Quantitation of Vitamin B6 Vitamers and Glycosides in German Alcohol-Free and Full-Strength Beer by a Stable Isotope Dilution LC-MS/MS Method.

Vitamin B6 is an essential cofactor of numerous enzymes, and beer may contribute substantially to its dietary intake. While vitamin B6 occurs predominantly as glycosides in plants, data on the complete vitamer profile in beer remain scarce. Here, a novel SIDA LC-MS/MS method was developed for the native quantification of pyridoxine, pyridoxal, pyridoxamine, 4-pyridoxic acid, pyridoxine-5'-β-glucoside, pyridoxine-5'-β-maltoside, and pyridoxine-5-β-cellobioside. The method was validated for linearity, precision, recovery, and limits of quantification (0.20-12.9 μg/L) and detection. Analysis of 65 beers revealed total vitamin B6 concentrations ranging from 95.3 to 1020 μg/L, including multiple B6 glycosides. Variations in vitamin B6 composition were primarily associated with raw materials rather than with brewing technology. No significant differences were observed between alcohol-free and corresponding full-strength beers, whereas wheat beers showed vitamin B6 contents significantly lower than those of lager beers. Bock beer exhibited the highest concentrations. This study provides a comprehensive analytical basis for future investigations of vitamin B6 during brewing.