Determination of the fermentable extract in beer and wort
This method is suitable for all types of beer and wort.
Beer or wort is fully attenuated under agitation in an Erlenmeyer flask after yeast has been added. From the difference between the extract content prior to fermentation commencing (original gravity) and after fermentation is complete, the limit of attenuation is calculated.
Real extract minus apparent extract of the fully attenuated beer (from which the alcohol was removed) yields the value for “apparent attenuation”, because during the final stages of attenuation alcohol is produced.
The portion, which has actually been fermented, can be calculated through multiplication by the factor 0.81. This factor is related to the so-called attenuation quotient q [1].