Analysis of Volatile Compounds in Aged Fengxiang Crude Baijiu Based on GC-MS and GC-IMS

Targeted at the aged Fengxiang crude Baijiu stored in Jiuhai, a container for Chinese Baijiu, this paper adopted the gas chromatography-mass spectrometry (GC-MS) and gas chromatography-ion mobility spectrometry (GC-IMS) to analyze the changes of volatile substances in the Fengxiang Baijiu. The results indicated that 85 compounds were detected by GC-MS, including 41 esters, 10 acids, 17 alcohols, and some compounds with high molecular weight. During storage, the content of esters decreased obviously, that of acids increased, and that of higher fatty acid esters such as ethyl palmitate, ethyl linoleate, elaidic acid ethyl ester, and stearic acid ethyl ester, and phenylethyl alcohol showed a linear growth. In contrast, a total of 47 compounds, dominated by 23 esters and 14 aldehydes and ketones, were identified by GC-IMS, as it was more sensitive to substances with small molecules. It was found that the content of dipropyl sulfide, isopentane, diacetyl, etc., increased with time. The principal component analysis (PCA) of the two techniques showed that there were significant differences between aged crude Baijiu. Combining the above two techniques, a change law of the volatile components in aged Fengxiang crude Baijiu was derived, the content of acids increased, that of esters declined, and that of ethyl palmitate, ethyl linoleate, elaidic acid ethyl ester, stearic acid ethyl ester, phenylethyl alcohol, benzaldehyde, dimethyl sulfide, and lactic acid grew. It was expected that the results of this paper could provide a theoretical basis for the establishment of the aging system of Fengxiang Baijiu.