Upscaled Production of Sugarcane Vinegar by Adsorbed Cells of Acetobacter aceti Under Semi-Continuous Fermentation Conditions

Natural vinegar is a food supplement, tonic and nutraceutical produced by twin fermentation of sugar to acetic acid via ethanol. The fermentation of sugarcane juice carried out with Saccharomyces cerevisiae MTCC 11815 produced 9.11 % (v/v) of ethanol with a fermentation efficiency of 89.8 % in 72 h. Statistical optimization of acetic acid fermentation revealed that immobilized cells of Acetobacter aceti (grown in 2 g/L DAHP supplemented jaggery solution) adsorbed on 15-mm-sized Melona grandis wood shavings for 15 h had the highest adsorption rate (66.6 %) followed by Tectona grandis (44.4 %) and Castania sativa (21.4 %) with maximum viable count of 12.76 × 107 and 6.0 × 107 cfu/g in absence or presence of substrate, respectively. A 1L plastic fermenter packed up to half of its length produced sugarcane vinegar with 5.0 % (w/v) volatile acidity in 6 days. These optimized conditions scaled to 5 L in PVC column reactors and 50 L plastic fermenter produced 7.0 % (w/v) and 4.0 % (w/v) volatile acidity in 6–7 days and 7–10 days, respectively. The sugarcane vinegar had a mean sensory score of 8.61 ± 0.52 in comparison to commercial brands with sensory scores of 7.22 ± 0.76 and 7.47 ± 1.02.