In a 2018 study, De Roos, et al. investigated the production of metabolites during lambic beer production, identifying metabolites from both yeasts and bacteria associated with the different stages of fermentation and maturation. The authors followed two lambic beer production processes from a traditional lambic brewery located in the Senne river valley over a period of 24 months. The fermentations were carried out with the same wort, which had been manually acidified by the addition of lactic acid prior to being transferred to two identical 660 L oak casks. Several methods were used to measure the different metabolites present, including HPLC coupled with either refractive index detection for measuring ethanol and short chain fatty acid concentrations, or ultraviolet detection for lactic acid stereoisomers. Volatile compound concentrations were measured using GC coupled with flame ionisation detection, while ultra-performance LC (UPLC) coupled with tandem mass spectrometry (MS/MS) was used to determine organic acid and biogenic amine concentrations.