Body Builders
As an avowed fan of rich, dark beers like porters and stouts, a big body and mouthfeel is something I’ve focused quite a bit on in my 38 years as a homebrewer. In addition to the malt/hop balance, overall aroma and flavor, body is one of the critical features you must get right to achieve perfection in a beer.
This is not to say that all beers should be full-bodied. Many lagers, session, and summer beers require a thin, light body to maximize drinkability. The key, of course, is to match the body to the style and effect you are trying to achieve in the finished beer so the whole is greater than the sum of its parts.
Mouthfeel vs. Body
The terms “mouthfeel” and “body” are often used interchangeably in brewing, and indeed it is hard to separate them. Mouthfeel is perhaps the broader term, being defined by Merriam-Webster as “the sensation created by food or drink in the mouth.” I like this definition as it captures the perception of beer in the mouth, which may be a combination of many ingredients, chemical reactions, and techniques.
In contrast, Merriam-Webster defines “body” as “fullness and richness of flavor,” or alternately “denseness, fullness, or firmness of texture.” This is a somewhat narrower definition, as one might imagine a thin-bodied beer that is still rich in flavor. Body and flavor are not necessarily synonymous in my mind.
I think the key point here is that it is the perception of body that matters most. Individual aspects of the beer like finishing gravity, bitterness, carbonation, flavor, and unfermented sugars all drive the mouthfeel and body of the beer, but it is the combined effect on the drinker that matters.
The body of beer cannot be easily measured, as it is an overall perception and not a number from a machine. One needs to sample a beer to determine its body. When judging the body of beer, it is common to speak of a scale that varies from thin- or light-bodied beers to medium-bodied, to rich- or full-bodied beers.
Contributors to Beer Body
The perceived body of a beer is driven by many factors. We will explore each of these in more detail, but I want to first introduce some of the key drivers:
Carbon Dioxide (and Nitrogen) – The carbonation level of the beer drives its perceived body. Beers higher in carbonation have more mouthfeel and are perceived as having more body. Beers like Guinness that are carbonated with a nitrogen mix have even more mouthfeel than beers carbonated with just CO2.
Foam – Related to carbonation, a beer with a creamy head of foam is perceived as having more body. Interestingly, polyphenols from both malt and hops play a role in foam retention, so beers high in hops can be perceived to have more body.
Proteins in Malt – All malts and grains contain some level of protein, and protein is one of the biggest contributors to perceived body. Beta-glucans and gums in malts also contribute body to a finished beer.
Unfermentable Sugars and Carbohydrates – A portion of the complex carbohydrates from grains are typically not completely broken down into fermentable sugars in the mash and remain as residual carbohydrates. Like proteins, these long chains of sugars contribute mouthfeel and body to the finished beer.
Yeast Selection – Yeast selection drives the attenuation and fermentability of the beer, but it also drives the overall flavor profile, which can affect the perception of body. Even residual yeast itself can be used in suspension for beers like hefeweizen to increase the perception of body.
Alcohol and Gravity Level – Beers higher in alcohol create a warming sensation in the mouth and are perceived as having more body. A high starting gravity produces more alcohol for a given yeast strain, increasing the perception of warmth and body.
Tannins – Tannins are a naturally occurring plant compound found in both malt and hops. In the mouth, tannins are attracted to proteins in our saliva and react with these proteins and coagulate, creating a sensation known as astringency. Astringency creates a dry, crisper mouthfeel for the drinker, though in excess they can be distasteful.
Dark Malts – While many beer drinkers think that dark beers inherently have more body, this is not always so. However, dark malts do have a higher level of unfermentable sugars. This is because dark roasted, caramel, and kilned malts have converted some of the fermentable sugar chains into unfermentable as part of the roasting process.
As I mentioned earlier, the goal with a certain recipe could be a full-bodied beer, very light-bodied beer, or anything in between, so you need to consider all of these factors in combination when designing a beer. Having covered the basic factors, we can now dive into each individual factor in more detail.
Carbonation and Foam
The level of carbonation drives the mouthfeel and perceived body of beer. Higher carbonation levels like those used in many Continental European beers will increase mouthfeel, while low carbonation will reduce it.
If you take the extra step of using a nitrogen/carbon dioxide mix, also called a stout mix, to carbonate your beer as draft Guinness does, it will enhance the perception of body even more. It’s interesting to note that draft Guinness has a relatively low original gravity and alcohol level, but the addition of a large portion of flaked barley, dark malts, and nitrogen mix carbonation creates one of the biggest mouthfeel/body perceptions of any beer.
Foam also plays a huge role in the perception of beer body. The captured CO2 bubbles at the top of the beer provide mouthfeel when you sip the beer. Proteins and dextrins, will enhance the head retention in a beer. However, many brewers don’t realize that hops also play a role. Alpha acids, which are the primary bittering compound in beer, enhance head retention, as do polyphenols from the hops themselves. A very hoppy IPA will have better head retention than a lightly hopped session beer.
Malt Selection and Protein Levels
Protein is one of the easiest factors to control since the malt data sheet for a given malt will typically show the protein percentage. If targeting a big, rich-bodied beer you can use malts with higher protein levels. Obviously, low protein levels are desirable for light-bodied beers.
One note of caution, however, is that proteins also tend to reduce clarity in light-colored beers, so if you use a bunch of high-protein adjuncts in your beer it can cause serious clarity issues. Looking at protein numbers from various maltsters, several things stand out. Unmalted grains such as flaked oats, flaked or torrified wheat or barley, and black (stout roast) barley all have the highest percentages of proteins. Below that we have caramel and crystal malts like Carafoam®, Caraamber®, and various colored caramel malts. Next come the darker roasted and kilned malts.
If your goal is to have less body and less protein, the lighter base malts like Pilsner are a good choice. Not surprisingly, 6-row barley varieties have higher protein levels than 2-row varieties. Also, American barleys tend to have a higher protein content than their European cousins, though some traditional British malts do have high protein levels.
Unfermentable Carbohydrates and Mashing
Yeast will consume simple sugars like maltose and glucose, leaving more complex carbohydrates untouched. Because we can influence the amount of unfermentable sugars remaining post-fermentation through our choice of malts, mash temperature, and yeast, we can drive the attenuation of the yeast and how much body remains.
Malt selection again plays an important role. In addition to considering how much protein a malt has, we also want to consider how much unfermentable sugars like dextrin the malt contains. For example, malts like Carafoam®, Carapils®, dextrin, and chit contain more dextrins and are often used to add body to beer. Unmalted adjuncts like flaked barley and flaked oats also contain a high percentage of unfermentable sugars. As will be covered later, dark malts also have a lower percentage of fermentable sugars because many of the fermentable sugars are broken down during roasting and kilning.
The next factor a brewer can easily control is mash temperature. Because the two major enzymes — alpha and beta amylase — reach their peak effectiveness at different temperatures, you can adjust your mash temperature to promote more or less fermentable sugars and therefore drive a lower or higher body in the finished beer.
Selecting a high mash temperature around 156–158 °F (69–70 °C) will create less fermentable sugars and create a beer with a full body. Using low mash temperatures in the 148 °F (64 °C) range will promote more fermentable sugars leaving a lighter body in the finished beer. If you hold steps at both temperatures, often called a lager mash profile, you can promote even more fermentability and less body than just mashing the low temperature range.
Yeast Selection
Another consideration is the choice of yeast strain. Each yeast strain has a published “attenuation” parameter as part of the yeast data sheet. Attenuation is the “apparent” percent of sugars that are fermented by the yeast strain in a standard wort. Yeast labs usually list the apparent attenuation, which differs from the real attenuation only in the fact that real attenuation is corrected to account for the fact that alcohol has a gravity below 1.000, while the apparent attenuation can be measured directly. The average attenuation for many yeast strains is around 70%.
If you choose a yeast with low attenuation, it will leave more body in the finished beer, while a yeast with high attenuation will ferment more of the sugars, leaving a lighter body in the finished beer.
As mentioned earlier, yeast itself can also play a role in the body of the beer. Fresh, green beers served early will still have yeast in suspension, adding to cloudiness but also enhancing the perception of body in the beer.
Perhaps the best commercial example of this is the hefeweizen style from Germany, which is a wheat beer served “with yeast.” This beer is bottled with the yeast sediment, and the server will pour some of the beer off the top and then swirl the bottle around to get the yeast back into suspension before pouring the rest into the glass. The suspended yeast adds considerably to the flavor and body of the finished beer. Another great example is the hazy IPA style, which relies on yeast in suspension, in part, to provide the haze and enhance the body of the finished beer.
Alcohol and Gravity Levels
The warm flavor from high alcohol levels tends to enhance the perception of mouthfeel. A low-gravity light summer or session beer will have less perceived body than a high-alcohol strong ale.
Alcohol in your beer is primarily driven by your starting gravity and choice of yeast, which drives the attenuation. A higher starting gravity beer will drive higher alcohol levels for a given yeast strain. Therefore, raising the starting gravity of your beer is a simple way to also increase the body since a given yeast strain will only ferment a roughly fixed percentage of the sugars.
Selecting a higher attenuating yeast will also drive higher alcohol levels. However, in an interesting twist, higher attenuation also leaves less body in the finished beer in the form of unfermented sugars. If you choose a high attenuation yeast you may get more alcoholic warmth without substantially raising the perception of body since the beer will have less unfermented sugars. So, the entire effect you are trying to create in terms of body, flavor, and balance needs to be considered.
As you drive the alcohol level up to very high levels, overall balance becomes a consideration. First, as you drive gravities and maltiness up, you need to add more hops to achieve the right balance. Second, you really need plenty of body and flavor in a high-gravity beer to offset and balance the alcohol warmth or the alcohol will come across as harsh.
Conversely if you consider non-alcoholic or low-alcohol beers, many of these styles suffer from a lack of body because the alcohol we expect to be in the beer has been removed, throwing the body out of balance. Great lengths often must be taken to add body to a low- or non-alcoholic beer to achieve a normal body and flavor balance.
Tannins
Tannins are found naturally in both grains and hops as well as fruits and even tree bark. They work as a preservative in beer and foods. Tannins are extracted from malt husks during mashing, and extracted from hops in the boil, whirlpool, and dry hopping.
As mentioned earlier, tannins combine with proteins in our saliva causing them to coagulate in your mouth, creating a sensation known as astringency. In moderate doses this reaction can create a perception of additional body. It also creates a dry, crisp mouthfeel, which can be an advantage with certain styles.
However, if you add too many tannins, you can create a harsh flavor akin to sucking on a tea bag. In addition, some people are more sensitive to tannins than others, so excess tannins can be very off-putting to some drinkers.
Tannins from malt are highest in what we call the “harsh zone” malts. Harsh zone malts are malts in the color range of 70–200 Lovibond, including malts near the edge like light chocolate malt and brown malt. If you use malts in this range sparingly, at only a few percent of the total malt bill, you can create great flavor depth as well as additional body. Raising the percentages higher, however, risks creating harsh astringency in the finished beer.
Tannins are also present in hops, so highly hopped IPAs will have more perceived body than a comparable beer with fewer hops. As with malts, over hopping a beer runs the risk of introducing harsh astringency into the beer and often also introduces vegetal off-flavors, so achieving proper balance in a hoppy beer is important.
Dark Malts
As mentioned in the introduction, dark malts have fewer fermentable sugars, which can be used to drive the finished gravity higher creating additional body. Several studies (cited here) show drops as large as 25% in attenuation when using a high percentage of dark malt (as high as 50% dark malt).
While adding 50% roast malt to a recipe is extreme, the studies mentioned above have shown a consistent relationship between the use of darker malts and lower fermentability. This makes sense as the kilning and roasting process will break down some of the carbohydrates in the malt into a form where they are no longer fermentable and therefore survive fermentation as unfermented residual sugars.
When we combine this lower fermentability with the presence of higher tannins as well as melanoidins (color compounds) from the kilning or roasting process, the overall effect of using dark malts in your beer is to enhance the body of the finished beer. Conversely, lighter-colored beers tend to be perceived as lighter in body.
Conclusion
I’ve provided an array of tools to enhance or reduce the body of your finished beer. The key to using them is often combining several techniques rather than relying on just one. The classic example is Guinness, which includes a high percentage of flaked barley, unmalted stout roast malt that adds a dry coffee-like finish, and a nitrogen and CO2 stout mix to carbonate the beer. Despite the low alcohol level and low starting gravity, Guinness has a great deal of mouthfeel.
No matter whether you are targeting a full-bodied beer or light summer ale, balance is the key. Going overboard on the use of hops, tannins, alcohol, dark malts, yeast, carbonation, or any single technique will likely result in an unbalanced beer. However, combining several of these techniques in moderation can deliver exactly the body and mouthfeel you want for your next brew.
