Profiling of free fatty acids in wort using an isolator column-assisted LC-MS/MS approach

Free fatty acids (FFA) play a crucial role from the entire malting to the brewing process. They derive predominantly from different grains and affect malt, wort and beer quality in various ways, especially during fermentation. An accurate determination of FFA is fundamental in these matrices, especially wort. Therefore, a liquid chromatography (LC) coupled to a tandem mass spectrometer (MS/MS) method was developed for the determination of medium and long chain FFA. Sample treatment was achieved by solid phase extraction (SPE). The use of an isolator column reduced the system-derived background significantly. The method showed comparable results towards the conventional method with no statistically significant differences except for oleic acid (C18:1). At the same time, it was less labor-intense and therefore prone to error, faster, and more environmentally friendly. Finally, the method was applied on a sample set of 20 different German breweries to investigate flavor instability of lager beer. While there was no clear correlation between FFA in wort and aging compounds in beer, the method can still give valuable insights into this phenomenon. Future research will focus on the application of the method on different brewing-relevant matrices and the complex interactions of these matrices and FFA.