Brewer: Tom Flores, Brewer’s Alley in Frederick, MD
Texture is a major component of beer flavor that is often overlooked. Taste and aroma seem to get all the attention, but appropriate texture in beer is just as important. A couple of synonyms for texture that are more commonly used are body and mouthfeel; I use them all interchangeably.
In conversation with fellow brewers regarding beer texture, the aim is often to increase body and avoid the perception of “thin” mouthfeel. I understand this focus, but with respect to mouthfeel, more is not always better. The level of texture should always be evaluated in terms relative to what is appropriate for a beer’s overall flavor composition. Maybe the focus of avoiding “thinness” is due to the fact that it is more of a challenge to increase mouthfeel than it is to diminish it.
Whatever your intentions are for the mouthfeel of your beer, the key to manipulating beer texture is an understanding of the physical property of viscosity. The viscosity of a solution is determined not only by how much “stuff” is dissolved into it, but also by the nature of this “stuff.”
In specific technical language, this translates to: “Viscosity is determined by the concentration of a solute, as well as the molecular weight of that solute.” You can end up with two beers of the same intrinsic viscosity — one which has a high concentration of low-molecular weight solutes (i.e., various sugars like maltose, glucose, etc.) and the other with only a little bit of some very high molecular weight material (i.e. betaglucan, arabinoxylan, etc.).
In the end, the raw material which will have the greatest impact on the texture perceived in beer is the grain you are using. There are some other factors which can affect how you sense viscosity on your palate, but which do not have a big impact on the intrinsic viscosity. For example, glycerol production by yeast during fermentation can lend a certain “slickness” to the texture of a beer.
So manipulation of viscosity is at the heart of controlling body and mouthfeel. You may be looking for some guidance on how you achieve this control. Since beer has so many things dissolved in it that could potentially affect viscosity, I’m sorry to say that there is no single method of approach. However, the most effective way to start adjusting viscosity in either direction is to focus on the high molecular weight material. To accomplish this, most brewers try to control the amount of beta-glucan and dextrinous material (produced from the degradation of starch during the mash). The effect of beta-glucan is well known and generally agreed upon within the brewing community, but that of dextrinous material is subject to some dispute. I guess you could say that it’s hard to draw the line between where starch can no longer be called starch and should be more properly referred to as dextrin. I believe that it is possible to have dextrinous material in wort at the end of a mash that is not near the molecular weight of starch, but is of sufficiently high-molecular weight to influence wort viscosity.
All this adds up to the take home message: Higher mash temperatures (low fermentability/high dextrin content) generally yield a fuller bodied beer in the end, and lower mash temperatures (high fermentability/low dextrin content) generally yield a drier and thinner beer. This approach is fairly well known and easily exploited.
The great thing about homebrewing versus commercial beer production is the lack of headaches for a 5 or 10-gallon (19 or 38-L) system. Beta-glucan is generally viewed by professional brewers as a problematic material to be avoided, and for good reason. Too much beta-glucan (especially high-molecular weight beta-glucan) can lead to stuck runoffs, plugged filters and gelatinous sediment in finished beer. But a subtle hand in introducing a small amount of beta-glucan can actually have a positive effect on body, as well as head retention. Common sources of increased beta-glucan in wort include: rye, unmalted barley and oats. If you use oats, it is important to use pre-gelatinized oats in the mash, unless you are going to cook them separately before adding them to the mash. Good luck!
Brewer: John Dean, Blind Tiger Brewery in Topeka, KS
When I think of boosting body and mouthfeel on a particular beer, I start with the yeast. This may sound like we are starting at the wrong end of the brew day, but it is the yeast’s ability to ferment that will largely determine the body and mouthfeel left behind in that brew. This ability is measured by attenuation. Yeasts available at homebrew shops will have this value printed on the package.
American ale strains tend to be strong attenuators and hang around the 73–80% range. English strains get as low as 63–70%, while some Scottish strains drop to 60% attenuation. Now we go back to the beginning of the brew day, the malt bill. Dextrin is the key to making your American ale yeast behave like it is English. Dextrin is made up of polysaccharides from starch that will lend body and mouthfeel to any beer. It is sold in a powdered form that you can add right to the boil. There are also very pale caramel malts, such as Carapils and Carafoam®, that are specially produced and can be used to boost the dextrin content of wort.
You can use up to 20% Carapils and Carafoam®, but I find 8–10% gives me the desired effect. There are other malts available to help build body. Munich malt is a great body builder and can be used in large quantities. Don’t be afraid to replace some two-row base malt with Munich. With some brands of Munich malt you can use up to 100% in your malt bill! I brew several beers in the 80 to 100% ranges. Crystal malts can add sweetness and body but with a much bigger impact on flavor and color.
The way we manipulate what happens in the mash tun can help us in our endeavor too. Our goal for building body and mouthfeel is a thick mash. A thin mash increases the proportion of maltose, which will lead to greater attenuation (and a thinner body). Next we want that mash to land in the 158–162 ºF (70–72 ºC) range. A saccharification rest at this temperature will produce wort rich in dextrin. You want to keep mash pH in the 5.3 to 5.5 range. Your last runnings should not fall below SG 1.008 or you could extract tannins, which are astringent and can add to mouthfeel.
As far as hops are concerned, it is often the case that really hoppy beers require more malt backbone to prevent the beer from becoming unbalanced and perceived as thin-bodied. If you’re happy with your grain bill, you can also alter your choice of hops to boost mouthfeel. Going with some low cohumulone varieties is always a good choice.