How to Brew an Imperial Stout Beer | Craft Brewer Tips

Posted by
Mike Benson
on 19/06/23

About Me

Mike is the sales manager for Wales and the West of England and is located in Wigan.

You can read my bio by clicking the button below

It was in the USA that I developed a love, in Belgium that I realized it, and in Germany that I longed for it. Unfortunately, it’s not my wife, kids, and dogs I’m talking about, it’s Imperial Stouts.

I have always had a love for dark beers and always looked forward to brewing them. In my humble opinion, a rich dark stout’s flavor and body are unmatched by any other style. They are refreshing and a fantastic pairing with many foods and desserts.

But who would not choose the Imperial version? Not the actions of an empire or a method, but the majestic meaning. Imperial Stouts allow brewers to create a full-body, full-flavor beer using both standard and modern ingredients. We can play around with pretty much anything: fruits, chocolate, spices, and barrel aging. They are all welcome.

Posted by
Mike Benson
on 19/06/23

About Me

Mike is the sales manager for Wales and the West of England and is located in Wigan.

You can read my bio by clicking the button below

Read Me

The brewhouse where I learned how to brew was exceptional at making stouts. The brew kit was nice, but it was the water that gave us a head start. High in alkalinity (as CaCO3) and had good sodium levels, we would usually treat the HLT with a special acid blend to bring it below 100 ppm (CaCO3) and prevent increased wort pH’s and making beers unstable.

As we all know, some things in the brewery are not too reliable, for us the acid dosing was one of those. Luckily for dark beers, it did not matter too much as they are full of roasted malts which reduce wort pH, making a perfect harmony.

The grist selection for an imperial stout is an open book. It can be a simple 90% base malt and 10% roasted barley or a complex combination of non-malted cereals to improve smoothness and body, crystals to impart color, caramel, vanilla, and dark fruit flavors, and roasted malts to intensify the color and add pastry, coffee, and roasted flavors.

One of the things we need to be careful of is Diastatic Power (DP), as we increase the addition of specialty malts and we dilute the DP so mashing conditions for stouts are usually 63^oC (145.4^oF) for 90 minutes to give maximum activity for a long amount of time. Keep an eye on the pH to make sure you are in the correct range, as we have mentioned, those roasted malts will lower wort pH so you may need to make some adjustments. If you need to raise the pH, Sodium bicarbonate is a good option as it also adds to body. To increase the DP levels choosing an extra pale base malt is a good idea, the lower kilning temperature gives greater enzyme levels. You can also use fungal alpha-amylase or even AMG from your preferred enzyme supplier to ensure you get full conversion.

One thing we can struggle with is getting the original gravity needed for the high alcohol level. If you have an oversized mash tun, you may be able to make an all-malt imperial stout in one go, but more often than not, it’s a double mash, so you are in for a long day. The good news is that sugar additions are more than welcome, and this is another opportunity to enhance the flavors by experimenting with the different sugars available to us. Not all sugars are the same when it comes to fermentation. Dextrose (glucose) is very fermentable and easily utilized by yeasts. Sucrose is not directly fermentable by brewer’s yeast, and the enzyme invertase is needed to separate the glucose and fructose outside the cell so they can be consumed. Lactose is unfermentable and is used heavily in milk stouts, while maltodextrins are nonfermentable but add body and mouthfeel.

Fermentation can be one of the most challenging parts of brewing a high-gravity stout. We are asking the yeast to go above and beyond normal duties, and we need to make sure it has the tools to finish the job. All the extra sugar addition will dilute the Free Amino Nitrogen (FAN), and you will need a supplementary supply of nitrogen and zinc to make up for this. The yeast choice is also a major factor, a strain such as Kveik is nitrogen hungry, so higher additions may be needed. For particularly troublesome fermentations, adding Diammonium Phosphate (DAP) is an option.

Yeast management is key. Higher oxygen levels at the start of fermentation are needed, along with an increase in the pitching rate. An extra boost of oxygen during the lag phase of fermentation will ensure good yeast growth, and skimming dead yeast or removing dirty bottoms will keep the fermentation healthy.

Extra flavors can be added to the boil or fermentation, with the boil being my preference. The final gravity is usually quite high, between 1015 and 1030 (3.75– 7.5 Plato), so any infection from additions poses a significant food safety risk. Once fermented, the yeast settles, and the wine is sent to a foeder or barrel for further aging or to pack. A bottle is my favorite package in this instance; the more drama, the better. A lovely sharing bottle with a crown cork and the wax top is the cherry on top of this amazing beer.

As I write this, I’m sitting enjoying the evening sun with my wife, sipping a Tracing Time from Duration. Even in the warmer months, these beers are sensational.

If you have the urge to brew up one of these beasts, get in touch with one of the team and have a chat about using non-malted cereals and brewing malts in craft stout beer.

Duration Beer image courtesy of Ashley Carter Images

FACEBOOK

TWITTER

Our Malts