Studies on Soong-Neung Flavor 2. Identification of Some Volatile Pyrazine and Carbonyl Compounds of Soong-Neung (extract of cooked and roasted rice)

숭늉향미성분(香味成分)에 관(關)한 연구(硏究) 2. 숭늉향기(香氣)성분중 pyrazine 및 carbonyl 화합물(化合物)에 관(關)하여

Soong-Neung is a Korean traditional beverage served after meals and is made from cooked and roasted rice produced on the bottom of the container during the rice cooking process. The volatiles from the extract of cooked and roasted rice were separated into pyrazine and carbonyl fractions and qualitatively investigated. The pyrazine fraction was characterized by gas chromatography and combined gas chromatography-mass spectrometry and five pyrazines were positively identified. Pyrazine compounds identified are 2-methylpyrazine, 2,3-dimethylpyrazine, 2,5-dimethylpyrazine, 2-ethyl-5-methylpyrazine and 2-ethyl-3-methylpyrazine. Carbonyls were converted to their 2,4-dinitrophenylhydrazones and identified by gas chromatography, combined gas chromatography-mass spectrometry and thin layer chromatography. Acetaldehyde, propionaldehyde, iso-butyraldehyde and iso-valeraldehyde were positively identified in the carbonyl compounds. The aroma of the fractions indentified as 2,3-dimethylpyrazine and 2,5-dimethylpyrazine had a nut-like or roasted cereal-like flavor, which is one of the characteristic flavors of Soong-Neung.

숭늉향기성분(香氣成分)중 carbonyl 화합물(化合物)과 pyrazine 화합물(化合物)에 대하여 살펴 보았다. 숭늉을 질소개스를 유입(流入)하면서 감압(減壓)증류할 때, ice-water trap에 응축된 liquid phase(low volatile flavor)의 증류액을 dichloromethane으로 추출, 농축한 다음 이를 GC, GC-MS로 pyrazine 화합물(化合物)을 분리 동정하였다. 그 결과, 잠정적으로 9개의 pyrazine 화합물(化合物)을 확인하였고 그 가운데 2-methylpyrazine, 2,3-dimethylpyrazine, 2,5-dimethylpyrazine, 2-ethyl-5-methylpyrazine, 2-ethyl-3-methylpyrazine 등 5개의 pyrazine 화합물(化合物)을 동정하였다. 이어 숭늉을 질소개스를 유입(流入), 감압(減壓)증류할 때 얻어진 고휘발성(高揮發性)성분중 carbonyl 화합물(化合物)을 2,4-DNPHs 유도체로 만든 후 이를 GC, GC-MS, TLC 등의 방법으로 carbonyl 화합물(化合物)을 분리(分離) 동정(同定)할 수 있었다. 이들에 대한 관능검사 결과, 특성 pyrazine 화합물(化合物) 특히 2,3-dimethylpyrazine 및 2,5-dimethylpyrazine의 냄새는 구수한 향기(香氣)를 지니고 있는 것으로 보아, pyrazine 화합물(化合物)은 숭늉향기를 이루는 주요한 성분으로 판단되었고 carbonyl 화합물(化合物) 역시 숭늉향기의 일부로서 큰 의의를 지니고 있는 것으로 사료(思料)되었다.