## 3 Results
### Aroma Omission Test  
To determine the contribution of non-volatile compounds to the overall aroma of strong-aroma baijiu, we conducted an omission test. The non-volatile compounds were divided into four groups according to their structures (Table 5): organic acids (OM1), sugars (OM2), sugar alcohols (OM3) and alcohols (OM4). One group of compounds was omitted from the full recombination model (Rec B) each time. No difference was observed by triangle test when OM2, OM3 and OM4 groups were omitted from the full model (\(p>0.05\)). When OM1 was absent, the overall aroma profile showed a perceivable difference compared with the full model (\(p<0.001\)). Specifically, the intensity of acidity and fruity decreased, while the perception intensity of alcoholic aroma increased.  
Figure 4: Six aroma attributes with significant differences between Rec A and Rec B. *, significant when \(p<0.05\); **, significant when \(p<0.01\).  
Figure 3: Scores of aroma attributes of the recombination models Rec A and Rec B and baijiu samples.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Number (a)** & **Category** & **Missing Compound** & **Triangle Test** & **Intensity (c)** & **Influence on Aroma** \\  & & & **Significance (b)** & **Intensity (c)** & **Characteristics (d)** \\ \hline \multirow{6}{*}{OM1} & & Lactic acid, Glycolic acid, 2-Hydroxybutyrate acid, Levulinic acid, & & & \\  & & 2-Func acid, Hydroxyicylic acid, 2-Hydroxy-2-methylbutyrate acid, & & & \\  & & 3-Hydroxyovascular acid, 2-Hydroxyroscopic acid, Benzoxide acid, & & & \\  & & Benzenaceace acid, (2-B-Butenedenedic acid, Bottenedic acid, & & & \\  & & Methylogenic acid, (E)-2-Butenedenedic acid, Bottenedic acid, & & & \\  & & & & \\  & & acid, Mandic acid, Michael acid, & Hexanedonic acid, & & \\  & & acid, 2-Therylactic acid, & 4-Hydroxybenzoic acid, Dodecane acid, & & \\  & & & & \\  & & & & & \\  & & & & & \\  & & & & & \\  & & & & & \\  & & & & & \\ \hline OM2 & Carbohydrates (5) & e-D-Mycopyranes, Dr-Protecting, Dr-DiGlucose, D-Trehalose, Sucrose & ns & & \\ \hline OM3 & Sugar alcohols (6) & Erythrified, Xylitol, Arushinitol, Ribitol, D-Mannitol, D-Clicitol & ns & & \\ \hline OM4 & Alcohols (5) & 2-3-Rotanediol, Phenethylamine, Glycerol, Myo-Insositol, & ns & & \\  & & 2-Phenethyl-1,2-propanediol & & & \\ \hline \multirow{6}{*}{OM5} & & Lactic acid, Glycolic acid, 2-Hydroxybutyrate acid, Levulinic acid, & & & \\  & & 2-Func acid, Hydroxyicylic acid, 2-Hydroxy-2-methylbutyric acid, & & & \\  & & 3-Hydroxyovascular acid, 2-Hydroxyoscopic acid, Benzoxide acid, & & & \\  & & & & \\  & & & & & \\  & & & & \\  & & & & & \\  & & & & \\ \hline OM6 & Dbasic acids (10) & 2-Butenedic acid, Malic acid, Hexanedoic acid, & & & \\  & & & & & \\  & & & & \\  & & & & & \\  & & & & & \\  & & & & \\ \hline \hline \end{tabular}  
* a. The aroma emission experiments were conducted by comparing the complete model with models where a specific class of compounds (OM 1-6) was omitted. b. Significance levels are indicated as follows: **\({}^{m}\)** \(\rho\) < 0.001. c. During the test, participants were instructed to numerically rate the differences (0 = invalid, 1 = slightly different, 2 = quite different, 3 = completely different). d. The impact on aroma characteristics of the model when disregarding the specific mixture as represents no significant difference.  
\end{table}
Table 3: Omission test of non-volatiles from strong-aroma baijiu model.  
In order to further analyze the contribution of organic acids to the aroma of strong-aroma baijiu, non-volatile organic acids were further divided into monobasic acid (OM5) and dibasic acid (OM6) for the aroma omission test. The sensory result showed that compared with the full model, the intensity of acidity and fruity notes was significantly reduced in the OM5 sample, but the alcoholic aroma was unchanged. There was no sensory difference between OM6 and the full model (\(p>0.05\)).