In this study, we developed vinegar depending on the quantity consumed and type of peeled and unpeeled roots of Platycodon grandiflorum (PG) using Acetobacter pasteurianus A11-2, analyzed vinegar samples using colorimeter and HPLC for 15 days to assess the characteristics on quality, and evaluated their antioxidant activity using 1,1-diphenyl-2-picry1 hydrazy1 (DPPH) and 2.2’-azinobis-(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical scavenging activities. The major result in PG vinegar was the high acidity of 6.39~6.74% and alcohol was totally converted on the 15th day of fermentation. When we fermented vinegar from peeled roots of 8% PG with a starter culture, we observed high contents of acetic acid, platycodin D, and total polyphenol and high antioxidant activity. Moreover, the vinegar fermented using 8% peeled roots of PG had the high intensity on umami and sour taste and low salty, bitter, and astringent tastes. Consequently, we could develop the PG vinegar with quality and functional characteristics from 8% peeled roots and A. pasteurianus A11-2.

This research was carried out in order to discover acid-forming bacteria during fermentation of Makgeolli, as Makgeolli loses its commercial value due to overproduced acidic materials. In Makgeolli kept at 25℃, a sudden increase of acidity as well as the disappearance of yeast cells occurred at day 6, whereas the total cell count and bacterial type remained unchanged; the result implies that a succession of bacterial types, including acid forming bacteria, occurred. Two acidforming bacteria were isolated from acidified Makgeolli and were identified as Acetobacter pasteurianus and Lactobacillus casei. When fresh and heat-treated Makgeolli were inoculated with Acetobacter pasteurianus and/or Lactobacillus casei, the greatest amount of acid was formed in Makgeolli inoculated with Acetobacter pasteurianus and Lactobacillus casei and also in Makgeolli with Acetobacter pasteurianus alone. This result indicates that Acetobacter pasteurianus is the main acidifier; furthermore, it shows the synergy effect in acid formation with Lactobacillus casei.