Free Amino Nitrogen in Beer - UV Vis Spectroscopy

In this application, beer is mixed with a color reagent, boiled, and the resulting color is measured spectrophotometrically to determine the free amino nitrogen (FAN) present. For full sample, method, and results information, proceed to download the application note below.

Why is Free Amino Nitrogen Content in Beer Important?

The sum of the bioavailable nitrogen components in the wort is represented by the free amino nitrogen (FAN). Especially the concentration and composition of amino acids do matter for the flavor profile of beer. An excessive FAN content can lead to difficulties during the yeast fermentation, resulting in bad taste and in microbial instability of the beer. FAN levels are also a good indicator of when fermentation is complete. 

How is Free Amino Nitrogen Measured Spectrophotometrically?

In this application, the prepared beer is mixed with a color reagent (based on ninhydrin), boiled and the resulting color is measured using the UV7 Excellence Spectrophotometer. The produced color intensity depends on the various amino acids available. Amino acids, ammonia und the terminal alpha-amino-groups of peptides and proteins are taken into account and the FAN content is determined.

While the application note and the method were developed using a UV/VIS Excellence spectrophotometer, the method described in the application note can also be adapted in EasyPlus UV/VIS spectrophotometers.