Brewing with Oatmeal
When you say the word, “oats” to a brewer, most often they think of oatmeal stout. But oats are also sometimes used in Belgian witbiers and American stout. In fact, you can use oats in any style you put your mind to. Oats add to the body of the beer and can add a silkiness to the mouthfeel. They take some of roast edge off the palate and are popular in stouts for that reason.
The idea of oats in other beer styles may sound odd to new brewers — they have heard of adding wheat for head retention, but oatmeal? As such, they may ask: How do I make beer with that? Do I just dump it in? What kind do I use? Oh wait, it’s probably some special kind of oats from the health food store, or maybe it has to be malted oats.
The answer to this question is “E: All of the above.” Oats are very similar to barley and can be processed in the same way. Oats can be malted, made into specialty malts or flaked. However, oat malts are not widely available. Thomas Fawcett and Sons in West Yorkshire, UK, and Simpson’s Malts Ltd, Northumberland, UK, are the only remaining maltsters of oats, producing a lager-type base malt and a de-husked light crystal malt respectively. Flaked oats are widely available though, both as a brewer’s adjunct and in the breakfast section of the grocery store.
Let’s review a little bit about using cereal grains, though, before we slap down our hard-earned money on a bulk bag of rolled oats at Costco. First off, oats and oat malts need to be mashed, exactly the same as barley and barley malts. The oat crystal malt (and oat roast malts, if existent) can be steeped just like the corresponding barley malts because the starches have been gelatinized during the kilning and roasting process after malting.
Oat malt is similar to barley malt in most respects, but it has two differences — it is higher in protein, and it seems to yield a sweeter tasting wort than barley. The difference in sweetness is probably due to a difference in tannin character between the two grains. These differences work well with stouts and porters, but it can also be useful in making session beers; adding body and a little more flavor to a 1.035 light lager for instance. The higher protein content can also boost head retention, similar to wheat. Table 1 shows a comparison of oat and barley brewing properties.
You will often read that you can add rolled oats directly into the mash, i.e., that they don’t need to be cooked. And it is true; the starch gelatinization temperature of oats is 127–138 °F (53–59 °C), which means that the starches will hydrate and react with the mash enzymes at mash temperature. If the starches were not water soluble, the enzymes would not be able to act on them. Rice, for example, has a gelatinization temperature of 154–172 °F (68–78 °C), which is higher than most mash temperatures. Adding crushed rice to a typical mash would result in very little of the rice starch being converted – it would just sit there. In order to make the starches water-soluble, rice needs to be heated above the gelatinization temperature range and soak up water — in essence, get cooked. The flaking operation is designed to pre-gelatinize the cereal and reduce the amount of cooking time necessary to get all of the starches fully hydrated and soluble.
The flaking process starts with whole oats that have been de-hulled (or de-husked) leaving an oat groat. The groat consists of the starchy endosperm of the oat surrounded by the bran (otherwise known as the aleurone layer and pericarp). You can get barley groats too, but more often you will find “pearl” barley in the grocery store, in which the bran has been removed from the groat as a second step. The oat groats are soaked in water to increase the moisture content and soften them. The groats are steam cooked to varying degrees, depending on the product, and then flattened between two large heated rollers set to 0.010–0.020 inch (0.25–0.50 mm) apart. The oats are dried after flaking to about 9–12% moisture.
In terms of size and ease of use, whole rolled oats are generally the largest and are the least “cooked.” Quick oats are made by cutting the groats into smaller pieces. The smaller size allows more thorough cooking prior to flaking and less cooking required to make oatmeal. Instant oats have been cooked longer or cut into smaller flakes to reduce the oatmeal cooking time even further. Brewer’s oat flakes are typically prepared to a slightly different process to benefit mashing. The groats are infra-red heated instead of steamed, are rolled thinner, and dried to a lower moisture content (7–8% vs. 9–12%). How much difference do these processes make to your beer? The thinner, more cooked oat is more readily mashed, and the infra-red cooking provides a more toasted flavor than steaming. Consider the difference in flavor between steamed and baked bread. For the professional brewer, the lower moisture content means better extract economy.
Oat flakes do not add much flavor unless they are toasted. Toasting can be carried out at various temperatures from 250–350 °F (121–177 °C) depending on the degree desired. The most commonly recommended temperature of 300 °F (149 °C) will develop a rich toast or cookie-like aroma and flavor. Higher temperatures cause roasting and dark toast or coffee flavors. The time necessary is 20–60 minutes depending on the degree of toast. Spread the oats out on a cookie sheet and stir them occasionally while you are toasting. Use your nose and your eyes to determine when they are done.
Let’s assume you are going to brew today with the oats that you have in the cabinet at home, rather than buying brewer’s flakes. You are probably wondering if you should cook them or simply add them to the mash. Cooking the oats ahead of time on the stove does take the guesswork out of mashing with store-bought rolled oats. Consider for a moment the fact that you crush your malts in a grain mill before mashing in order to make the starches more accessible. If you are going to add flaked oats to your mash, especially the larger, old-fashioned rolled oats or the high fiber (i.e., full-bran) rolled oats from the health food store, either cooking them or running them thru your grain mill will minimize the chances of ending up with oat starch in your beer. Smaller pieces means faster hydration and gelatinization, and better accessibility for the enzymes. Without pre-cooking or milling, the rest of the mash may be long done before you get full conversion of the oat starches.
The thing to remember with any adjunct or new ingredient is that discretion is the better part of flavor. Don’t go overboard with oats, in fact I would not recommend over 25% as a general rule. The high protein content and oil in the oat bran can cause a greasiness to the mouthfeel and a mealy taste to the beer if used in excess. If you are using a lot of rolled oats, it may be a good idea to use some rice hulls in the mash or conduct a beta glucan rest at 95–122 °F (35–50 °C) to break up the gums that makes oatmeal so gummy. Oatmeal porridge does not lauter well.
So what sort of beer can we brew with oat malt? Oats are a versatile brewing ingredient and can be used in many beer styles — oatmeal stouts and porters, Belgian witbier, pale ales, session beers, etc. The body and sweetness of oats got me thinking about helles bock, which is known for having a rich malt body and lots of bready malt character. The thought of adding some toasted oat character to the aroma of the beer intrigued me too, and this inspired the recipe below.
Kid Groat Bock
(5 gallons/19 L, all-grain)
OG = 1.064 FG = 1.017
IBU = 28 SRM = 12 ABV = 6.6%
Ingredient
8.lbs. (3.6 kg) Pilsner malt
2.lbs. (0.91 kg) oat malt
3 lbs. (1.4 kg) Munich malt
0.5 lbs. (0.23 kg) Briess Aromatic malt
1 lb. (0.45 kg) home toasted rolled oats
8 AAU German Magnum hops (60 min.) (0.62 oz./17 g of 13% alpha acids)
White Labs WLP833 (German Bock Lager) or Wyeast 2206 (Bavarian Lager) yeast
3/4 cup corn sugar (if priming)
Step by Step
Toast the oats at 300 °F (149 °C) for 30 minutes, until they smell like cookies. Mill oats with grains and step mash at 130 °F (54 °C) for 15 minutes, and then ramp to 155 °F (68 °C) for 45 minutes. Boil for 90 minutes. Ferment at 52 °F (11 °C).
