How To Brew an Oatmeal Stout (Recipes, Water, Mash, Boil, Fermentation)

Oatmeal stouts were once erroneously considered a health drink. While you shouldn’t have an oatmeal stout for your health (or for breakfast!), you still may want to know what goes into it. How do you brew an oatmeal stout?

When brewing an oatmeal stout, start with classic stout ingredients, including water with a high chloride-to-sulfate ratio, English ale yeasts, English pale malts, and English aromatic hops. Combined with oats and chocolate malts, these ingredients will result in a creamy-bodied beer with notes of chocolate, coffee, caramel, and roasted malts.

If that sounds like the type of beer you’d enjoy brewing and drinking, keep reading to learn all about the style. I will cover all of the important aspects of the recipe and instructions.

What is an oatmeal stout?

Stouts come in many different shapes and sizes. One of these many styles is defined by the use of oats in the grist. The addition of oats – whether flaked or malted – provides a fuller body for the stout to build upon.

As this is the defining characteristic, there is a lot of room for interpretation of the style. Some oatmeal stouts are more bitter than they are sweet and vice versa. Some lean into the breakfast concept and emphasize coffee flavors. Yet others add in some light fruitiness.

Like the oats they are made from, oatmeal stouts are known for their creamy mouthfeel and mild sweetness. The style is dark in both coloration and flavors but can encompass many different characteristics:

  • Color – Dark brown to black, 22-40 SRM
  • Common flavor – Roasted malts, coffee, nuts
  • Aroma – Coffee, malt sweetness, roast malts
  • Mouthfeel – Medium carbonation, creamy, smooth
  • IBUs (Bitterness) – 25-40
  • ABV – 4.2-5.9%

History of the oatmeal stout

Like all stouts, this style came first from the English porters. In the many years since the two styles diverged, several substyles have developed. Dry, milk, imperial, Irish, and oatmeal stouts all share some similarities as stouts. That said, there are enough differences to make them unique.

Stouts have been a unique style since the 18th century. Oatmeal stouts came a little later with the first recorded example in 1894. The style enjoyed popularity for several decades before fading. It was revitalized in the 1980s.

To learn more about the history of oatmeal stouts, check out this article.

Popular commercial oatmeal stouts

Are oatmeal stouts starting to sound good? Pick one up and give it a try!

To get an idea of the style, here are some commercial examples you can try:

  • Fremont Brewing Company The Rusty Nail – If you like imperial stouts, this imperial oatmeal stout is for you. Sitting at 13.3% ABV, this beer provides depth with malt sweetness, cinnamon, licorice, and espresso flavor notes.
  • Samuel Smith’s Oatmeal Stout – A lighter beer at 5% ABV, Samuel Smith’s Oatmeal stout has notes of caramel, chocolate, and fruits.
  • Founders Brewing Company Breakfast Stout – This oatmeal stout leans into the coffee notes in addition to the roasted malt flavors. With these flavors, it provides a nice balance between sweet and bitter flavors.
  • Ohio City Oatmeal Stout – Another well-balanced oatmeal stout, this one has notes of chocolate, caramel, and roasted malts.

How to brew an oatmeal stout

Whether any of the above was new information or not, now we can get into the fun part. If you want to contribute to the long history of oatmeal stouts you need to know your recipe forward and backward.

Below I will go into detail covering the major ingredients, brewing, fermenting, and packaging. The entire process will take roughly 3-4 weeks depending on how long you let the beer age.

Recipe and ingredients

You can’t make good beer without the right quality ingredients.

This means you need to know what ingredients work best for the style, including:

  • Water profile
  • Base grains
  • Specialty grains or other additions
  • Hops
  • Yeast

This style has a lot of flexibility but let’s go over where to start.

Water profile

For the best oatmeal stout starting point, you want water that supports the malty characteristics.

This means your chlorides should be higher in ratio to your sulfates. Additionally, stouts tend to drop the pH significantly so tailor your water to reduce that pH drop.

Most stout water profiles will work for an oatmeal stout. Choose a water profile that best complements your goals. Use water profiles for milk stouts if you want a sweeter stout. 

Taking the time to figure out your water profile and modify it or start blank with RO (reverse osmosis) or distilled water will elevate your beers. After all, beer is 90% water.

Base grains

You have to have oats in your grain bill of course, but oats should not make up your entire bill. You still need some base grains to support the oats.

A good base grain for the majority of the grist is an English pale malt. Maris otter is a great choice for oatmeal stouts. This malted barley will provide a nice nutty flavor to the beer.

This grain can make up roughly 80% of your grain bill. You’ll need at least 5% oats so the rest will depend on your goals for the stout. You can use more than 5% oats for further creaminess. 

Other great choices for base grains include:

  • US pale 2-row malt – Provides light grain flavors
  • German pale ale malt – Provides decent malt flavors

Specialty grains or other additions

These grains will fill up the rest of your grain bill. For a stout, you want dark roasted malts that provide a lot of color and flavor. 

For an oatmeal stout, you have several choices for specialty grains. You will need either flaked oats or malted oats at 5% of the bill minimum. In addition, you should have dark malts. Chocolate malts are a great choice.

The choice between your oat options is solely up to you. The differences will be minimal. Flaked oats will impart more body than malted oats. Keep in mind that flaked oats can slow your sparge. 

Other great choices for specialty grains include:

  • Special B malts – Provides caramel flavor & aroma
  • Crystal malts – Provides great toasty malt flavors

Hops

Although hops are not the main feature of this style, their inclusion is still important. Hops can provide a balancing bitterness that prevents the malt flavors from running rampant.

When choosing hops for an oatmeal stout, look primarily for bittering hops of medium strength. Hops that complement sweet beers in flavor and aroma are also included in some recipes.

The generally accepted hop choices for this style are English hops. That said, experimentation is the heart of home brewing.

Bittering

Of the two main uses for hops, bittering hops are the simplest. With bittering hops, you can simply add them early in the boil and forget about them. The earlier they are added the more alpha acids are isomerized and the more bitterness they impart.

Since oatmeal stouts don’t require much bittering these hops don’t need to have high alpha acid concentrations. 

NamePurposeAlpha Acid %
East Kent GoldingsAroma5-6%
FuggleAroma2.4-6.1%
Styrian GoldingsAroma2.8-6%
Aroma and flavor

In most cases, this style is more sweet than bitter. To that end, the flavor and aroma of the hops you use should complement that. These hops are added later in the boil as the oils that provide the flavor and aroma are quite delicate.

In an oatmeal stout, you will not need a strong hop flavor or aroma. Choose subtle hops that support the malt sweetness and other malt characteristics. Since the style does not call for hop characteristics you can use just one variety. This removes the concern for compatibility between hops.

NameFlavor/AromaAlpha Acid %
CalicrossEarthy, floral, fruity5.8-7.9%
East Kent GoldingsHoney, thyme, spice5-6%
Fuggle Vegetal, woody, floral2.4-6.1%
Styrian GoldingsEarthy, resin, white pepper2.8-6%
WillametteFloral, fruity, spice4-6%

Yeast

The choice of yeast strain is just as important to this style as the grain bill.

Good yeast strains for oatmeal stouts have medium attenuation, high flocculation, and slight ester production. The yeast should accentuate sweet and malt flavors. If you choose to include fruity flavors your yeast should reflect that.

The ester production of a yeast strain is what will provide some fruity flavors. This is also determined by the temperature you ferment at. If you ferment at the higher range of a yeast strain, you will get increased ester production. 

Both liquid and dry yeast will work for this style. Don’t forget to use a yeast starter before pitching.

Dry

Here are some great dry yeast options for oatmeal stouts.

NameAttenuationFlocculationTemp Range
Nottingham English AleHighHigh50-72°F
Mangrove Jack M07~78%High57-72°F
Safale US-0474-82%High59-68°F
Windsor British Ale65-69%Low59-72°F
dry yeast options for oatmeal stouts
Liquid

Here are some great liquid yeast options for oatmeal stouts.

NameAttenuationFlocculationTemp Range
WLP002 English Ale63-70%Very high65-68°F
WLP051 California Ale V70-75%Medium to high66-70°F
Wyeast 131871-75%High64-74°F
Wyeast 108471-75%Medium62-72°F
liquid yeast options for oatmeal stouts

Brewing process

Brew day can be a busy one. That’s why it helps to have a good idea of everything you’ll need to do. When you’ve got all your ingredients and done all your prep (don’t skimp on sanitizing), you’re ready to go!

By brew day, you should have decided if you’re doing extract, partial, or all-grain brewing. If you are doing partial or all-grain, you’ll have to decide between single infusion or step mashing. You will also need to decide the mash temperature, how much water you’ll need, whether you’re using a yeast starter, and the hop schedule. 

When these decisions are made your brew day will be straightforward. If your grains are not pre-milled your day will start there. From there you’ll mash, lauter, and boil. After that, you’ll cool the wort, transfer it to primary, pitch the yeast, and let the fermentation begin.

Then all you’ve got to do is wait for wort to become beer through the wonders of science! For now, let’s go over all of the details for each step in the process.

Mashing

The mash process is mostly standard for an oatmeal stout, but there is one big difference you should be aware of. As for the mash water temperature, be sure to heat the water to a few degrees higher than you need. This will allow it to cool some as it heats the mash container.

Mashing for an oatmeal stout should be at the mid-range of mash temperature to emphasize the malt aspects. Roughly 154°F should do. Maintain this temperature for a mash of at least 45 minutes. When it comes time to sparging know that the oats will slow the entire process. The more oats, the slower it’ll be.

You want your mash temperature to be slightly higher than other styles to boost the malt characteristics. That said, you don’t want to use too high a temp as the grist is already strong.

The duration of the mash is more up to you. The longer you mash the less sweet the end product will be. If you’re going for a drier oatmeal stout mash for longer and vice versa.

Boil

As with most other styles, your boil should be an hour long for an oatmeal stout. Any bittering hops you use can be added at the beginning of this hour. Aroma and flavor hops should be added no earlier than 30 minutes left.

You can extend the boil if you are going for a higher-ABV stout. If you do so, keep the schedule for the bittering hops at an hour before the end of the boil. Aroma hops should also still be no earlier than 30 minutes left.

Adding the aroma hops later will prevent the oils from boiling off. However, if you don’t give them enough time they won’t be extracted from the hops.

Whirlpool or flameout

While you cool your wort for transfer to the primary fermentation, you can do a few things to help the process.

During flameout, if you create a whirlpool, you can collect all of the trub. This will help ensure the trub does not remain in the wort. Additionally, you can add hops and other aroma ingredients, though this is not as important with an oatmeal stout.

Adding hops during whirlpool will ensure that practically no bittering occurs. The only things the hops will add are aroma and flavor.

Fermentation

The fermentation period for an oatmeal stout should take a week or two. Keep an eye on your fermenter and watch as the bubbling eventually slows. 

When it comes to fermentation, the majority of the process is patience, as with all styles. Where oatmeal stouts can differ is the temperature control.

Temperatures

With an oatmeal stout, start your fermentation towards the lower end of the viable temperature range of your yeast strain, say around 64°F. As the fermentation progresses, slowly raise the temp towards the higher end of the viable range (roughly 72°F).

Incrementally increasing the temperature will ensure that your yeast is active the entire time. Lean towards the higher end of the range if you want to encourage ester production. This is great if you’re aiming for a slight fruit flavor.

Bottling or kegging

While there is no end-all-be-all answer to the question of bottling or kegging, you can benefit slightly from one over the other in this case.

Oatmeal stouts benefit from aging to become fully realized. This means that bottling can be better as you can crack open a bottle throughout the aging process. 

When your batch of beer is split up into smaller portions it is easier to save some for a later date. Of course, it is up to personal preference in the end. If you prefer to age in a keg then that’s what you should do.

Example oatmeal stout recipes and instructions

When you’re first starting out, making your own recipes sounds quite daunting. To help you get started I have a few great recipes. Feel free to modify these recipes as you like.

Grandma’s Secret Stash

This all-grain recipe makes 5 gallons. The final product should have 36 SRM, 5.7% ABV, and 32 IBUs.

Ingredients

  • American – Pale 2-Row – 5 lbs
  • United Kingdom – Golden Promise – 4.5 lbs
  • Flaked Oats – 1 lb
  • Belgian – Biscuit – 0.5 lbs
  • American – Chocolate – 0.5 lbs
  • Belgian – Special B – 0.5 lbs
  • United Kingdom – Roasted Barley – 0.38 lbs
  • American – Black Malt – 0.13 lbs
  • Brewer’s Gold pellets – 0.9 oz
  • Irish Moss – 15 tsp
  • Dark Rum Soaked Raisins – 4 oz
  • Dark Rum & Cinnamon Soaked Vanilla Beans – 2 oz
  • Wyeast 1084

Method

  1. Heat 3.75 gallons of water to 152°F. Then add to the mash vessel.
  2. Slowly add the fermentables to the mash vessel. Stir while adding.
  3. Mash at 152°F for 1 hour.
  4. Recirculate the mash vessel.
  5. Sparge at 170°F for 15 minutes with 3.75 gallons. Collect 6.5 gallons of wort.
  6. Begin the 60-minute boil.
  7. Immediately add the hops.
  8. At 15 minutes left, add the Irish moss.
  9. At 5 minutes left, add the raisins.
  10. Cool the wort to the pitching temperature.
  11. Transfer to the primary fermenter.
  12. Pitch yeast.
  13. Ferment starting at 62°F with incremental temperature increases.
  14. Transfer to secondary.
  15. Add the vanilla beans.
  16. Ferment for 5 days.
  17. Bottle or keg.

Classic Oatmeal Stout

This partial mash recipe makes 5 gallons.

Ingredients

  • Light malt Extract – 5.2 lbs
  • Pale 2-row malt – 1.2 lbs
  • Flaked oats – 0.8 lb.
  • Wheat malt – 0.4 lb.
  • Roasted barley – 0.6 lb.
  • Chocolate malt – 0.2 lb.
  • Crystal malt – 0.6 lb.
  • Northern Brewer hops – 1 oz
  • Wyeast 1084
  • 3/4 cup dextrose

Method

  1. Heat 4 gallons of water to 160°F. 
  2. Pour over the grains and malt in the mash tun and steep for 45 minutes.
  3. Drain wort and rinse grains with another 1 gallon of water at 158°F. Collect 5 gallons of wort.
  4. Add in the malt extract and bring to a boil.
  5. Immediately add hops, cover, and maintain the boil for 60 minutes.
  6. Cool to 68°F. 
  7. Pitch the yeast.
  8. Ferment at 66°F for 1 week. 
  9. Rack to clean jugs for secondary fermentation.
  10. Ferment for 1 more week before bottling.
  11. Mix the dextrose into the beer and bottle.
  12. Age beer for 4 weeks.

Golden Oatmeal Coffee Stout

This all-grain recipe makes 5.5 gallons. The final product should have 5.6 SRM, 4.5% ABV, and 20 IBUs.

Ingredients

  • American – Pale 2-Row – 8 lbs
  • Flaked Oats – 1.5 lbs
  • Belgian – Biscuit – 0.5 lbs
  • American – Carapils – 0.5 lbs
  • American – Caramel / Crystal 15L – 0.5 lbs
  • Rice Hulls – 0.5 lbs
  • Cascade – 1.6 oz
  • Coffee – 2 oz
  • Cocoa Nibs – 1 oz
  • Vanilla Beans – 5

Method

  1. Heat 4 gallons of water to 152°F. Then add to the mash vessel.
  2. Slowly add the fermentables to the mash vessel. Stir while adding.
  3. Mash at 152°F for 1 hour.
  4. Fly sparge at 155°F for 1 hour with 4 gallons. Collect 7 gallons of wort.
  5. Begin the 60-minute boil.
  6. Immediately add the hops.
  7. Cool the wort to the pitching temperature.
  8. Transfer to the primary fermenter.
  9. Pitch yeast.
  10. Ferment starting at 65°F with incremental temperature increases.
  11. Transfer to secondary.
  12. Add the coffee, cocoa nibs, and vanilla beans.
  13. Ferment.
  14. Bottle or keg.