The evolution of sugars and of wort density during beer fermentation

Are you able to clearly determine the end of fermentation of your beer?

Do you know how to avoid the problems created by an incorrect beer priming?

To answer these questions, researchers of the CDR chemical lab “Francesco Bonicolini” conducted a study on brewing with the aim of:

• understanding which is the best method to determine the end of the fermentation process;
• determining the residual sugar concentration in order to avoid problems in the priming phase.

For this purpose we studied the evolution of fermentable sugars as well as the variation of wort density during fermentation.

Below you will find:

In order to carry out this study two different beer worts were produced in the laboratory, both following a recipe for IPA beers, except for the yeast type. In fact, a low attenuation yeast was added to the wort in one beer, while a high attenuation yeast was used in the other.

CDR BeerLab® was used to determine the change in concentration of fermentable sugars, while a portable digital densimeter was used to measure the variation in density of the wort.

Data was collected thanks to these two tools from the yeast inoculation until the time in which fermentation was said to be ended.

It is possible to evaluate the trend in concentration of fermentable sugars present in the beer wort from the results of the analysis performed.

As the results suggest, the first sugars to be fermented by the yeasts are glucose, fructose and sucrose. In fact, for both worts, these three sugars are almost absent after four days. Also maltose and maltotriose (determined together with maltose) are fermented but at a later stage.

Fermentation can be considered completed after 6 days, when the concentration of sugars remains constant in 2 measurements performed at a distance of 24 hours.

It can be noted that the concentration of residual sugars is different in the two beers produced due to the characteristics of the different yeasts used.

This difference is to be kept in mind when assessing the end of fermentation, which does not always end when the residual concentration of sugars is close to zero.

It is also important to know the residual concentration of sugars at the end of fermentation in order to correctly evaluate the amount of sugar to be added to the beer in the priming phase in order to avoid over-gassing.

From the results of the analysis performed, we note that the portable digital densimeter is quite accurate in assessing the density of the wort, thus it can be used to control the progress of the fermentation process. Instead, the use of CDR BeerLab® is to be favored to establish the effective end of fermentation, since it is more precise and capable of detecting even the slightest changes in sugar concentration that the portable densimeter is not capable of highlighting as effectively.

Having the safety of having completed the fermentation is essential for the priming phase.

To avoid over-gassing, which could give rise to gushing, it is essential to be sure that the fermentation is complete. The analysis of fermentable sugars is therefore of primary importance for the calculation of the amount of sugar to be added in the priming phase, thus obtaining the volumes of CO2  required from the recipe adopted.

We can state that fermentation is concluded when the concentration of sugars remains constant for 24 consecutive hours. Therefore, to determine the end of the fermentation process, it is much more effective to control the variation in concentration of sugars in the wort rather than the density.

CDR BeerLab® is considered the most suitable tool to determine the end of fermentation, being able to detect even the slightest variations in concentration of sugars that otherwise, i.e. by measuring the density, would not be able to be appreciated.

With CDR BeerLab® it is possible to measure the exact concentration of residual sugars at the end of fermentation in order to avoid errors in the priming phase.