Effects of Thermal Degradation of Lipids on the Compositions of Fatty Acids and Volatile Components in Mackerel

Abstract

본 연구에서는 생 고등어와 가열 처리한 고등어의 지방산 성분을 Folch-Metcalf 방법으로 추출하여 메틸에스테르화 시켜, GC-MS로 분석하였다. 가열 처리한 고등어에는 총 13 종, 생 고등어에는 총 12 종의 지방산이 분석되었다. 가열 처리한 고등어에서 다가불포화 지방산 (PUFAs)과 포화지방산 (SFAs)이 감소 하였으며, 지방의 산화를 나타내는 acid value (AV)와 conjugated dienoic acid value (CDA) 값이 증가하였다. 이는 지방이 가열 처리로 산화적인 분해가 되어 나타난 결과로 여겨진다. 고등어의 휘발성 향미성분은 solvent assisted flavor evaporation (SAFE)로 추출하여 GC-MS로 분석하였다. 고등어 시료에서는 7 carbonyls, 8 alcohols, 1 terpene hydrocarbon, 31 aliphatic hydrocarbons, 21 aromatic compounds, 1 sulfur-containing compound와 1 nitrogen-containing compound 등 총 70 종의 휘발성 향미 성분들이 확인되었다. 정량적으로 hydrocarbons과 methyl 이나 ethyl기가 치환된 benzenes 이 상당량 검출되었다. 특히, 전형적인 생선 향미 특성을 나타내는 것으로 보고 된 바 있는 2,6,10,14-tetramethylpentadecane 의 함량이 가열 처리한 고등어에서 증가하였다. 또한, 가열 처리한 고등어에서 hexanal, nonanal, 3,5-octadien-2-one과 2-ethyl-1-hexanol이 분석되었고, 1,5-octadien-3-ol, 2,4-heptadienal의 함량이 증가하였다. 기타 가열취를 가지는 benzothiazole의 함량이 가열 처리한 고등어에서 상당히 증가하였다.;Fatty acids were extracted and methylated by Folch-Metcalf method and then analyzed by GC-MS. A total of 13 and 12 fatty acids, including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), were found in raw and broiled mackerels, respectively. The contents of polyunsaturated fatty acids (PUFAs) and saturated fatty acids (SFAs) decreased in the broiled mackerel, maybe due to the thermal degradation of lipids. Also, acid value (AV) and conjugated dienoic acid value (CDA) were measured as indices of oxidation of mackerel. Both AV and CDA increased in broiled mackerel compared to those in raw one. In addition, volatile components in mackerel were extracted by solvent assisted flavor evaporation (SAFE) and then analyzed by GC-MS. A total of 70 volatile components, including 7 carbonyls, 8 alcohols, 1 terpene hydrocarbon, 31 aliphatic hydrocarbons, 21 aromatic compounds, 1 sulfur-containing compound and 1 nitrogen-containing compound, were identified in mackerel samples. Quantitatively, hydrocarbons and methyl and/or ethyl substituted-benzenes were dominant. Particularly, 2,6,10,14-tetramethylpentadecane, which had been reported to have typical fish odor note, increased in broiled mackerel. Also, aldehydes and alcohols such as 1,5-octadien-3-ol and 2,4-heptadienal were enhanced in broiled mackerel. In addition, benzothiazole, which had been known to contribute to roasted odor note, was significantly increased in broiled mackerel.