Analysis of volatile compounds in fermented and acid-hydrolyzed soy sauces

Abstract

Volatile compounds, isolated by solvent extraction and solid phase microextraction (SPME) in fermented and acid-hydrolyzed soy sauces, were analyzed to compare the difference in flavors between the two samples. A total of 103 compounds were identified and grouped into 12 esters, 14 carbonyls, 16 alcohols, 15 pyrazines, 17 acids, 5 phenols, 1 furanones, 5 furans, 2 lactones, 7 hydrocarbons, 1 pyrones, 2 sulfur-containing compounds, and 6 miscellaneous compounds. Some compounds, such as 3-methyl-l-butanol, 1-octen-3-ol, benzeneethanol, 4-ethyl-2-methoxy-phenol, 2-ethyl-4-hydroxy-5-methyl-3(2H)furanone(HEMF), and methionol, were found only in fermented soy sauce. On the other hand, levulinic acid, formic acid, methional, 2,6-dimethoxy-phenol, diverse pyrazines, 2-acetyl-furan, 2-acetyl-5-methylfuran, and esters were detected only in acid-hydrolyzed soy sauce. Quantitatively, alcohols and esters were dominant in the volatiles of fermented soy sauce whereas the amount of heterocyclic compounds, such as pyrazines and furans, and acids were relatively abundant in acid-hydrolyzed soy sauce. Odor-active compounds were also evaluated using AEDA. The number and variety of odor-active compounds were significantly different in the two soy sauces. The major odor-active compounds of fermented soy sauce were described as strong pungent/sour (acetic acid), rancid (butyric acid), urine-like (benzoic acid), burnt woody/medicinal (guaiacol), sweet HEMF), roasted cocoa-like (2-methyl-butanal), sugar-burnt (furfuryl alcohol), and floral/sweet (benzeneethanol). On the other hand, the major odor-active compounds of acid-hydrolyzed soy sauce were described as strong pungent/sour (acetic acid), rancid/pungent/metallic (formic acid), rancid (butyric acid), urine-like (benzoic acid), burnt woody/medicinal (guaiacol), sweet/caramel (maltol), smoky/woody(2,6-diroethoxy-phenol), roasted cocoa (2-methyl butanal), roasted and nutty (2,5-dimethyl-pyrazine), nutty (2,6-dimethyl-pyrazine), potato/woody (2,5-dimethyl-3-ethyl-pyrazine), and strong nutty (2-acetyl-5-methylfuran).;양조 간장과 산분해 간장의 향미 특성의 차이점을 비교하기 위하여 용매 추출법 (Solvent extraction)과 고체상 미세 추출법 (Solid phase micro extraction)을 사용하여 휘발성 향미 성분을 추출한 후 분석하였다. 총 103개의 휘발성 향기 성분이 동정되었고, 이는 12개의 esters, 14개의 carbonyls, 16개의 alcohols, 15개의 pyrazines, 17개의 acids, 5개의 phenols, 1개의 furanones, 5개의 furans, 2개의 lactones, 7개의 hydrocarbons, 1개의 pyrones, 2개의 sulfur 함유 화합물, 그리고 기타 6개의 화합물로 이루어져 있다. 특히, 3-methyl-1-butanol, 1-octen-3-ol benzeneethanol, 4-ethyl-2-methoxy-phenol, HEMF, methionol과 같은 휘발성분은 양조 간장에서만 동정되었다. 반면에, levulinic acid, formic acid, methional, 2,6-dimethoxyphenol, 다양한 pyrazmes류, 2-acetyl-furan, 2-acetyl-5-methylfuran과 esters 화합물은 산분해 간장에서만 확인되었다. alcohols 화합물과 esters 화합물을 정량적으로 비교하면, 이들 성분들은 양조 간장에서 비교적 더 많이 검출되었고, 반면에 parazmes류와 같은 헤테로고리 화합물과 acids 화합물은 산분해 간장에서 그 양이 상대적으로 많았다. 또한, 두 간장 시료에 있는 향활성 성분들을 Aroma Extract Dilution Analysis(AEDA)를 이용하여 확인하였다. 두 간장에서의 향활성 성분은 다양하게 나타났다. 양조간장의 주된 향활성 성분은 자극적인 강한 냄새/시큼한 냄새(acetic acid), 산패된 냄새(butyric acid), urine과 같은 냄새(benzoic acid), 탄 나무 냄새/약품 냄새(guaiacol), 단 냄새(HEMF), 북은 cocoa 냄새(2-methyl-butanal), sugar burnt한 냄새(furfuryl alcohol), 꽃 냄새/단 냄새(benzeneethanol)와 같이 나타났다. 반면에, 산분해 간장의 주된 향 활성 성분은 자극적인 강한 냄새/시큼한 냄새(acetic acid), 불쾌한 냄새/자극적인 냄새/금속성 냄새(formic acid), 산패된 냄새(butyric acid), urine과 같은 냄새(benzoic acid), 탄 나무 냄새/약품 냄새(guaiacol), 단 냄새/카라멜 냄새(maltol), 훈제 냄새/나무 냄새(2,6-dimethoxy-phenol), 볶은 cocoa 냄새(2-methyl-butanal), 볶은 땅콩 냄새(2,5-dimethyl-pyrazine), 고소한 냄새(2,6-dimethyl-pyrazine), 감자 냄새/나무 냄새(2,5-dimethyl-3-ethyl-pyrazine), 강하고 고소한 냄새(2-acetyl- 5-methylfuran)와 같이 인지되었다.