the starch granules will not quickly or completely dissolve and the enzymes will not be able to diffuse through the liquid and reduce the starch to sugar. Likewise, in an excessively thin mash, the starch would dissolve, but the distances between starch molecules and enzymes would mean the mash would be slow to convert. In practice, there is a fairly wide window of mash thicknesses in between these extremes that work well. Anything in the 1.0–3.0 qts./lb. (2.1–6.3 L/kg) range will work.

Homebrewers, especially those with limited space in their mash tuns, tend to favor fairly-thick, English╙ mashes around 1.25 qt./lb. (2.6 L/kg).

Brewers who make German-style lagers frequently favor thinner mashes, around 1.5–2 qt./lb. (3.1–4.2 L/kg) for dark beers and up to 2.5 qt./lb. (5.2 L/kg) for pale beers. If you are performing a step mash, thinner mashes are easier to stir when the mash is being heated.

Water Chemistry and pH

When you dough in (stir the grains and brewing liquor together), the pH of the mash should settle into the 5.2 to 5.6 range (with the lower half of that range being preferable). Many times, this will happen without any intervention by the brewer if he is brewing a type of beer suitable for his water. The theory behind water chemistry and brewing is beyond the scope of this article, but a few points should be made. (For a more complete description of water chemistry and how it effects your brewing, see The Library, p. 53.)

When measuring mash pH, be aware that pH is temperature dependent. If you heat any solution, its pH will drop. As such, if you take a sample from your mash and cool it to room temperature before taking a pH measurement, you will need to subtract 0.35 from your reading to account for the rise in pH that accompanied the cooling of the sample. Cooling your sample is necessary for some pH meters and also helps prolong the life of the probe on many other models.

Arguably, the most important part of water treatment for brewers using municipal tap water is getting rid of the chlorine or chloramines used in water treatment. There are two possible ways to do this. One is to use a relatively large activated carbon filter. The filters that are housed under sinks should do the job while smaller filters (for example, the types that attach to a faucet) may not. The other is to add potassium metabisulfite, available at home winemaking shops in the form of Campden tablets. One Campden tablet stirred into 20 gallons (76 L) will almost instantly neutralize any chlorine or chloramines. Because Campden tablets release sulfur dioxide (SO2), you should let the water stand, loosely covered, for 24 hours to let the rotten egg smell dissipate. (At 1 tablet per 20 gallons/76 L, it’s faint.)

Mashing In

There are at least three ways of mashing in, adding brewing liquor (water) to the crushed grains, adding grains to the brewing liquor or adding them simultaneously. Of the three, adding your grains to your mash tun, then stirring in water, is the worst option. Stirring water into dry grains frequently leaves little “malt balls,” pockets of dried malt that can be difficult to break up.

However, one small advantage to this method is you do not need to measure your brewing liquor, just keep stirring in water until you hit the correct mash thickness. This also allows you to take the mash temperature when the mash is almost mashed in, but still very thick and — if needed — make small temperature adjustments to your brewing liquor in order to hit your target mash temperature.

If you fill your mash tun with hot brewing liquor, then stir in the grains, you will likely have no problems with malt balls.╙ Plus, it’s a lot easier to stir your mash when performed this way. However, you need to measure the volume of your brewing liquor before you mash in and you do not have an opportunity to manipulate your mash temperature until you are completely mashed in. If you take good notes and are confident that by knowing your brewing liquor temperature and volume, you can hit your target mash temperature, stirring the grains into your brewing liquor is the quickest way to mash in.

A final option is to add the brewing liquor and crushed grains at (roughly) the same time. To do this, take two scoops of each volume. (I use beer pitchers.) If you add three scoops of brewing liquor to your mash tun, followed by two scoops of crushed malt, you can stir the mixture quickly and repeat. If you do this, you will add the malt and brewing liquor nearly simultaneously at a mash thickness around 1.5 qts./lb. (3.1 L/kg). You do not need to stir the grains and brewing liquor together completely for each addition as you will be stirring constantly as you proceed.

Additionally, you can always stir a few extra times when you are completely mashed in. When you are mashed in, your mash will be well-stirred with little temperature variation within the grain bed. This method also allows you to make temperature adjustments as you mash in. When you reach about 3⁄4 of the grains mashed in, take the temperature of the grain bed. It should be very close to your target mash temperature. If it isn’t, adjust the temperature of your brewing liquor to hit your target mash temperature.


In most commercial breweries, the mash is stirred continuously. This evens out temperature variation throughout the mixture and increases brewhouse efficiency. On a homebrew scale, stirring will do both of these things, but frequently this comes at the price of losing heat to the environment. If you have a heatable mash tun, stirring the mash a few times (say every 10 minutes) and re-establishing the temperature by applying heat will likely increase your extract efficiency. If you are mashing in a cooler, at the high end of the saccharification range (with the aim of getting a less fermentable wort), stirring is not advised due to the inevitable heat loss.

Mash Out

After the mash, you have the option of performing a mash out — raising the temperature of the mash to 170 °F (77 °C) to make the grain bed easier to lauter and to greatly slow the action of the enzymes. If you are making wort with moderate to low fermentability, a mash out is highly recommended. If you can’t heat your mash tun and don’t have the room to stir in boiling water for a mash out, you can begin sparging with very hot water 190–212 °F (88–100 °C) until the grain bed temperature reaches 170 °F (77 °C). At this point, cool the sparge water to hold the grain bed temperature at 170 °F (77 °C).

Collecting Wort and Sparging

Homebrew setups vary wildly and sometimes decisions about brewing techniques end up being made due to equipment limitations. One design-induced decision seen in homebreweries is a failure to heat the wort as it is being collected. This happens when the mash/lauter tun is placed about waist high (often on a counter) and the kettle is below it, on the floor. Heating the wort as you collect it shortens the brew day, as — if you use continuous sparging and time things right — the wort can come to a boil immediately after you are done collecting it.

Heating the wort also keeps the enzymes from continuing to work on the available carbohydrates, especially if you did not perform a mash out. Continued enzyme action at this point is something you want to avoid unless you are brewing a maximally dry beer. An easy solution to this is to run your wort into a small vessel (a grant, in brewing terms) and empty this into your kettle frequently. On my old homebrew setup, I used two beer pitchers for this purpose. When one was full of wort, I moved the outlet tube from the mash/lauter tun to the empty pitcher and poured the wort from the full pitcher into my kettle. I adjusted the ball valve on my mash/lauter tun so each pitcher would fill in about 5 minutes; this helped me time the runoff and keep the wort flowing at a constant rate. However, it also made for a very busy brew day.

Whenever sparging is described, using sparge water at 168–170 °F (76–77 °C) is almost always recommended. The idea is that tannins are extracted from the malt at an unacceptably high rate over this temperature. There are two problems with this idea. First, the temperature of your sparge water is not what is important — it’s the temperature of your grain bed. Given the small size of homebreweries, mash/lauter tuns can shed a lot of heat while you are collecting your wort. So, heat your sparge water to the point that your grain bed remains at 168–170 °F (76–77 °C) throughout wort collection, especially near the end. Second, tannin extraction is pH dependent. During most of wort collection, your pH will be low enough that excessive tannin extraction will not occur, even at temperatures near boiling.

Some homebrewers advocate lowering the pH of your sparge water by adding acid, based on the relationship between pH and tannin extraction. Adding acid to your sparge water may be appropriate, however, the pH of your sparge water is irrelevant — the pH of your grain bed near the end of wort collection is what really matters. Your mash is relatively acidic and heavily buffered, mostly because of the amino acids in solution, while your sparge water is not. No matter what the pH of your sparge water is, it will become the pH of the wort in your grain bed once it is mixed in. (The Library has an article on buffers, if you are interested.) If you’re worried about your pH while sparging, the reading you need to take is the pH of your final runnings. If this climbs above 5.8, stop collecting wort. You need to be vigilant to do this, the pH of the wort you collect will remain relatively constant for awhile (while it is still in the range of the buffers); then suddenly start to rise. If your water is rich in carbonates, you may need to add acid to your sparge water. However, the pH of the sparge water is not what’s important — it’s adding enough acid so that you can collect all your wort at under pH 5.8. And, you’ll have to find that amount out by trial and error with your water.

Continuous sparging is the most common method of sparging in commercial breweries, although in homebrewing batch sparging may now be more popular. Some homebrewers have given up continuous sparging due to difficulties in getting the flow rate onto the top of the grain bed to equal the flow rate out of the mash/lauter vessel. Others may never have tried because of the perceived complexity, or not wanting to buy the extra equipment (a ╥sparge arm). Continuous sparging, however, can be made very simple if you practice what I call “pulsed sparging.” (This may be a needless proliferation of terms, but I think it has some merit at the homebrew scale.) In pulsed sparging, you don’t worry about exactly matching the flow rates into and out of the grain bed. Instead, you periodically flood the top of the grain bed with water. At a homebrew scale, this may mean quickly adding a gallon (~ 4 L) or more of hot sparge water on top of the grain bed so that there is a few inches (~8 cm) or more of water above the grain solids. Then, let the liquid level drop so the grain bed is almost exposed and repeat the addition of water. You can use a sparge arm or just pour the water (gently) on top of the grain bed.

How Much Wort to Collect

For any given weight of grain in your grist, there is an optimal volume of wort to collect from the standpoint of extract efficiency and wort quality. At this point, you have sparged the grain bed sufficiently to get a good extract efficiency, but not so extensively that you have extracted excess tannins. The exact grain weight to wort yield ratio depends on a few factors (including your crush and water chemistry), but expect to get a minimum of 6 gallons of wort from every 10 lbs. of grain. This works out to 0.6 gallons per pound (5.1 L per kg). If you are using continuous sparging, begin checking your final runnings when you have collected this amount of wort. Stop wort collection when the specific gravity dips below 1.008 or if the pH rises to above 5.8.

In practice, many all-grain brewers simply collect enough wort to yield their target volume after the boil. For example, a brewer may always — regardless of how much grain a recipe calls for — collect 6.5 gallons of wort and reduce it to 5 gallons (19 L) after a 90-minute boil. This actually works well for ╥average-strength╙ (1.040– 1.057 SG/10–14 °Plato) beers. However, for progressively higher-gravity beers, this means more and more sugars are left behind in the grain bed and extract efficiency will get progressively worse. If you are interested in always getting the most from your grain bed, you will need to collect all the wort you can get from your grain bed, then boil this wort to reduce the volume.

Of course, an all-grain homebrewer may be interested in brewing a high-gravity beer, but not conducting a long boil. In this case, collecting only the high-gravity first runnings and boiling for a (relatively) short time is the solution. Shorter boils not only save time but reduce the amount of color pickup in the boil. The only cost is the price of the extra malt.

On the other side of the coin, when brewing a low-gravity beer, you may end up collecting too much wort if you collect your full pre-boil volume. In this case, you should collect all the wort you can, and then add water to make your full pre-boil volume. For example, let’s say you usually get 75% extract efficiency and plan to brew 5 gallons (19 L) of dry stout with an OG of 1.038. A reasonable grain bill for this would weigh about 7.5 lbs. (3.4 kg). If you used the ratio above as a guideline, you would collect 4.5 gallons of wort and then begin checking the OG or pH (or both). Once you stop collecting, you would need to add water to yield enough volume to perform a 60–90 minute boil.

The Boil

During the boil, the wort is sanitized, the hot break is formed, dimethyl sulfide (DMS) is volatilized and the alpha acids in hops are isomerized. A lot goes on, but — if you’ve already decided on the total boil time and the timing of the hop additions — there is relatively little for a brewer to do. If your boil is less than rolling, a little stirring every 5 minutes or so might be helpful. Likewise, when the first bits of foam form at the beginning of the boil, removing the chunks of coagulated protein from it with a strainer can help improve the clarity and flavor of your beer.

One thing you could do is monitor the pH of your boil. Your pre-boil wort is going to have a pH slightly higher than your mash pH (because the last, higher-pH runnings will raise the pH slightly). However, after the boil, you want your wort to be in the pH 4.2 to 4.4 range. Many times, this will happen naturally. If your boil pH is fine, a visual confirmation is that your hot break will be in the form of big, fluffy flakes.

However, some times you need to adjust the pH. There are two ways to do this. If you have only a half hour left in the boil and the pH has not dropped below 4.5, you can add acid (such as phosphoric acid) until the pH is in the proper range. An easier way to do this is to add a small amount of calcium to the boil. Around 25 ppm calcium ions, from gypsum or calcium chloride is all you need. If you add calcium and suddenly see the hot break turn big and fluffy, you’ll know that you have solved the problem.

How hops are added in the boil is another aspect of brewing where opinions diverge. Brewers that use pellet hops sometimes add them directly to the boiling wort while others place them in a bag, so they can be removed at the end of the boil. If you bag your pellet hops, you need to leave plenty of room for them to expand. Don’t fill more than one third of the bag with pellets. Even filled loosely, however, adding the hops in a bag may limit your hop utilization. On the other hand, if you simply add the hops to your kettle, you will have to find a way to deal with the hop debris when the wort is cooled and being transferred to the fermenter. As such, you may need to leave behind some wort to avoid transferring too much “gunk” to your fermenter. (If you have a hop back, you can avoid this problem by letting it filter out the hop debris and trub.) Longer settling times allow the hop debris and trub to compact more at the bottom of the kettle, and whirlpooling the wort will ensure that the material is deposited in a cone near the center of the kettle.

If you add pellet hops directly to your wort, they have a tendency to cling to the side of the brew kettle, just above the wort line, after they dissolve. Be sure to knock these back down into the wort as the boil proceeds. They aren’t contributing anything to your wort while they are clinging to the side of the pot.

Brewers using whole hops need a way to strain them out at the end of the boil. Some spigotted brewpots have a built-in strainer designed to screen out pellet hops, and these are also sold as add ons. If you bag the hops, they won’t expand as pellet hops do, but you still need to give them room for wort to flow past them. Don’t fill the bag more than half full.

You can make quality beer with either pellet hops or whole hops. On brew day, your main concern is how to deal with them after the boil.

Wort Chilling

After the boil, you need to chill the wort to the point that you can pitch the yeast into it without stunning or killing them.

Homebrewers typically use an immersion chiller or either a counterflow wort chiller or plate chiller. Any of these will chill your wort, but the different methods affect your beer.

An immersion chiller chills your wort in bulk. As you chill, the wort eventually falls through a temperature range (from 160–120 °F/71–49 °C) in which wort contaminants are no longer killed by the heat and can in fact grow quickly in the warm environment. You should cover your kettle when the wort is passing through this temperature range to minimize the amount of airborne contamination.

If you are using a counterflow or plate chiller, the surface of your wort in your kettle is always going to be near boiling, so you don’t need to cover it as you chill. This type of chiller also forces you to decide what to do with the cold break, as it is not left behind in the kettle as with an immersion chiller. After the cold

break settles, it is best to separate

the wort from it. If you have a conical fermenter, this is as easy as opening the valve at the bottom of the cone for a moment.

Finally, using a counterflow or plate chiller allows the late addition hops, and especially the hops added at knockout, more contact time with near boiling hot wort. Switching between chiller types on different brew days can alter the late hop flavor and aroma of a beer brewed with the same recipe.

Conditioned Milling

In homebrewing, malt is almost always crushed dry, using a two-roller mill. In larger commercial breweries, four or six roller mills may be employed and sometimes the malt is wetted before crushing.

In conditioned dry milling, malt is exposed to steam or sprayed with 86–95 °F (30–35 °C) water for 1–2 minutes prior to milling. Due to this treatment, the moisture content of the husks rises by couple percentage points.

In steep conditioning, the malt is sprayed with water at 140–158 °F (60–70 °C) for 50–60 seconds prior to milling. The hotter water results in faster water uptake by the husks, which reach up to 22% water by the end of the steep. (The moisture content of the interior of grain should not rise more than 1%.) For every 10 kg of malt, about 6 L of water is used. As much as half of this water, however, is not absorbed by the grain.

If you are an advanced all-grain brewer that has had problems with small husk particles, astringency or slow runoff when using finely-crushed malt, you may want to experiment with conditioning your malt. There are a couple ways you can approach this.

Conditioning with Steam

To wet your malt with steam, you’ll need a large steeping bag and a heatable lauter tun with a false bottom. Add water to your lauter tun until it is just below the level of the false bottom and bring it to a strong boil. Place your (uncrushed) malt in the steeping bag and lower the bag into the lauter tun. During the next 2 minutes, steam from the boiling water will be forced up through the grains. Open the bag, take your mash paddle and stir the malt gently while it is being steamed. Put a lid on the vessel when you are not stirring. After the steaming period, lift the bag out and stir the malt for about a minute, then begin milling. The boiling water in the lauter tun can be returned to your hot liquor tank.

Conditioning with Hot Water

To wet your malt with hot water, you will need essentially the same set-up as with steam conditioning, but your lauter tun does not need to be heatable. You will also need a way to spray or sprinkle the water over the grain. A watering can, as used by gardeners, or a sparge arm will work fine. In this case, instead of boiling water below the malt, you will be sprinkling hot water over the top of it. Measure out roughly 6 L of water for every 10 kg of malt — about 3.5 gallons per 10 lbs. — you are conditioning. Heat your water to 158 °F (70 °C) and sprinkle it over the malt for 50 seconds, aiming to pour out the entire volume evenly during that span. Let the excess water drain into the space Let the malt sit for a minute or two, then crush it.

Issue: March-April 2013