Determination of Fatty Acids in Beer by Fast Routine Analyse

Význam tématu

Rapid quantification of fatty acids in beer is vital because these compounds influence yeast vitality, foam stability, and flavor profile, including off-flavors such as rancid or goaty notes. A fast routine method supports quality control and consistent product characteristics.

Cíle a přehled studie

This study aimed to develop and validate a rapid, routine procedure for simultaneous determination of medium-chain (C4–C10) and long-chain (C12–C18) fatty acids in beer or hopped wort, based on solid-phase extraction (SPE) and fast gas chromatography.

Použitá metodika a instrumentace

• Sample preparation: SPE on LiChrolut EN cartridges conditioned with methanol and water; beer acidified with HCl, spiked with internal standards (heptanoic and pentadecanoic acids), washed, nitrogen-dried, and eluted with chloroform.
• Derivatization: BF3-methanol (14%, v/v) methylation of long-chain acids at 95 °C for 20 min; extraction of methyl esters into hexane.
• GC-FID analysis: DB-WAX capillary column (10 m × 0.18 mm × 0.18 µm), helium carrier at 200 kPa, oven program (120 °C hold 0.7 min, 30 °C/min to 200 °C, hold 6 min), split 1:10, injector and detector at 220 °C, autosampler Labio ASG 40.

Hlavní výsledky a diskuse

• Linearity: Calibration over 0.0015–8 mg/L; correlation coefficients r = 0.9971–0.9999.
• Recovery: 96–107% for medium-chain (avg. 100%), 95–115% for long-chain (avg. 105%).
• Repeatability: RSD 5.8–8.3% for medium-chain, 11–16% for long-chain acids.
• Retention time stability: RSD < 0.11%; peak area RSD < 6.4%.
• Analysis time: less than 4 minutes per run using 0.18 mm ID column, significantly increasing laboratory throughput.

Přínosy a praktické využití metody

The method combines high speed, accuracy, and minimal solvent use, making it suitable for routine brewery QA/QC. It enables simultaneous monitoring of key fatty acids, ensuring consistent beer quality and reducing operational costs.

Budoucí trendy a možnosti využití

• Further miniaturization with narrower or micro-GC columns to reduce analysis time.
• Full automation of SPE and derivatization for higher throughput.
• Coupling with mass spectrometric detection for lower detection limits and structural confirmation.
• Extension to other fermented beverages and raw material profiling.

Závěr

The validated SPE/fast GC-FID approach offers a rapid, reliable, and reproducible route for determining fatty acids in beer, meeting modern demands for efficient quality control in brewing.

Reference

• Hage, T. (1987). Free fatty acids in beer – use of a Binder-phase column for extraction. Proc. Fourth European Conf. Food Chemistry, 106–110.
• Horák, T., Čulík, J., Jurková, M., Čejka, P., Kellner, V., Dvořák, J., Hašková, D. (2009). Faster gas chromatography and its utilization in brewing, part 3 – determination of some low volatile beer flavours. Kvasny Prum., 55, 304–309.
• Baltusen, E., Sandra, P., David, F., Cramers, C. (1999). Stir bar sorptive extraction (SBSE): theory and principles. J. Microcolumn Sep., 11, 737–747.
• Merck (2005). ChromBook 2006/07, 22–23.
• Clarke, B. J., Davine, D. F., Hawthorne, D. B., Kavanagh, T. E., Moulder, P. J. (1981). Factors affecting medium chain fatty acid formation during fermentation. Tech. Q. Master Brew. Assoc. Am., 18, 188–194.