One of the most common questions for beginner brewers is when it comes to ending fermentation. When do we conclude that the beer has finished fermentation and has it been fermented properly?

The end of the first fermentation is the stage in which the sugar level, measured with a hydrometer, stops falling. The average period of measurements is 48 hours. So we measure the density, e.g. on Monday we save the reading and compare it with the reading made on Wednesday. If the indicated Plato/BLG value on the hydrometer has not changed, we assume that the first fermentation is complete. However, questions arise very often, what should this Plato/BLG value be at the end of beer fermentation? Should it drop to zero or should it be higher and what does it mean in practice?
There is no accepted single Plato/BLG value that would mark the end of fermentation.
The amount of sugar in young beer after fermentation depends on many factors.
Initial density of the wort. The more sugars in the wort before the yeast treatment, the greater the amount after fermentation. A wort with a starting value of 16 Plato/BLG will not attenuate as much as a wort with a value of 11 Plato/BLG. Typically, this thicker wort will have more residual sugars after fermentation than the weaker wort. For a stronger setting, under the same fermentation conditions, the difference may be from one to several degrees of Plato/BLG.
The type of yeast used. Not every yeast strain works the same. We have strains that ferment deeply and strains that do shallow fermentation, leaving more residual sugars. The same wort fermented with different yeasts can complete the fermentation at a different level.
The amount and condition of yeast. A very important factor is the right amount of live yeast cells that we will use to ferment the beer. In short, if we use dry yeast, usually one sachet is designed for 20-25l of beer with a density of up to 13 Plato/blg. For larger amounts of beer or higher density than 14 Plato/Blg, it is a good idea to add two sachets. Too low amount of live yeast cells will result in slow fermentation, which will make it difficult to correctly assess its completion.
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In conclusion, there is no single constant BLG value that marks the end of fermentation. The most important for the evaluation of the end of fermentation is the fact that the process of lowering the amount of sugar in young beer has stopped. The adopted range of attenuation for beers with a density of 11-13 Plato/BLG is 0 - 4.5 Plato/Blg. Should the final value in our opinion be too high, fermentation can be induced by adding another yeast strain with a similar flavor profile, but with a deeper fermentation.
If you have a problem with the selection of the appropriate yeast, please contact us: sklep@twojbrowar.pl