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# The Extract Equation

These days, there is no shortage of beer recipes for a homebrewer to choose from. Entire books are devoted to beer recipes; magazines like BYO publish them every issue. And Web sites are home to hundreds of recipes submitted by homebrewers. Unfortunately for extract brewers, many of these recipes are all-grain and don’t include an extract version. Luckily, there is a straightforward way to convert almost any all-grain recipe to an extract recipe. And sometimes you can reverse the steps to convert an extract recipe to all-grain.

Converting a recipe is only part of what you need to do to brew a beer similar to the one in a recipe. In order to closely match the flavor of the original beer, you may need to modify some of your extract brewing procedures to match all-grain methods, such as performing a full wort boil. The closer your brewing procedures match those of the recipe’s author, the less you’ll have to alter the original recipe.

In this article, I’ll take you step-by-step through how to convert an all-grain recipe to an equivalent extract recipe. I’ll point out where all-grain brewing procedures will require alterations to either the extract recipe or to your extract brewing procedures. I’ll also discuss how to make your extract beer as similar as possible to the original all-grain beer.

##### Step One: Converting Volume

The first step in converting any recipe is to scale the volume of the all-grain batch to the size of your batch. To do this, simply divide the size of your extract batch by the volume of the all-grain batch. Then multiply the amount of each ingredient in the all-grain recipe by this number to obtain the amount you need in the extract recipe.

For example, if the all-grain recipe is for 15 gallons of beer and you plan to brew a 5-gallon batch, multiply the amount of each ingredient by (5/15 =) 1/3.

##### Converting Hops

All other things being equal, you should add exactly the same amount of hops to your extract recipe as are called for in the scaled all-grain recipe. Unfortunately, all other things are rarely equal. Even if you use the same variety of hops and boil the hops for the same length of time, you may need to compensate for two important variables: the alpha-acid ratings of the hops and the density of the wort during boiling.

##### Hops With Different Alpha Acids

Alpha-acid ratings measure the bitterness level of the hops. Different hop varieties have different alpha-acid levels. And different crops of the same variety may also vary in levels of bitterness. So five ounces of Hallertau hops from one source may provide a different level of bitterness than five ounces of Hallertau from a different source. To compensate for hops of different alpha-acid ratings, divide the alpha-acid rating of your hops by the alpha-acid rating given in the recipe. Multiply the amount of hops used in the recipe by this number. For example, if the recipe gives 3 ounces of Saaz hops at 3.5% alpha acid (AA) and the hops at your homebrew store are rated at 4% AA, you need to add ((3.5/4) x 3 =) 2.6 ounces of the 4% AA hops.

If you’re math-phobic, pick a similar style of hops with an alpha-acid rating as close as possible to the hops in the recipe.

##### Differences in Wort Density

One way that extract brewing typically differs from all-grain brewing is in the density of the wort as it is boiled. Some extract brewers boil a concentrated wort, then dilute the wort to working strength by adding water to the fermenter. All-grain brewers, however, have to boil their worts at or near working strength. For a 5-gallon batch, the extract brewer may boil 2 gallons of wort, then dilute it in the fermenter. The all-grain brewer may boil 5.5 to 6 gallons and end up, after losses to evaporation, with 5 gallons.

There are two important consequences of this difference in brewing procedure. First, the amount of bitterness extracted from the hops decreases in thicker worts. So the extract brewer boiling a concentrated wort will extract less bitterness from the same amount of hops. Secondly, the amount of caramelization that occurs during boiling increases with wort density. So an extract brewer will produce a darker beer when using an equivalent “grain bill” as an all-grain brewer. This will be especially noticeable if you try to brew a light-colored beer.

To compensate for the difference in hop bitterness extraction for worts of different densities, divide the hop extraction expected from the density of your wort by the hop extraction expected from the density of the wort in the all-grain recipe. You will have to calculate the density of your wort, then look up the expected extraction on a hop extraction chart at the start of the story. Use the original gravity of the all-grain recipe to look up the second number.

To estimate the density of wort, divide your batch size by the number of gallons of wort you will boil. Multiply this number by the number of gravity points expected. (Gravity points are the decimal portion of the beer’s expected original gravity.) For example, let’s say you are going to brew 5 gallons of pale ale with an original gravity of 1.048. You plan to boil 3 gallons of wort, then add water in the fermenter to make 5 gallons. Your wort density is ((5/3) x 48 =) 80. This means the specific gravity of your wort during the boil is 1.080.

So, to calculate how much hops you would need, divide the hop extraction for your thick wort by the hop extraction from the working strength all-grain wort. Then multiply this number by the amount of hops. From Table 1 we can see that for a wort of 1.080, hops boiled for 1 hour should yield 18.7% of their AA. Hops boiled for 1 hour in a wort of 1.048 should yield 22.5% of their AA. Thus, if the all-grain recipe called for 3 ounces of hops you would need ((22.5/18.7) x 3 = ) 3.6 ounces of hops.

To avoid having to do this calculation, boil your entire wort just as the all-grain brewer did.

##### Converting Spices

Like hops, spices vary in their potency. The heat of chili peppers, for example, is rated in Scoville units. Unlike hops, however, it’s unlikely that you’d see such a rating for spices in a homebrew recipe. (I’ve never seen one.) So, when adding spices or flavorings to a homebrew, the best you can do is add the same amount as specified in the scaled all-grain recipe. Also, be sure to use the freshest spices available and use whatever procedure was used in the original recipe (adding the spice to the secondary, for example, or making an extract with alcohol). After you finish your first batch of the beer, you can taste it and adjust the spices as desired.

##### Step Three: Converting Specialty Grains

Specialty grains add both fermentables and flavors to beer. When converting an all-grain beer to extract, it’s best to temporarily forget about the fermentables and focus on the flavors. When handled in a similar manner, one ounce of a specialty grain in an extract beer should impart the same amount of flavor as an ounce of the same specialty grain in an all-grain beer.

There are two broad classes of specialty grains, stewed and roasted. After malting, stewed grains are heated in a closed environment so that moisture cannot escape. The end result is the starch in each kernel is partially to mostly converted to sugar inside the husk. Roasted grains are heated with hot air after mashing and are dried in the process. Most of the starch is not converted to sugar. A third type of grain is roasted barley; roasted barley is unlike stewed or other roasted grains in that roasted barley is not mashed prior to roasting.

When brewing an extract beer, stewed grains can be steeped in hot water or mashed. Most roasted grains, especially those with a high starch content, should be mashed so that they do not contribute starch to the wort. For simplicity’s sake, it is best to make a partial mash with all your specialty grains, even those that could be steeped. A partial mash is only slightly more involved than steeping. And, the flavors you get from the specialty grains in the partial mash will more accurately reflect the original recipe.

To prepare for your partial mash, measure out the same amount of each specialty grain as called for in the (scaled) all-grain recipe. Add the specialty grains to a nylon mesh bag. Add an amount of pale malt equal to the amount of specialty malt to the nylon bag. (Record the amount of pale malt used in this step. You will need to account for it later.) All of the grains in the bag should be crushed. If you don’t have access to a malt mill, be sure to get the grains crushed at your homebrew shop.

To perform your partial mash, heat some water to between 150° and 158° F. You should have enough water to completely submerge the grains. Add the bag of crushed specialty grains and pale malt to the water. Let the bag soak undisturbed for an hour. Try to keep the temperature between 150° and 158° F. It is more important to ensure the temperature doesn’t rise above 158° F than it is to ensure that the temp doesn’t fall below 150° F.

After an hour, remove the bag and place it in a large kitchen strainer. Hold the strainer over your partial mash water. With a large cup, scoop mash water and slowly pour water over the grain bag to rinse the grains. (It really helps to have a brewing partner for this step — one person holds the strainer with the grain bag in it, the other pours the water through the bag.) Keep rinsing until the water falling from the strainer is the same color as your brewing water. When you are done, take a fine kitchen strainer and strain out any husk material. Add this water to your brew kettle.

##### Step Four: Converting Adjuncts

Adjuncts come in many forms, but to a brewer they fall into two classes, sugary or starchy. Adjuncts comprised mainly of sugar, such as honey or molasses, can be added directly to beer after the mash, during the boil or secondary fermentation. For these adjuncts, add the same amount of the adjunct as the scaled all-grain recipe calls for. Follow the directions regarding their use in the original recipe.

In all-grain beers, starchy adjuncts must be mashed to convert the starches to sugars. Left unconverted, starch can cloud beers. It can also be a carbon source for spoiling bacteria and wild yeasts. Extract brewers have two options when dealing with an all-grain recipe with starchy adjuncts. First, they can see if an extract version of the adjunct is available. Alternately, for small amounts of the adjunct, they can perform a partial mash. If the all-grain recipe calls for a large amount of an adjunct for which there is no extract equivalent, you may not be able to convert the recipe to an equivalent extract recipe. If you know something about the flavor of the adjunct, think about possible substitutions.

In light American lagers, 30 to 40 percent of the mash is either flaked corn or rice. These adjuncts don’t have the enzymes to convert their starch to sugar on their own. So, they are mashed with grains, which have enough enzymes to convert their own starch plus starch from other sources. In order to have enough enzymes to mash starches, a good rule of thumb is to use an amount of pale malt in the mash equal to the amount of starches.

For an extract brewer to use a partial mash for a light American lager, his mash would have to provide 60 to 80 percent of the fermentables. In this case, why not just go all-grain? Fortunately, popular styles of beer with large amounts of adjuncts are often available as liquid malt extracts. For this example, light malt extract designed for American, Canadian or Australian light lagers would be a good substitute for a recipe that called for pale malt and corn or rice. See the later sections for how to calculate the appropriate amount to use.

To perform a partial mash, follow the same procedure as in the section on specialty grains. If the recipe has both a starchy adjunct and specialty grains, combine these ingredients in a single partial mash. For example, let’s say you are brewing a stout with flaked oats (a starchy adjunct) and roasted barley (a specialty grain). Use the same amounts of oats and roasted barley as the scaled all-grain recipe calls for. Add an amount of crushed pale malt to equal the combined weight of the other two ingredients and perform your partial mash.

##### Pale Malt

Up to this point, the conversions from all-grain to extract have been simple. When converting the malt portion of the all-grain recipe, things get a bit more complicated.

So far, we’ve converted the specialty grains and adjunct portion of the all-grain recipe and made a partial mash with some pale malt. At this point, we will make a simplifying assumption. We’ll assume that our extraction efficiency in the partial mash is equal to the original brewer’s efficiency. Now, all we need to do is convert the remaining pale malt to malt extract and we’re finished with the recipe conversion.

Is this a good assumption to make? Well, no and yes. It’s not really likely that your extraction efficiency is going to be exactly the same as the original brewer’s efficiency. But it’s likely to be similar, so — considering that the partial mash is a small percent of the total fermentables — the difference in gravity is likely to be small.

Now, all we need to do is convert the remaining pale malt to an equivalent amount of malt extract. Unfortunately, there is no single conversion factor you can use to get the correct amount of malt extract, because pale malt yields a different amount of fermentables in the hands of different brewers. So first you have to calculate how much the all-grain brewer got from his malt; then you can convert his pale malt numbers to extract.

There are three steps to converting an amount of pale malt used in a recipe to an equivalent amount of malt extract. The first is calculating the extraction efficiency of the original brewer. The second is using the brewer’s efficiency and the potential extract rating of the malt extract to come up with a conversion factor. The final step is to multiply those two numbers together. Extraction efficiency is calculated using the following equation:

Equation 1:
EE =[SGP x V]/W

SGP is specific gravity points, the decimal portion of specific gravity. A wort with a specific gravity of 1.043 would have 43 specific gravity points per gallon. V is the volume of beer produced, in gallons. W is the weight, in pounds, of the grain. Extraction efficiency gives you the number of gravity points you obtained from each pound of grain. For simplicity, add the weights of all your grains and mashed adjuncts together for this calculation.

For an example of how to calculate an extraction efficiency, let’s say you brewed a 5-gallon batch of pale ale using 7.5 lbs. of pale malt and 0.5 lb. of crystal malt and your original gravity turned out be 1.040. Your extraction efficiency would be:

EE = (40 x 5)/8.0 = 25
gravity points/lb. grain

As shown in the table at the start of this story, dried malt extract yields 45 gravity points per pound of grain. Liquid malt extract yields 38 gravity points per pound of grain.

A note on the extract-potential figures in Table 2: These are typical figures, taken from a variety of sources that all agreed within a few points. Actual extract potential per pound varies depending on how the manufacturer made the product (malt extracts contain different amounts of water). You can check to see if information is available for the specific malt extracts you use, but as the saying goes, these figures are definitely good enough for government work!

So, to calculate the amount of dried malt extract to substitute for pale malt, multiply the amount of pale malt times the original brewer’s extraction efficiency divided by 45 (EE/45). To calculate the amount of liquid malt extract to substitute for pale malt, multiply the amount of pale malt times EE/38. For example, using numbers from the previous example, 8.0 lbs. of pale malt equals ((25/45) x 8.0 =) 4.4 lbs. dried malt extract or ((25/38) x 8.0 =) 5.3 lbs. of liquid malt extract.

If you want to skip the EE calculation, assume an extraction efficiency of 30. Unless the brewer gets exceedingly great or exceedingly poor extraction, you will be close.

If the all-grain recipe contains unmashed adjuncts, you will need to use the following formula: EE = SGP x V – [Wadjunct x EPadjunct] / (Wgrains). You can look up the extract potential of the adjunct (EPadjunct) in Table 2 shown at the start of the story.

##### Wheat or Munich Malt

What if the recipe contains a substantial portion of Munich malt or wheat malt? If the recipe contains Munich malt, malt extracts made from 100% Munich are available. Simply convert the Munich malt to Munich malt extract as you would convert pale malt to pale malt extract.

If the recipe contains large amounts of wheat, you’re not so lucky. Malt extracts for brewing wheat beers are made from mixtures of wheat malt and pale malt. If you know the percentage of wheat malt to pale malt in the extract, you can add a mix of wheat malt extract and pale malt extract to match the all-grain recipe’s mix of wheat malt and pale malt.

There are four steps to doing this. First choose a malt extract that contains a higher percentage of wheat than the recipe. Second, calculate the total amount of wheat malt extract you need. Third, calculate how much wheat malt extract you need to add to get that amount of pure wheat malt extract. Finally, calculate how much pale malt extract needs to be added to establish the original balance.

Let’s say the all-grain recipe calls for 5 pounds of wheat malt and 5 pounds of pale malt, a 50:50 mix. Let’s also say that you find a wheat beer malt extract made from 70% wheat and 30% pale malt. You calculate that you need 4 pounds of wheat malt extract and a corresponding 4 pounds of pale malt extract. To get 4 pounds of wheat malt extract from the 70% mixture, you need 4/0.70 or 5.7 pounds of the wheat beer malt extract. This means you also have (5.7 x (.30) =) 1.7 pounds of pale malt extract along with the wheat malt extract. Subtract this 1.7 from the 4 pounds total you needed. You would need to add (4-1.7 =) 2.3 additional pounds of pale malt extract to end up with a 50:50 mixture of extract from wheat malt and pale malt.

##### Yeast

The extract beer from your converted recipe should taste very similar to the original beer if you follow the instructions as closely as possible. But the most important variable may be the yeast. Use the same yeast as specified in the all-grain recipe, pitch enough yeast (this means making a starter) and control your fermentation temperature. Two beers made from the same wort, but fermented under different conditions, can taste very different.

##### What About Extract to All-Grain?

You can convert most all-grain recipes—except those with large amounts of unusual starchy adjuncts—to an equivalent extract recipe. But can you do the reverse? In many cases, the answer is no. If the extract beer uses a malt extract made from a mix of grains, and the mix of grains isn’t specified, you can’t convert from extract to all-grain. For example, if an extract brewer used 5 lbs. of stout malt extract, you may have no idea what mix of grains were used to make the stout malt extract. (You could, however, use the hopping schedule the extract brewer used.)

If the extract brewer has formulated an “all-grain-like” recipe, a recipe where the fermentables are supplied by pale malt extract and the darker colors are supplied by steeping or partial-mashing specialty grains, you can convert the recipe to all-grain. Basically, you just “reverse” the equations in two steps. The other steps are the same. For example, you will end up using fewer hops than an extract brewer would use if he boils a concentrated wort. To calculate the correct amount to use, multiply the amount of hops used in the extract recipe by hop extraction rate for your all-grain wort gravity by the hop extraction rate for the concentrated wort gravity. To convert from malt extract to pale malt, you would multiply the amount of extract by either 45 divided by your extract efficiency for dried malt extract, or 38 divided by your extract efficiency for liquid malt extract.

##### Can You Really Clone a Beer?

Using these steps you should be able to calculate an extract equivalent recipe for almost any all-grain recipe. But, will the beer taste exactly the same? Well . . . no. An experiment published in Brewing Techniques showed that different breweries could not produce identical beers even when they used identical recipes, ingredients and procedures. However, your beer should be similar in taste. And after a few rounds of brewing your beer, it may be better than the original!

Issue: March 2001