Influence of fermentation temperature on semi-continuous acetification for wine vinegar production

This paper describes semi-continuous acetic acid fermentations for wine vinegar production performed isothermally and using temperature gradients in order to determine the influence of temperature on this industrial biotransformation. Acetifications were conduced in 6- to 100-l reactors. Overall process productivity improved about 15–20% using a temperature gradient. An initial temperature of 32 °C was employed until the product concentration reached 90–95 g/l/h. Thereafter, the temperature was gradually reduced to 30 °C until the end of the production cycle. Under these operating conditions, the 100-l acetator yielded an overall productivity of 1.84±0.03 g/l/h, a maximum acetification rate of 2.10±0.02 g/l/h, a 94.3±0.4% process yield, and a final acetic acid concentration of 116.0±0.9 g/l.