## 3 Results and Discussion  
### Influence of Lipid on the Release of Baijiu Flavor Substances  
HS-SPME was employed to investigate the impact of peanut lipid on the release intensity of baijiu aroma substances in water solution and 53% ABV solution (Figure 1). Thanks to the small amount of ethanol in the compound stock solution as the solvent, along with a prolonged vortex homogenization and shortened SPME equilibrium extraction time, most compounds had an RSD < 15%. The experimental results demonstrated that in the water solution, peanut lipid promote the release of butyric acid, ethyl lactate, and phenol (\(p>0.05\); log \(p<1.5\) and water solubility constant \(>1.0\), thus being hydrophilic). For compounds with log \(p>1.5\), lipid reduced their release, and for those with log \(p>1.7\) and water solubility constant \(>1.0\) (except for p-cresol), the release was significantly inhibited, suggesting that the influence is associated with hydrophobicity. Figure 1: The influence of peanut lipid on the aroma release of baijiu components. The “*” shows a significant difference in the release intensity of compounds after adding peanut lipid compared to the blank control group. The “*” represents \(p<0.05\), “*” represents \(p<0.01\), and “*” represents \(p<0.001\) in the multiple \(t\)-test. In comparison with the water solution, the release intensities of compounds in the 53% ABV solution decreased. Notably, the releases of nonanol, 2-heptanol, heptanoic acid, octanoic acid, 4-methylphenol, ethyl phenylacetate, and phenylacetaldehyde were significantly inhibited by peanut lipid, indicating an interaction between peanut lipid and baijiu flavor substances. Except for phenylacetaldehyde, p-cresol, heptanoic acid, and isovaleric acid, the inhibitory effect of lipid on compounds in 53% ABV-lipid solution was weakened compared to the aqueous solution. The decreases in release intensities of 1-decanol, ethyl hexanoate, ethyl heptanoate, ethyl octanoate, 4-ethylphenol, nonanal, and trimethyl pyrazine under the influence of the lipid were no longer statistically significant. Both the lipid and ethanol can inhibit the release intensity of the compounds by increasing their hydrophobicity, but there is no additive effect after mixing, resulting in \(1+1<2\). Ethanol and lipid have an antagonistic effect on the release of aroma compounds. To explore the contribution of the physicochemical properties of the compounds to the influence of peanut lipid on baijiu flavor in 53% ABV solution, PCA was used to reduce the dimension of the experimental data (Figure 2). The data before and after adding the lipid were separated by PCA1, which correlated positively with the \(\log p\) value and boiling point of the compounds and negatively with their vapor pressure. The boiling point of the compound relates to its intramolecular hydrogen bonds number, polarity, molecular weight, and volume of the compound. Log \(p\) can characterize hydrophobicity and solvent affinity, while vapor pressure indicates volatility. These properties determine the release pattern of baijiu aroma compounds under peanut lipid. The equilibrium constant indicates the release intensity of the compound in the system, closely related to its solubility (Table 2). When the solubility of the compound is high, the volatility decreases and the equilibrium constant decreases. Compared with the water solution, the equilibrium constant of the compound in the 53% ABV solution decreases. After adding different concentrations of lipid to the 53% ABV solution, the equilibrium constants of most compounds showed a significant decreasing trend and were concentration-dependent. The change in the equilibrium constant of the compound in the 53% ABV solution and the water solution was not significant (Wilcoxon test, \(p>0.05\)), while the 4% and 8% (\(v/v\)) lipid in the 53% ABV solution changed the constant signifi  
Figure 2: The PCA analysis of the influence of peanut lipid on baijiu flavor. cantly (\(p<0.05\)).