title: Simple method for the simultaneous quantification of medium-chain fatty acids and ethyl hexanoate in alcoholic beverages by gas chromatography-flame ionization detector: development of a direct injection method.
abstract: Free medium-chain fatty acids (MCFAs) can negatively influence the fermentation process and taste quality in alcoholic beverages. Ethyl hexanoate is important in providing a fruit-like flavour to drinks, particularly in Japanese sake. In this study, we developed a direct injection method for a gas chromatography-flame ionization detector following the semi-purification of chemical components, such as esters, alcohols and MCFAs in alcoholic beverages. Evaluation of MCFAs by this method gave a limit of detection on the order of sub-ppm and relative standard deviations less than 10% in standard solution. Good repeatability and recovery rates against MCFAs and ethyl hexanoate were also obtained in non-distilled real alcoholic beverages. Because this method enabled us to simultaneously quantify the concentrations of MCFAs and ethyl hexanoate, the proportion of ester against MCFAs was proposed as a quality control index. This method could be suitable for routine analysis in the alcohol beverage industry.
authors.affiliation: National Research Institute of Brewing, Fundamental Research Division, 3-7-1 Kagamiyama, Higashi-hiroshima, 739-0046, Japan. k.takahashi@nrib.go.jp
authors.forename: Kei
authors.initials: K
authors.lastname: Takahashi
authors.forename: Nami
authors.initials: N
authors.lastname: Goto-Yamamoto
mesh_terms: D019840:2-Propanol / Q000737:chemistry; D000434:Alcoholic Beverages / Q000032:analysis*; D002208:Caproates / Q000032:analysis*; D005227:Fatty Acids / Q000032:analysis*; D005410:Flame Ionization / Q000379:methods*; D015203:Reproducibility of Results
chemical_list: D002208:Caproates; D005227:Fatty Acids; C079237:ethyl hexanoate; D019840:2-Propanol