When the forest fruits went into the kettle, the wort turned deep red. A little later, the peanut butter powder followed. Not the fatty smell of a peanut butter sandwich, but something closer to Snickers. Mitchell and Jelle looked at the small kettle as if they were brewing, calculating and doubting all at once.
This is Pro Goes Homebrew. A Kegland story series in which we challenge pro brewers to brew a beer on a small kettle. How do they work? What happens when routine and scale fall away? And what can we, as homebrewers, learn from their craft, curiosity and experience?
How seriously can you take a ridiculous recipe?
Peanut Butter Jelly Sour sounds like a beer you mainly come up with to challenge someone. Which, partly, is exactly the point of this series. @ivanabrewing from Croatia shared a recipe with us for a Peanut Butter Jelly Sour. Inspired by the massive hit from the United States by Duncan’s Brewing Company and now familiar to many BrewTubers.
Peanut butter powder. Forest fruits. Lactose. Caramel malt. Oats. A sour yeast. Everything about this recipe says: this could be funny, but it could also go completely off the rails.
Mitchell and Jelle did not treat it as a joke and took on the challenge with real enthusiasm. That was immediately the beautiful thing about the brew day at Troost. There was no professional installation running, no 2,500-litre batch, no tight production schedule everything had to fit into. Just a small kettle on the floor and two brewers slowly turning it into their own test setup. Which, by the way, they do more often, because while the BrewZilla was being filled with water, a Speidel with 50 litres of Baby Witbier was boiling in the same room.
Mitchell and Jelle looked at the recipe, calculated and adjusted. They figured out the BrewZilla’s little control panel and turned the heating element down to 25 percent power, because otherwise the system would overshoot too aggressively. At Troost, they like controlled brewing. First see whether you can keep the temperature stable, then continue.
That may be the core of how they brew. Not because everything has to be complicated, but because they want to understand what is happening.
“If you know how it works, you can anticipate something that happens. If everything is fully automatic, you don’t know what to do when something needs to be adjusted.” — Jelle
Recipe: Peanut Butter Jelly Sour
A 5.8% mixed-fermentation sour beer, brewed on the BrewZilla 35L Gen4 using the no-sparge method.
- Batch size: 19 litres
- SG: 1.059
- FG: 1.015
- Colour: 10 EBC
- IBU: 14
- Boil time: 45 minutes
- Mash water: 27.65 litres
- Sparge water: 0 litres
- Grain bill: 3 kg Pale Ale 2-Row, 1 kg oats and 1 kg wheat
- Hops: 10 g Magnum, 30 minutes
- Flavourings: 300 g peanut butter powder in the final 10 minutes of the boil and 2.25 kg forest fruits at flameout
- Mash schedule: 67°C for 45 minutes, then mash-out at 75°C
- Yeast: 2 packets of Lallemand Philly Sour
- Fermentation profile: 18°C primary, then diacetyl rest, cold crash and kegging/conditioning
Measuring is knowing. But what exactly are you measuring?
The malt went in. They stirred. They watched whether the temperature stayed around 67 degrees. They discussed circulation, pump, filter bed and measurement delay.
Because the BrewZilla thermometer sits at the bottom, close to the element, the measured temperature is not always what is happening throughout the whole grain bed. Mitchell pointed that out pretty quickly. But in brewing, measuring is never just reading a number. It is interpretation. Where are you measuring? What are you actually measuring? How quickly does the system respond? How much trust do you have in the device? And when should you simply stir?
A little later in the mash, the efficiency turned out lower than hoped. The SG stayed around 1.039. That is when the brewer’s brain starts turning immediately. Was it because they did not stir? The malt? The oat flakes? The short mash? Should sugar be added? Lactose? Do you leave it as it is, because a slightly lighter sour may actually become more drinkable?
“It’s version one. It can always improve.” - Jelle
When the forest fruits went in, the beer suddenly became visible. Deep red. Almost Club Tropicana, they joked. The fruit was not simply thrown into the kettle. First purée it. More surface area. More flavour. More sugars available. At the same time, the pulp had to stay out of the process later. That is where craft lives too. Not in following the recipe, but in understanding what an ingredient is going to do.
And then came the peanut butter. Not from a jar, but as powder. It dissolved easily into the wort. We expected the smell of a peanut butter sandwich, but it became more like the aroma of a delicious Snickers. Promising.
A wild idea needs structure
At Troost, much of the conversation was about balance. Not only in flavour, but especially in the process. A sour can be dry and sharp, like a geuze. But a Peanut Butter Jelly Sour may need a little sweetness precisely so it does not become thin and acidic. Peanut butter needs fruit. Sourness needs body. A wild idea needs structure.
Meanwhile, the equipment kept coming up too. The BrewZilla received both praise and criticism. The notches for lifting the malt pipe are clever. The tap is useful. The ability to control power helps. At the same time, the thermometer is not in an ideal place. And the question remains: how do you get the filter bed truly stable?
Fortunately, this was not a simple demonstration. It was a brew day and a conversation about brewing beer with professional brewers. And even with an unusual recipe, Mitchell and Jelle took it seriously. They see a limitation and look for a workaround. They smell peanut butter and think about balance. They see red fruit and think about pulp, fermentation and infection risk. They see a small kettle and ask themselves: how do we get better beer out of this?
Jelle and Mitchell both said this experiment brought them back to the nostalgia of homebrewing. The small amounts of malt. Holding a bag. Stirring. Standing together over a kettle. Jelle called it the pleasant, cosy feeling of “just making something yourself”. At the same time, they did not romanticise it. The quaintness was fun, but it never became mere messing around. They calculated, tested, tasted and corrected. Keep having fun, but do not become blind to what is technically happening. Fortunately, because the result mattered too.
Two weeks later we got together to taste the sour. Transferred into a pressure keg and loaded with plenty of fizz, it was time to pour. The result: a bright red beer with a pale pink head. Peanut butter jelly. A little ridiculous, a little brilliant. And above all: taken seriously.
🎓 Five tips from Mitchell and Jelle
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First learn how your system responds
A small kettle is not a black box. Jelle and Mitchell did not just want to know which button was where, but especially what the system did when you changed something. How hard does the element heat? What does the pump do to the filter bed? How does the temperature respond? If you understand how your system works, you can adjust as soon as something runs differently than planned.
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Do not just measure. Understand what your measurement means
A temperature on your display is only useful if you know where and how it is being measured. Especially on small systems, there can be a difference between what the sensor shows and what is happening in your mash. For Mitchell and Jelle, measuring is therefore not about blindly trusting a number, but about interpretation: does this match what I see, smell and expect?
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Steer your process, not just your recipe
The recipe aimed for 1.059, but the wort came out much lower. For Mitchell and Jelle, that was not a mystery, but information. The oats were not ordered crushed, the system behaved differently from their own installation and the efficiency was disappointing. A recipe is not a guarantee. You have to keep watching what is really happening in your kettle and understand where deviations may come from.
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Take strange ingredients seriously
Peanut butter powder and forest fruits may sound like a joke, but in the glass it was all about balance. The peanut was not dominant, but gave a subtle nutty undertone. The fruit stayed recognisable, the beer became dry and the sourness did not pull everything out of shape. Especially with odd ingredients, you have to keep tasting seriously: what is this really doing to the beer?
