Effects of Different Storage Containers on Flavor Compounds in Feng-Flavor Baijiu

In order to explore the effects of storage containers on the volatile components of baijiu, gas chromatography (GC), headspace solid-phase microextraction coupled to gas chromatography-mass spectrometry (HS-SPME-GC-MS), and ultra-high performance liquid chromatography (UPLC) were used to analyze the volatile components of baijiu stored in Jiuhai, a pottery jar and a stainless steel tank as well as fresh baijiu. Five classes of compounds, including esters, alcohols, acids, aldehydes, ketones and phenolics, were identified. The results showed that the fresh sample contained the smallest number (79) but largest amount (7756 mg/L) of volatile components. Jiuhai stored sample contained a relatively large variety (94) but the least amount (4276 mg/mL) of volatile components. The samples stored in the pottery jar and the stainless steel tank contained the largest number (96) of volatiles components, and the total amounts of volatile components in them were 5957 mg/L and 5360 mg/L, respectively, lower than those in the fresh sample but higher than those in the Juihai stored sample. Furthermore, principal component analysis (PCA) and heat map analysis showed that for the baijiu stored in the pottery jar and the stainless steel vessel, there was a high correlation among isoamyl alcohol, isobutanol, ethyl laurate, hexanoic acid-2-phenyl ethyl ester, furfuryl hexanoate and acetal, which have flowery and fruity aroma characteristics. However, the Jiuhai-stored baijiu showed a strong correlation among ethyl octadecanoate, ethyl linolenic acid, ethyl tetradecanoate, phenyl ethanol, and benzaldehyde, which have flowery, fruity, honey-like and almond-like aroma characteristics. The effects of storage containers on the volatile components in stored baijiu may be related to the gas permeability and the transition metal ion-releasing capacity of the storage containers and the pH change during baijiu storage.