The objective of this study was to isolate and identify strains of Acetobacter suitable for use in the development of a complex microbial culture for producing Kombucha and to examine the fermentation characteristics for selection of suitable strains. A medium supplemented with calcium carbonate was used for isolation of acetic acid bacteria from 22 various sources. Colonies observed in the clear zone resulting from decomposition of calcium carbonate by acid produced by microorganisms were collected. Identification of the collected strains was based on biological and morphological characteristics, and the results of base sequence analysis. A total of 37 strains were identified, including six species in the Acetobacter genus: Acetobacter pasteurianus, Acetobacter orientalis, Acetobacter cibinongensis, Acetobacter pomorum, Acetobacter ascendens, and Acetobacter malorum, as well as one species in the Gluconobacter genus, Gluconobacter oxydans. Among thirty-seven strains, seven strains of acetic acid bacteria with exceptional acid and alcohol tolerance were selected, and an evaluation of their fermentation characteristics according to fermentation temperature and period was performed. The results showed a titratable acidity of 1.68% for the Acetobacter pasteurianus SFT-18 strain, and an acetic acid bacteria count of 9.52 log CFU/mL at a fermentation temperature of 35 °C. The glucuronic acid and gluconate contents for the Gluconobacter oxydans SFT-27 strain were 10.32 mg/mL and 25.49 mg/mL, respectively.

This study aimed to improve the physiological activity and processing properties of ginseng sprouts. We first determined the effect of extraction and fermentation conditions on the antioxidant activity of ginseng sprouts. The optimal extraction conditions were 2 h at 80°C, with water as a solvent. The fermentation strains used were Lactobacillus delbrueckii subsp. bulgaricus KCTC 3635 and Enterococcus faecalis KCTC 3206. We then analyzed the changes in the reducing sugar and alcohol content. In fermented samples, the reducing sugar content was lower and the alcohol content was higher than those in control sample. The cell counts of lactic acid bacteria were higher in the fermented samples than those in the control sample. Fermented samples contained more ginsenoside than the extract samples, and ginsenoside was not detected in the control sample. The total polyphenol and total flavonoid contents were relatively high in the fermented samples, particularly in the sample fermented by E. faecalis. Finally, sensory evaluation revealed that the Yakju prepared using ginseng sprouts fermented by lactic acid bacteria was preferable to other drinks control and ginseng sprouts extracted sample. Overall, it was confirme that the addition of fermented ginseng improved the physiological activity and palatability of yakju, there by improving the quality of yakju.

The aim of this study was to improve the quality and functionality of Korean soy sauce made with onion juice. At the end of fermentation, the titratable acidity of the soy sauce containing 100% onion juice was the highest at 2.90%. The salt (NaCl) content was highest and lowest in the samples without and with onion juice supplementation, respectively. The protein content ranged from 11.09-12.50%. The sensory evaluation revealed that the soy sauce sample containing 70% onion juice had the highest scove at 5.0-5.8 levels in terms of sweetness, salty taste, delicate flavor, and overall preference. Quercetin content was 1.73 mg/100 g and 1.68 mg/100 g in soy sauce containing 70% and 100% onion juice, respectively. However, quercetin was not detected in the soy sauce without onion juice supplementation. Total polyphenol and flavonoid contents, as well as antioxidant activity, increased proportionally to the amount of onion juice added. Overall, it was confirmed that the addition of onion juice improved the quality and functionality of Korean soy sauce.

This study aimed to select natural materials with antibacterial activity against Streptococcus mutans (S. mutans) KCCM 40105 and determine their most efficient extraction conditions. The antibacterial activity was stable under various treatment conditions. Of the 17 material groups, extracts of Sophora flavescens (SF) and Schisandra chinensis (SC) showed antibacterial activity against the S. mutans strain. Measuring the antibacterial activity based on ethanol concentration revealed that the 30% ethanol extracts of SF and SC showed the highest antibacterial activity as observed by the inhibition zones of 10.69 and 14.49 mm, respectively. The minimum inhibitory concentrations of the 30% ethanol extracts of SF and SC against the S. mutans strain were 2.0 and 5.0 mg/mL, respectively. Heat stability was confirmed; however, the 30% ethanol extract of SC was inactive at pH values ≥6.0. The antibacterial activity of the 30% ethanol extract of SF and SC treated with nine enzymes was the same at 10 ppm and 100 ppm. However, the activity tended to decrease marginally in the 1,000 ppm concentration treatment group.