Onion vinegar, which has an undesirable flavor and taste formed through alcohol and acetic acid fermentation, possesses additives that can improve sensory quality. Thus, the objective of this study was to present an optimized blending ratio using response surface methods for an onion vinegar beverage by adding Omija extracts. This study was performed to formulate an Omija-onion vinegar beverage (OOVB) and investigate its antioxidant properties and antimicrobiological effects. The experimental design was conducted using an optimal mixture model of response surface methodology which generated eighteen experimental trials with overall acceptance as the responses. According to the statistical analyses, OOVB demonstrated a ratio containing onion vinegar, water, brown sugar, apple extracts and Omija extracts of 10, 72.3, 4.4, 12.2 and 1.1 (weight ratio), respectively. The OOVB revealed desirable nutrition values (phenolics compounds 19.3 mg/100 g, total flavonoids 3.1 mg/100 g, quercetin 1.9 mg/100). The OOVB displayed antibacterial effects in Gram negative Enterobacter aerogenes, Escherichia coli, Salmonella typhimurium and Gram positive Staphylococcus aureus. The findings revealed that OOVB was 18% in DPPH radical inhibitionand 11% in superoxide dismutase-like activity thus, OOVB has nutritional value and good quality as well as potential biological activities for functional beverages.

Acetic acid bacteria strains were isolated from a variety of fermented foods and fallen fruits. Among them, the strain MAK88, whose acetic acid fermentation ability, acid-tolerance, and alcohol-tolerance were high, was selected and identified as Acetobacter orientalis. A seed culture of A. orientalis MAK88 was inoculated into onion juice, and the optimum conditions of acetic acid fermentation was investigated. The optimum initial concentration of ethanol in onion juice was 5% (v/v) and in that condition, acidity was 4.31% at 144 h of fermentation. The optimum initial concentration of acetic acid was 1% and the final acidity was 5.32%. The optimum fermentation temperature was determined to be 28oC. The most appropriate preparation method of onion juice was to heat the onion at 121oC for 15 min and produce juice with pressure followed by filtering, and then sterilization at 121oC for 15 min. Prepared onion juice was used for fermentation without dilution.

This study aimed to provide volatile flavor compounds of three onion products through thermal process and alcohol fermentation, to meet the quality standard of onion products. The identified components of onion extracts (OE) included 49 (18 sulfur-containing compounds, 5 alcohols, 8 acids, 3 ketones, 4 esters, 4 aromatic compounds, 2 aldehydes, 1 pyrazines and 4 miscellaneous compounds), and 55 (17 sulfur-containing compounds, 15 alcohols, 5 acids, 11 ketones, 3 aromatic compounds, 2 aldehydes and 1 pyrazine) in autoclave-sterilized onion extracts (SOE); and 69 (10 sulfur-containing compounds, 27 alcohols, 11 acids, 11 ketones, 6 esters, 1 aromatic compound and 3 pyrazines) in onion wine (OW), respectively. Among the major flavor classes, sulfur-containing compounds (36.8%), acids (31.3%) and aldehydes (13.6%) in OE were changed to alcohols (46.5%) and ketones (27.3%) in SOE whereas, alcohols (56.3%) and acids (26.6%) in OW. Moreover, 1,3-butanediol, 2,3-butanediol, and 3-hydroxy-2-butanone were highly detected in SOE whereas, acetic acid, 3-methylbutanol, 2-phenylethanol and 1,2,3-propanetriol in OW.

Commercialized production of onion vinegar, which has biological activities formed through alcohol and acetic acid fermentation, requires standardization. The objective of this study was to determine optimal conditions of sugar contents (11~15 °Brix) and agitation rate (100~300 rpm) of fermenter in the alcohol-acetic fermentation for producing onion vinegar. The alcohol and total acidity contents increased, whereas contents of total sugars decreased during alcohol fermentation. Contents of alcohol of 13 and 15 °Brix reactants were about 8% in 36 hr and total acidities of all samples were below 0.2% in 60 hr. During acetic fermentation, total acidity increased with highest value at 9 days (3.2% in 100 rpm), 10 days (4.1% in 200 rpm) and 8 days (4.3% in 300 rpm), respectively. From these results, sugar contents (13 °Brix) were measured for alcohol fermentation and agitation rate (300 rpm) for fast fermentation method of vinegar. The contents of total phenols, flavonoids and quercetin in onion vinegar were 33.3 mg/100 g, 3.0 mg/100 g and 2.0 mg/100 g, respectively. Onion vinegar showed an antimicrobial activity against Bacillus cereus, Staphylococcus aureus, Listeria monocytogenes, Salmonella typhimurium, Escherichia coli and Enterobacter aerogenes. Antioxidant effect of onion vinegar was 26.23% in DPPH radical inhibition and 58.58% in superoxide dismutase like activity, respectively. Fibrinolytic activity was 1.51 plasmin unit/mL in onion vinegar. In conclusion, onion vinegar processed by alcohol and acetic fermentation had nutritional values and potential biological activities.

양파의 냄새를 줄이고 기능성을 살린 식초의 제조를 위한 기초 연구의 일부로서 양파즙에 보당하여 알콜 발효하는 대신에 알콜 발효 없이 양파즙에 에탄올을 첨가한 양파식초의 제조에서 flavonoid 물질의 함량변화, flavonoids를 강화한 양파식초의 제조방법 및 이들 물질의 초산에 대한 안정성을 조사하였다. 양파즙의 식초발효에서 , 10분 열처리하여 착즙한 양파액에 에탄올을 첨가한 양파식초에서 초산생성량이 높았다. Flavonoids의 함량은