Profiling Free Fatty Acids in Beer Wort Using an Isolator Column-assisted LC-MS/MS Technique

Free fatty acids (FFAs) are integral components throughout the entire malting and brewing process, derived predominantly from various grains. These fatty acids significantly influence the quality of malt, wort, and beer in multiple ways, particularly during fermentation. Therefore, accurate determination of FFA levels, especially in wort, is crucial. To address this need, a method combining liquid chromatography (LC) with tandem mass spectrometry (MS/MS) was developed to determine medium and long-chain FFAs.

The sample treatment involved solid phase extraction (SPE). One of the significant challenges in analyzing FFAs via LC-MS/MS is the interference caused by background signals. This issue was effectively addressed by incorporating an additional isolator column between the solvent pumps and the injection system. This isolator column retained interfering substances from the system, thereby significantly reducing background noise and improving the accuracy of the analysis.

The newly developed method demonstrated comparable results to the conventional method, with no statistically significant differences observed except for oleic acid (C18:1). Moreover, this method proved to be less labor-intensive, faster, more robust, and environmentally friendly.

In addition to these advantages, the method underwent thorough validation and was rigorously tested for robustness and accuracy, ensuring reliable performance under various conditions.

Subsequently, this method was applied to wort samples collected from 20 different German breweries to investigate flavor instability in lager beer. While no clear correlation was found between FFA levels in wort and aging compounds in beer, the method still provides valuable insights into this phenomenon. Future research will focus on applying this method to different brewing-relevant matrices and exploring the complex interactions between these matrices and FFAs, aiming to gain a deeper understanding of their roles in the brewing process.