Adding Body to your Stout
A recent article in an advice column from one of the major US homebrewing magazines commented on how to add body to your stouts. The article provided some advice, but it missed the opportunity to comment on one of the most prevalent causes of thin body in dark beers: Improper Water Chemistry.
Beers like porter and stout include a significant proportion of dark grains to give them their color and flavor. Those grains are quite acidic and their contribution can drive mash pH quite low. While we don’t want wort pH to be greater than about 5.6 for any wort, we don’t want that pH to get too low either. One reason is that low pH enhances the performance of Proteolytic Enzymes in the mash that literally chop up the wort’s long and medium length protein chains into tiny “bodyless” remnants. Too much of that activity is the main cause of thin beer.
There are a couple of ways to avoid this low pH problem. The first is to simply have enough alkalinity in your mashing water to neutralize the extra acidity from the dark grains. Ideally, you want to keep the mashing pH for a dark beer somewhere in the 5.4 to 5.6 range to avoid excessive proteolysis and to help smooth and enrich the roasty flavors of the dark grains. Wort pH falling below 5.4 produces more acrid and sharp roast flavors that aren’t as pleasant. If your tap water has natural moderate to high alkalinity, you probably don’t need to worry about low mashing pH. But if your water has low alkalinity (like RO or distilled water), then you need to plan on adding alkalinity to the mashing water with additions such as baking soda or pickling lime. Either of those salts add the alkalinity that those waters lack.
A second method for preserving and aiding body in your dark beers is to remove the dark grains from the main portion of the mash and add them late in the mash so that they won’t have the time to chop up your wort’s valuable long and medium chain proteins and preserve their body building power. One problem with this method is that the wort pH still falls pretty low and that can leave the roast flavors more acrid and sharp. Additionally, more of those dark grains will need to be added at that late point in the mash in order to produce the same level of roasty flavors if they were added with the base grain mash in.
In a way, the second method is how Guinness produces their stout. The Dublin, St James Gate brewery gets most of its water from the Wicklow Mountains south of the city. That water actually has very little mineral content at all, and most importantly, it has very low alkalinity. Guinness mashes the pale malt and raw barley together to create the backbone of their beer. That mash is conducted in a typical pH range and is not degraded by excessive proteolysis. They separately steep the roast barley using their low alkalinity water which creates a very acidic and dark extract that they call “Guinness Flavor Extract”. They blend that extract into their regular wort to formulate the beers they want. By separating those components, they avoid the problems caused by a low mashing pH and they still produce a crisp and acidic dry stout that has high body from the raw barley’s high beta-glucan contribution. Guinness perfected a dark beer that worked with their low alkalinity water source.
So instead of boosting your grain bill or incorporating nitrogen gas dispensing as recommended in that homebrewing magazine article, the most beneficial way to enhance beer body is to make sure your mashing pH falls in the desirable range of 5.4 to 5.6. That is how to preserve body in dark beers.