Effect of Vinegar Components on Growth of the Contaminant Gluconacetobacter xylinus in Vinegar

Abstract

Gluconacetobacter xylinus is transmitted by the fly which belongs to the genus Drosophila and grows without agitation in vinegar. In private households, a serious problem that a thick cellulose pellicle is formed frequently happens with vinegar. Therefore, we investigated to design the rice vinegar which has difficulty in growth of thick pellicle forming G. xylinus. On commercial products (rice vinegar in Japan) contained 4.2–4.6% acetic acid, the pellicle formation was observed at 24℃ in 6–9 days at a inoculum size of about 10³cfu/ml. When the model medium containing ethanol, acetic acid, glucose, gluconic acid, yeast extract and polypeptone was used as a model of rice vinegar, the deletion of ethanol and a high concentration of glucose resulted in an increase of the lag phase. To apply this method to rice vinegar, the active carbon treatment was effective because of the deletion of nutrient from the degradation products of rice. In active carbon treated rice vinegar containing 4.4% acetic acid, 10.1% glucose and 0.30% gluconic acid (0% ethanol), and 2.8% acetic acid, 9.7% glucose and 5.2% gluconic acid (0% ethanol), the pellicle formation was observed in 14 days and 9 days, respectively, and satisfactory result was obtained as a prototype rice vinegar. The latter rice vinegar is very mild, and it is expected as a new type of vinegar.