Ethyl acetate adds to complexity at lower concentrations, and is not considered to spoil a wine until levels become detectable (around 100–125 mg/l) (Francis and Newton, 2005). It is produced by yeast and bacterial metabolism, as well as through the chemical esterification of ethanol and acetic acid during wine aging. Acetic acid is formed by most yeast species during fermentation, but some strains produce more than others (Swiegers et al., 2005). It has a sour, vinegary taste and aroma and is the major component of volatile acidity.