CONTINUOUS VINEGAR PRODUCTION USING TWIN BIOREACTORS MADE FROM ETHANOL FERMENTER AND ACETIC-ACID FERMENTER - STUDIES ON ACETIC-ACID FERMENTATION

A new type bioreactor system was developed for continuous vinegar production. Twin bloreactors were assembled from an ethanol fermentor (3 l-working volume) and an acetic acid fermentor (2 l-working volume) in which Saccharomycodes ludwigii and Acetobacter aceti were predominated, respectively. Both organisms were used as cell suspensions in each fermentor. Optimized conditions for continuous vinegar production were examined with saccharified rice bran medium containing 10% glucose and 1% acetic acid. Rice vinegar containing 6.1 to 6.5% acetic acid was produced at the total residence time of two fermentors of 25.6 to 38.9 h and the acetic acid productivity was 3.5 to 5.0 g/(l . h), when the medium was allowed to flow through the bioreactors at 128 to 195 ml/h. The functions of the bioreactors were maintained constant after a successive use for 55 days. Several advantages with such twin bioreactors for continuous vinegar production were also discussed.