Changes in Taste Compounds during Onion Vinegar Fermentation

양파초 발효과정 중의 정미성분 변화

Prior research has attempted to develop a method for fermentation of onion vinegar to satisfy customer quality standard. Onion wine (OW) and onion vinegar (OV) were produced by alcoholic and acetic fermentation of onion extracts (OE) using Saccharomyces cerevisiae and Acetobacter pasteurianus, and their taste compounds (non-volatile organic acids, non-protein N compounds, and free sugars) were determined. Main components of non-volatile organic acids were malic acid (50.1%) and citric acid (26.9%) in OE, whereas malic acid (28.1%), acetic acid (20.8%), lactic acid (20.1%), citric acid (13.3%), and succinic acid (12.0%) were detected in OW. Total concentrations of non-volatile organic acids in OV were 4,612.0 mg/100 g, which was 3.9 and 2.3 times higher than those of OE and OW, respectively. Non-volatile organic acids except malonic acid and acetic acid were reduced during acetic fermentation. Non-protein N compounds increased 4.23-fold ($41,526.8{\mu}g/100g$) during alcohol fermentation, and urea content was the highest of non-protein N compounds at $33,816{\mu}g/100g$. The reduced values in OV might be used as a nutritious element of Acetobacter pasteurianus. Free sugars (glucose, fructose, and sucrose) were detected in OE, whereas only fructose was absent in OW and OV.

발효과정(양파 알코올 발효 및 양파 초산 발효) 중의 정미성분을 분석하였다. 유기산의 분석 결과 양파 착즙액(유기산 함량 1,180.8 mg/100 g)에서 malic acid(50.1%)와 citric acid(26.9%)가 대부분의 함량을 차지하였다. 양파 알코올 발효액(유기산 함량 2,008.8 mg/100 g)은 malic acid(28.1%), acetic acid(20.8%), lactic acid(20.1%), citric acid(13.3%) 및 succinic acid(12.0%) 순으로 높은 함량을 차지하였다. 양파 초산 발효액의 총유기산 함량은 4,612.0 mg/100 g으로 양파 착즙액이나 알코올 발효액에 비해 각각 약 3.9배와 2.3배 증가하였으나 acetic acid 이외 유기산의 함량은 감소하였다. 비단백태 질소화합물은 양파 착즙액(총비단백태 질소 함량 $9,803.1{\mu}g/100g$)에 비하여 알코올 발효 후 4.23배($41,526.8{\mu}g/100g$)로 증가하였고, 특히 urea(81.43%)가 두드러지는 증가를 보였다. 양파 초산 발효액은 $2,658.9g/100g$으로 초산균의 생육과 관련하여 소비가 이루어진 것으로 사료된다. 양파 착즙액에 검출된 유리당(포도당, 과당, 자당)은 발효과정 중 과당을 제외하고는 검출되지 않았다.