Magnesium-Accelerated Maillard Reactions Drive Differences in Adjunct and All-Malt Brewing

Magnesium impacts key processes in brewing including yeast metabolism and mash pH but is typically overshadowed in brewing studies, owing to the established centrality of calcium. Using flame atomic absorption spectroscopy (FAAS), a 33.7% average increase in magnesium concentration in commercially available beers brewed with 100% barley malt versus those brewed with adjunct grains was identified. Parallel analysis of brewing grains implicates rice in driving this discrepancy. Given the known catalytic properties of magnesium, its role in beer color development via Maillard chemistry using model systems and wort (unfermented beer) was investigated. Kinetic data were obtained by ultraviolet-visible spectrometry and reaction species were identified by electrospray ionization mass spectrometry. Magnesium accelerated Maillard chemistry in all systems in a dose-dependent manner. These findings reveal a divergence in outcomes of all-malt and adjunct brewing driven by magnesium-catalyzed color formation in the brewhouse. It is proposed that magnesium inhibits water mobility and serves as a Lewis acid catalyst to facilitate Maillard reactions.