GC/MS-based metabolomics study to investigate between ale and lager beers differential metabolites

The GC/MS-based metabolomics method was done to show differential metabolites between ale and lager beer. The metabolite profiles of ale beers were significantly different from those of lager beers. Ale beers contained significantly higher levels of propylene glycol, 2,3-butanediol, propionic acid, glycerol, succinic acid, malic acid, fructose, sorbitol, palmitic acid, stearic acid, and sucrose, but lower levels of alanine, glycine, leucine, isoleucine, phenylalanine, and tryptophan compared to lager beers. Relatively high correlations were found between stearic acid and palmitic acid (r = 0.98), leucine and isoleucine (r = 0.95), and glycine and alanine (r = 0.91). Alcohol content, hops, and wheat related metabolites were identified, which could affect the metabolic differences be-tween ale and lager beer. A Random Forest approach extracted some key metabolites for beer type prediction with low error rates of 13.5% in the training set and 8.2% in the test set, respectively. This study highlights that GC/MS-based metabolomics is a powerful method for identifying metabolic differences between ale and lager beers.