# Effects of Pulsed Electric Field on Oil Extraction Rate and
## 3 Results and Discussion
### Toopherol in Peony Oil  
Tocopherol, also known as vitamin \(E\), is a fat-soluble vitamin with numerous beneficial functions that have been extensively studied. Natural tocoperhools consist of four types of right-handed optical isomers [30], which are named alpha (\(\alpha\)), beta (\(\beta\)), gamma (\(\gamma\)), and delta (\(\delta\))-tocopherol, based on the different positions and numbers of methyl groups on their phenyl rings. Each isomer of tocoperol exhibits varying levels of biological activity, with \(\alpha\)-tocopherol demonstrating the highest degree of bioactivity. Plant food oils are one of the main sources for obtaining tocoperhools in daily life, and there is significant variation in tocoperol content among different varieties of plant oils. Peony seed oil is rich in unsaturated fatty acids, polyunsaturated fatty acids, various vitamins, etc. Therefore, the composition and content of tocoperol can be used as an important index to evaluate the quality of food plant oil. The methods and procedures described in Section 2.4 were employed here to calculate the \(\alpha\)-tocopherol content in the tested oil samples, and their significant differences were analyzed. Where, the statistical significance level was conducted by employing the \(t\) test in Excel software (Microsoft office 2021) with a single tail. The results are presented in Figure 8. To explore the effects of PEF on other tocoperhools, we also investigated the changes in \(\beta\)-tocopherol (represented by \(\beta\)-tocopherol as \(\gamma\)-tocopherol peaks appear at the same time in liquid chromatography) and \(\delta\)-tocopherol content, as well as their significant differences. The results are shown in Figures 9 and 10. It can be observed that, apart from  
Figure 7: Significance level of oil yield before and after 100 Hz (**a**) and 1 kHz (**b**) PEF treatment (* \(p<0.05\), *** \(p<0.001\)). the penoy seed particles with a particle size of 60-mesh, the three types of tocopherols extracted from the seeds have similar levels. Among them, the penoy seed particles with a particle size of 60-mesh have the highest content of \(\beta\)-tocopherol in the extracted oil, which is approximately five times higher than that of \(\alpha\)-tocopherol and three times higher than that of \(\delta\)-tocopherol. As mentioned above, \(\beta\)-tocopherol and \(\gamma\)-tocopherol belong to the same peak in the liquid chromatography. At the same time, \(\gamma\)-tocopherol content in penoy seed oil is much higher than that of other wood oils such as olive oil, so the content of \(\beta\)-tocopherol measured in this paper is higher. After pulsed electric field treatment, the overall \(\alpha\)-tocopherol content in penoy seed particles with particle sizes of 20-mesh and 40-mesh exhibited an increasing trend, as observed from Figure 8. However, for samples with particle sizes of 20-mesh and 60-mesh at low frequencies of applied voltage, a low electric field enhanced the yield of \(\alpha\)-tocopherol while a high electric field inhibited it. Conversely, under high frequencies of applied voltage, all three particle size samples displayed similar trends. Combining with significant difference analysis, the impact of PEF on the content of \(\alpha\)-tocopherol in penoy seed particles extracted oil with particle sizes of 20-mesh and 40-mesh is highly significant compared to the control group, while no significance was observed for samples with a particle size of 60-mesh. According to Figure 9, it can be seen that, regardless of the frequency of the applied voltage, \(\beta\)-tocopherol increases significantly with larger particle size, while the significance of differences weakens as particle size decreases. From Figure 10, PEF treatment did not show a significant effect on \(\delta\)-tocopherol content, indicating that it has an impact on \(\beta\)-tocopherol in penoy seed oil (with a more pronounced effect for larger particles), but has little influence on \(\delta\)-tocopherol content.