Emissions of volatile organic compounds during acetic acid fermentation invinegar industry

Gas emissions occurring during acetic acid fermentation were studied. Ethan ol acetic acid and ethyl acetate are the main components of the exhaust gas es. The volatilities of these compounds have been measured to study their e vaporation. VOC emissions were quantified for fementation cycles producing vinegars with different final acetic add concentrations. They can reach 16. 5 g m(-3) h(-1) at the beginning of the production of a vinegar containing 140 g l(-1) final acetic acid. The present results show dearly that these a tmospheric losses are responsible of a decrease in the ethanol/acetic acid conversion yield. The losses depend on the ethanol and acetic acid concentr ations in the fermentation medium, and represent up to 2.1% of the final ac etic acid theoretically produced. Residual ethanol concentration, absolutel y necessary to maintain cell viabilitity, contributes also to the conversio n yield decrease.