# Effect of Food Emulsifiers on Aroma Release
## 2 Results and Discussion  
### Influence of Single Emulsifier System on Aroma Release  
The present study found that there existed bonding interactions between emulsifier molecules and aroma molecules, which thereby reduce the concentration of free aroma molecules in aqueous/oil phase and restrict the transfer of aroma molecules from the oil to water phases thus, retaining the aroma. The results showed that the peak areas of ethyl acetate and (_E_)-2-hexenal were one or two orders of magnitude smaller than those of the other studied aroma compounds (3-carene, \(\alpha\)-pinene, limonene, carvone, perillaldehyde). As shown in Figures 1-3 the release of ethyl acetate was significantly (_p_ < 0.05) affected by the concentration of emulsifiers, while no significant differences were observed in different concentrations of xanthan gum solutions (Figure 4). Additionally, the release amount of this compound was two or three order of magnitude lower than those of other aroma compounds. This result indicates that compared with other aroma compounds (3-carene, \(\alpha\)-pinene, limonene, carvone, perillaldehyde), ethyl acetate was more likely to be conserved in the solution system (including the thickening agent, emulsifying agent, or a combination of both). Among all seven aroma compounds, the amount of limonene released was the highest. The lowest release amount of this compound was observed in the presence of 0.4% soybean lecithin. The delayed aroma release was mainly caused by the binding of flavours to emulsifier molecules. The concentration gradient (0.1%, 0.2%, 0.3%, 0.4%, and 0.5%) of Tween 80 affected the release of aroma compounds. As shown in Figure 1a, the release of (_E_)-2-hexenal and carvone showed significant changes for different concentrations of Tween 80 solutions. The amount of ethyl acetate was relatively small, and the peak area of the released ethyl acetate reached the highest level in 0.3% Tween 80 solution. The other three aroma compounds (3-carene, \(\alpha\)-pinene, limonene) also showed the highest peak areas in 0.3% Tween 80 solution (Figure 1b), while all seven aroma compounds showed the lowest peak areas when the concentration of Tween 80 was 0.1%. Figure 1: \(Cont.\)  
The concentration gradients (0.1%, 0.2%, 0.3%, 0.4%, and 0.5%) of soybean lecithin and sucrose fatty acid ester obviously affected the release of these seven aroma compounds. ANOVA revealed a significant effect of different concentrations on aroma release (Figure 2). When the concentration of soybean lecithin was 0.1%, 0.3%, and 0.4%, the peak areas of each aroma compound were much closer to each other. However, when the concentration of soybean lecithin was 0.2% and 0.5%, a peak value that was significantly higher than that of other peak areas was observed. All the aroma compounds had the largest release capacity when the concentration of soybean lecithin was 0.2%. When the concentration was 0.4%, the peak areas of various aroma compounds were the lowest. This implied that when the concentration of soybean lecithin was 0.2%, the release of the aroma compounds was promoted, whereas when the concentration was 0.3% and 0.4%, the release of the aroma compounds was considerably inhibited (Figure 2). Figure 1: Effects of Tween 80 on the release of ethyl acetate, (_E_)-2-hexenal, carvone (**a**) and perillaldehyde, \(\alpha\)-pinene, 3-carene, limonene (**b**). Significant differences (\(p<0.05\)) between different concentrations are performed by letters on the same polylines. Where the letters on the same polyline are the same, there is no significant difference between different concentrations. Figure 2: _Cont._  
The peak area of sucrose fatty acid ester showed a high fluctuation range, indicating that the concentration of sucrose fatty acid ester considerably influenced aroma release. When the concentrations of sucrose fatty acid ester were 0.1%, 0.4%, and 0.5%, the peak area values of each aroma compound had no significant differences (\(p>0.05\)).