A Novel Method for the Determination of the Ethanol Content in Soy Sauce by Full Evaporation Headspace Gas Chromatography

A full evaporation headspace gas chromatographic (HSGC) method is described for rapid determination of ethanol in soy sauce. The results demonstrated that a near-complete mass transfer of ethanol in the soy sauce sample to the vapor phase (headspace) was achieved within 2 min at 105 °C when a very small (≤40 μL) sample was added to a 20-mL headspace sample vial. The ethanol in the vapor phase was then determined by HSGC using a flame ionization detector. The results showed that the method has an excellent measurement precision (relative standard deviation <0.41 %) and accuracy (recovery = 99.85 ± 1.85 %) for ethanol quantification in soy sauce samples. The method requires no sample pretreatment, so it is a simple, rapid, and sensitive method for the accurate quantification of ethanol content in soy sauce and suitable for applications in food industry.