Optimization and Production of Brewed Vinegar in an Indigenous Packed Bed Fermenter

Brewed vinegar is a product of alcoholic and subsequent acetic acid fermentations of sugary substrates. The present study standardizes initial acidity levels and charging rate of mother vinegar-ethanol for the production of vinegar by adsorbed cells of Acetobacter aceti AC1 in an indigenous packed bed vinegar bioreactor. The fermentation of sugarcane juice carried out with Saccharomyces cerevisiae KY069279 produced 6.67% (v/v) ethanol in 72 h. Acetobacter cells adsorbed on wood shavings with a relative adsorption rate of 88.5% were used as inoculum for packed bed fermentation. The effect of initial acidity studied between 1% to 2.5% (w/v) provided 2% (w/v) as optimum with maximum acetification rate of 6.97 g/L/day. The charging rate of 250 ml/h was optimum with final acidity and acetification rate of 7.1% (w/v) and 13.81 g/L/day in 3.33 days of fermentation. Sequential packed bed fermentation cycles carried out at 15L working volume with different substrates revealed an average final acidity of 6.97% (w/v) with fermentation efficiency of 95.4% obtained in 10 days.