Effect of Nutrients and Growth Stimulators on Acetic Acid Fermentation using Natural Consortia

Abstract

Acetic acid bacteria comprise a group of Gram negative, rod-shaped with aerobic metabolism using oxygen. From the natural inoculum, bacteria were isolated and characterized. Two main genera were determined as Acetobacter and Gluconobacter. Optimization of concentrations of alcohol, nitrogen source, phosphate source and magnesium sulphate was carried out by applying central composite design (CCD) of RSM for preparation of apple cider vinegar. Apple wine and cider vinegar was prepared by using optimized conditions from response surface methodology (RSM) experiment. Acetic acid fermentations were carried out with different cultures and growth regulators. The treatment having maximum titratable acidity (5.07%) was achieved in run number 2 having 5% initial alcohol concentration, 0.5% K2HPO4 and 0.25% ammonium sulphate with natural consortia. It was found that the maximum acidity of 4.56% was achieved in run number 23 having 5% alcohol concentration, 1.25% yeast extract, 0.25% NH2HPO4 and 0.55% MgSO4 with natural consortia. It is concluded that to have optimum acetic acid production for cider vinegar production, the optimized concentration of nutrients and growth regulators was suitable, using natural consortia in the form of pellicle.