Limited growth of the background microbiota was observed during the short Enterobacteriaceae stage, with an indicative absence of both short-and branched-chain fatty acids. Most metabolites observed during the main fermentation stage were yeast-associated metabolites including ethanol, methyl-1butanol and succinic acid. The production of ethyl acetate and ethyl lactate, the most abundant esters in lambic beer, coincided with the beginning of the main fermentation stage at week 3, with maximum concentrations measured during the final maturation stage. Acetoin levels corresponded with the presence and growth of AAB, with production starting and then increasing from 7 weeks to 6 months before dropping, coinciding with lower AAB cell count, likely due to consumption of acetoin by yeast cells. Acetic acid followed a similar trend to acetoin, with production beginning from week 7 and increasing along with the increase in AAB. However, acetic acid was not consumed and even increased during the acidification and maturation stages, likely due to the presence of Brettanomyces species, P. damnosus, and P. membranifaciens. Both D-and L-lactic acids were produced in near equal concentrations, reaching a maximum in the acidification and maturation stages. The depletion of malic acid coincided with increases in lactic acid bacteria (LAB), consistent with malolactic fermentation, which had not been previously reported for lambic fermentations. Biogenic amines are potentially dangerous when present in high concentrations , and are typically produced by enterobacteria in the Enterobacteriaceae stage of lambic beer production .