Determination of free fatty acids in beer wort

The importance of free fatty acids (FFAs) in wort has been known for a long time because of their influence on beer quality and yeast metabolism. Lipids have a beneficial effect on yeast growth during fermentation as well as negative effects on beer quality. Lipids content of beer affects the ability to form a stable head of foam and plays an important role in beer staling. Moreover, the ratio of unsaturated and saturated fatty acids seems to be related to gushing problems. A novel, simple, and reliable procedure for quantitative analysis of FFAs in wort was developed and validated. The determination of FFAs in wort was achieved via liquid–liquid cartridge extraction, purification of FFA fraction by solid phase extraction, boron trifluoride in methanol methylation, and injection into GC-FID system. The proposed method has high accuracy (<0.3%, expressed as the bias), high precision (<1.2%, RSD), and recoveries ranging from 74% to 98%. The method was tested on two different wort samples (9° and 12° Plato).