Whether it’s milk, barrel-aged, imperial, nitro or pastry; let Alix Blease at Lallemand guide you through the stout brewing process as we head into shorter days.

No one will disagree that we have had a fantastic summer, the weather has been warm, the beer has been flowing and the outdoor taprooms have been bustling. But as the days get shorter, and the taproom benches get brought inside, signifying the end of summer, it’s time to consider your recipe for this year’s big stout. 

Stouts with a high ABV and high adjunct content will push your equipment and yeast to its limits, so there are some considerations you need to make before diving head first into the brew day.

Stressed yeast leads to off-flavours and extended fermentation times. If a large proportion of the grain bill is made up of adjuncts, or you are considering adding lactose, then this can lead to the creation of a wort with a lower fermentability as well as lower level of FAN (Free Amino Nitrogen). Loading up your mash tun with a heavy dose of roasted malts can also make your  beer harsh and unbalanced.

Choosing a base malt which brings a nice, toasted flavour, but with plenty of fermentable extract such as Maris, Vienna or Munich is ideal. Layering some crystal malts to add sweetness and body, will help balance out any bitterness. Including some oats, wheat or dextrin will help enhance mouthfeel.

If your mash tun is already creaking under the weight of a massive grain bill, then try adding 50-60g/hl of ISYEnhance into the whirlpool or at the end of the boil to achieve a similar effect of increasing the mouthfeel and body in the final beer without any additional kg of grain. 

Water chemistry is always important in brewing and stouts are no different. A ratio of 1:3 sulphate:chloride is a good target to aim for in stouts and darker beers. These increased chloride levels enhance smoothness, malt flavour, and sweetness. If you are concerned about the acidity of the roasted grains you have added, then you could consider using bicarbonate as a buffer.

Aiming to get into that higher duty bracket with over 8.5% ABV? Then your yeast choice can make or break it. There are three fermentable sugars in wort; glucose, maltose and maltotriose. Not all yeasts ferment all sugars. Windsor for example is maltotriose-negative, and LoNa only ferments glucose. Even between the maltotriose positive yeasts there is still variation in the affinity of the strain to metabolise maltotriose.

Stouts with a high ABV and high adjunct content will push your equipment and yeast to its limits, so there are some considerations you need to make before diving head first into the brew day.

Alix Blease, Lallemand

Opting for a strain with high maltotriose utilisation such as LalBrew Nottingham or LalBrew Verdant will mean that you can achieve the higher abv’s with less bother. Make sure that you are pitching plenty of yeast (maybe even more than the pitching rate on the TDS) to handle the higher gravity, there needs to be plenty of yeast cells to create all that alcohol!

In addition to selecting the correct yeast strain for the job you need to support it as well. Oxygen and nutrients are key here. For very high gravity worts oxygenating the wort on transfer and again on day 1 helps yeast replicate, meaning plenty of cells for fermentation. If there is not enough biomass then you could end up with your fermentation stalling or the production of off-flavours.

Stalling and off-flavours can also be avoided with the correct yeast nutrition. Adjunct heavy grain bills means that there is less FAN and zinc available to the yeast. Zinc is an essential trace element that is typically taken up rapidly by yeast early in fermentation.

It contributes to protein synthesis and yeast growth, protects enzymes, stabilizes the protein and membrane systems, and accelerates maltose and maltotriose uptake, which in turn can provide faster fermentations, and better flocculation and attenuation.

YeastLife Extra provides all-around nutrition, including zinc and FAN, to ensure healthy yeast cells at each generation, minimising off-flavours and speeding up fermentation. For really imperial stouts, consider adding Servomyces alongside Yeastlife Extra. You could even add a smaller dose of nutrient mid-fermentation to help out the next generation of yeast.

As the yeast make their way through the sugars there is going to be a longer fermentation and more generations of yeast produced. This will lead to a higher proportion of dead yeast accumulating in the bottom of your fermentation vessel. Knock off a small volume of yeast from the bottom of the fermenter every day to prevent autolysis flavours and keep yeast healthy.

To avoid higher alcohol flavours in the final beer it is recommended that you ferment at a steady rate between 18-20 degrees. If you need to reduce tank residency time, then adding ALDC cuts maturation time by avoiding diacetyl production. As the yeast will have worked very hard during fermentation to create this beautiful stout, avoid reusing yeast from this batch as it’s probably pretty worn out already.

So as the nights draw in and roasted grains make the first runnings darker, remember: if you’re going to spend the season indoors, you might as well do it with a stout worth sipping.