New FT-IR method to control the evolution of the volatile constituents of vinegar during the acetic fermentation process

FT-IR calibrations have been made to estimate the aromatic compounds present in vinegars during the acetic fermentation process. A change in the concentration of the major species takes place in this process; ethanol drops from values of around 12% to <1%, while acetic acid increases from values of <0.02% to >10%. To perform these FT-IR calibrations specific zones of the IR spectrum have been employed, which have permitted the calibrations to be validated, with prediction error values below 10% for ethyl esters and higher alcohols, and with errors below 20% for fatty acids. For the case of derivatives of acetic acid and furfurals, the prediction errors in the validation of the method were between 20% and 30%.