Emissions of Volatile Organic Compounds during Acetic Acid Fermentation in Vinegar Industry

Abstract

Gas emissions occurring during acetic acid fermentation were studied. Ethanol, acetic acid and ethyl acetate are the main components of the exhaust gases. The volatilities of these compounds have been measured to study their evaporation. VOC emissions were quantified for fementation cycles producing vinegars with different final acetic acid 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 clearly that these atmospheric losses are responsible of a decrease in the ethanol/acetic acid conversion yield. The losses depend on the ethanol and acetic acid concentrations in the fermentation medium, and represent up to 2.1% of the final acetic acid theoretically produced. Residual ethanol concentration, absolutely necessary to maintain cell viabilitity, contributes also to the conversion yield decrease.