Effect of compound aging treatment on the quality of Nongxiangxing Baijiu

The scientifically combined artificial aging method is one of the most effective approaches for baijiu aging. The present study sought to explore the effects of six compound aging treatment methods on the quality of Nongxiangxing Baijiu, including high-temperature + ultrasonic (G-C), high-temperature + microwave (G-W), microwave + ultrasonic (W-C), microwave + high-temperature (W-G), ultrasonic + high-temperature (C-G), ultrasonic + microwave (C-W). Additionally, the samples of natural aging for 1–2 years (1–2N), 3–4 years (3–4N), and composite aging samples were compared with raw baijiu to explore the inhibitory effect of the composite aging method on the aging time and achieve natural aging, thereby saving costs and increasing economic benefits. The physical and chemical analyses of the nine sample groups were performed according to the national standard GBT10781.1–2021, and the sensory evaluation was performed using the fuzzy sensory evaluation method. The volatile components of the nine sample groups were analyzed by GC-MS, and the OAV activity was calculated. A total of 21 flavor substances with OAV >1 were identified. The natural aging group and the compound accelerated aging group were analyzed using the Orthogonal partial least squares discriminant analysis (OPLS-DA), and 6 and 10 different compounds were found in both groups, respectively. The cluster analysis of the complex aging samples showed that the G-C, G-W, W-C, C-W, C-G, and W-G were in the specific category. Furthermore, the primary flavor substance of Nongxiangxing Baijiu, i.e., ethyl caproate, was positively correlated with the differential compounds caproic acid, butyric acid, ethyl oleate, ethyl lactate, caproate, butyl caproate and ethyl valerate. By principal component analysis (PCA), the W-G group and 3–4N group were consistent in flavor correlation, indicating that the W-G group had a good aging effect. In addition, ethyl palmitate, ethyl oleate and other long-chain fatty acid ethyl esters showed positive correlations with the W-G group and 3–4N group, which is worthy of our further attention and research. • Comparison of natural aging group and compound aging group of Nongxiangxing Baijiu. • OAV analysis identified 21 flavor substances with a value greater than 1. • OPLS-DA: The two groups of samples had 6 and 10 different substances, respectively. • In cluster analysis, W-G belongs to a separate category. • The flavor correlation between the W-G group and the 3–4 year group was consistent.