Strict control of diacetyl levels is a crucial aspect of making high quality lagers. Tools like PLAATO Pro can be used to get real-time insights and improve timing of diacetyl rest and consistency in flavor.

Diacetyl is a naturally occurring flavor compound created in the early phases of fermentation processes. It is typically associated with buttery popcorn and can contribute to a unique profile in a Pilsner style beer. Most brewers prefer a low level of diacetyl to create a balanced and crisp beer.

Controlling the level of diacetyl was typically achieved by lagering the beer for months, but much similar results are achieved at a fraction of the time by simply raising the temperature at the end of fermentation. Lagers will typically ferment at 10-14C (50-60F) during primary fermentation, and is raised to 18-20C (60-70F) when the gravity is 2-3P from the target FG, efficiently reducing the level of diacetyl in a matter of days.

Resting before it’s too late

If the beer is allowed to fully consume its fermentable sugars in the fermentation process without raising the temperature prior to this point, temperature changes have less effect on the reduction of diacetyl, and the “window” for diacetyl rest is closed.

Get notified when it is time to rest

This is where real-time fermentation monitoring systems like the PLAATO Pro come in handy. Add an alert in the PLAATO Pro app that will notify you once the desired SG is reached. This means you can achieve a higher level of repeatability by being more concise in events like a diacetyl rest.

This feature also allows you to tune the level of diacetyl to your preference. By accurately controlling the parameters of the diacetyl rest, including the SG at which the diacetyl rest should begin, you can experiment your way to the perfect taste profile.

Understanding your fermentation profiles and when to diacetyl rest

F

The graph shows three different lager fermentation profiles from three different batches, using PLAATO’s batch comparison feature to overlay the data. As seen, the chosen point of diacetyl rest (1.020 SG / 5 °P) varies with two days in between the batches. The parameters affecting when a fermentation process reaches a certain point is vast, and typically includes yeast– strain, vitality, pitching parameters, temperature, recipe and many other factors.

How does PLAATO Pro work?

PLAATO Pro connects to your fermenter with a 1.5” tri-clamp and sends real-time gravity and temperature insights to your smartphone through the PLAATO Cloud.

The Pro is a plug-and-play, Wi-Fi-connected sensor that analyzes fermentation progress in real-time, measuring the key parameters: density and temperature. Installation usually only takes a few minutes. Fermentation readings are taken around the clock and sent to your device through the PLAATO Cloud, where insights can be accessed by all brewery members across your devices.