## 3 Results and Discussion
reported no difference in mass transfer, moisture loss, oil uptake, specific volume, hardness, color, and microstructure between traditional deep-frying and electrostatic fried fish skins [26]. Table 2 shows that youtiao without potassium aluminum sulfate would not influence the objective CIE L*, a*, and b* values. However, the browning index (BI) of youtiao samples without potassium aluminum sulfate addition is higher than those of youtiao by different frying methods (Table 2). The difference in color (\(\Delta\)E) and browning index when compared to the control sample indicates that, when the youtiao was vacuum fried, there were smaller \(\Delta\)E values compared with deep-frying and electrostatic frying methods (Table 2). There are no significant differences in the reducing sugar content between the samples of traditional deep-frying method and electrostatic frying methods (Table 3), no matter the youtiao (with or without potassium aluminum sulfate addition). However, deep-fried youtiao without potassium aluminum sulfate contained more acrylamide (2095.2 ppb) than that of the control (421.61 ppb) (Table 3) (\(p<0.05\)). The results of a correlation analysis between the pH and acrylamide content of fried youtiao was positively correlated \begin{table}
\begin{tabular}{c c c c c c} \hline
**Treatments** & **L*** & **a*** & **b*** & \(\triangle\)E & **BI** \\ \hline Control & 75.23 \(\pm\) 4.88 a & \(-\)6.32 \(\pm\) 2.92 a & 51.72 \(\pm\) 3.92 a & 0 & 99.37 \\ TnA & 65.63 \(\pm\) 10.99 a & \(-\)2.24 \(\pm\) 2.22 ab & 51.10 \(\pm\) 5.58 a & 10.54 & 129.60 \\ \hline EA & 71.53 \(\pm\) 8.5 a & \(-\)6.54 \(\pm\) 2.68 a & 49.67 \(\pm\) 4.30 a & 4.24 & 101.62 \\ EnA & 69.81 \(\pm\) 8.44 a & \(-\)4.67 \(\pm\) 3.10 ab & 49.65 \(\pm\) 4.27 a & 6.03 & 108.15 \\ \hline VA & 76.59 \(\pm\) 0.26 a & \(-\)7.49 \(\pm\) 0.04 a & 51.64 \(\pm\) 0.05 a & 1.80 & 94.02 \\ VnA & 70.61 \(\pm\) 0.17 a & \(-\)5.70 \(\pm\) 0.04 a & 51.23 \(\pm\) 0.10 a & 4.69 & 108.22 \\ \hline \end{tabular}
* Expressed as mean \(\pm\) standard deviation (Control \(n=8\); TnA \(n=7\); EA \(n=7\); EnA \(n=7\); VA \(n=3\); VnA \(n=3\)); Values followed by the different letter a,b within each column are significantly different (\(p<0.05\)). Control: Traditional frying + potassium aluminum sulfate; TnA: Traditional frying without adding potassium aluminum sulfate; EA: Electrostatic frying + potassium aluminum sulfate; EnA: Electrostatic frying without adding potassium aluminum sulfate; VA: Vacuum frying + potassium aluminum sulfate; VnA: Vacuum frying without adding potassium aluminum sulfate.  
\end{table} 
Table 2: Effect of traditional frying, electrostatic frying and vacuum frying methods on color values * of fried bread youtiao. (\(r\) = 0.778; \(p\) < 0.01). The acrylamide content and BI of fried youtiao were negatively correlated by the addition of potassium aluminum sulfate in the formulation (\(r\) = \(-\)0.666 and \(-\)0.457, respectively; \(p\) < 0.05). Acrylamide formation was confirmed having a negative correlation with the CIE L* value of solution in a food model system at 180 \({}^{\circ}\)C for 30 min heating [35]. [PERSON] et al. reported that the lower the moisture in potato and at higher frying temperature in the potato, the acrylamide formation in the fried product was higher [37]. The acrylamide content of vacuum fried youtiao, with potassium aluminum sulfate addition, is high, compared to traditional deep-frying and electrostatic frying youtiao (\(p\) > 0.05), although vacuum frying is fried at a lower temperature and the youtiao crust's color is lighter, which would generate less acrylamide. Although, the vacuum fryer removed more water during vacuum frying at lower frying temperatures and decreased water activity more effectively for fried products (Table 1), the acrylamide generation might be more at this processing condition. It needs further detailed experiments to clarify the hypothesis.