# Effects of Pulsed Electric Field on Oil Extraction Rate and
## 1 Introduction  
Peony seeds can be pressed for oil, which is not only edible, but also beneficial for human health and natural wellness. Peony seed oil is a type of edible oil made from the seeds of \"Feng Dan\" and \"Zi Ban\" peony, both belonging to the family Paeoniaceae [1]. Peony seed oil has a high content of unsaturated fatty acids at 92%, with polyunsaturated fatty acids (PUFAs) accounting for 70% of that, including over 40% alpha-linolenic acid (which is 140 times higher than olive oil and 10 folds higher than soybean oil), making it highly beneficial for human health. In a study conducted by [PERSON] et al. in 2021 [2], it was revealed that palmitic acid (PA) promotes metastasis in oral carcinomas and melanoma in mice, indicating that consuming plant oils high in PA can be extremely detrimentalto human health. However, poorly seed oil has very low levels of PA. Additionally, poorly seed oil contains tocopherols (especially \(\alpha\)-tocopherol) with antioxidant properties. The content of \(\alpha\)-tocopherol in poorly seed oil is significantly higher compared to other vegetable oils such as olive oil, camellia seed oil, walnut oil, etc., providing significant advantages in skincare and healthcare treatments, reproductive disorder treatments, heart protection, prevention of non-alcoholic liver diseases, as well as anti-tumor effects and diabetes prevention. According to the data from the China Forestry Industry Association, the planting area of oil peony in China exceeded 1.9 million MU (about 126,667 km\({}^{2}\)) in 2021, with an annual production of approximately 53,000 tons of traditional mechanically pressed peony seed oil. Peony seeds have an oil content higher than 22%. If the oil extraction rate can be increased by 5%, the oil production will increase by more than 10,000 tons, leading to significant improvement in economic benefits. In recent years, new technologies such as low-frequency ultrasound [3; 4; 5; 6], microwave [7], high-frequency ultrasound [8; 9], and pulsed electric field (PEF) [10] have been continuously introduced into the process of lipid extraction to enhance extraction efficiency and final product quality. PEF is a non-thermal technology that applies high-voltage pulses ranging from microseconds to milliseconds [11; 12]. The main mechanism for improving oil yield is through increased cell membrane conductivity, resulting in micro-pore formation and subsequent rupture of cell membranes. Depending on the strength of the electric field applied, cell membrane damage can be reversible or irreversible. In reversible damage, pores are closed through rearrangement of phospholipids and proteins. In irreversible damage, pores on cell membranes cannot be closed, leading to loss of cellular integrity [13]. This phenomenon enhances mass transfer and causes leakage of small molecules [14]. Furthermore, it has been reported that PEF applications in mechanical extraction processes for improving juice, oils and other products can increase the content of bioactive compounds while maintaining sensory characteristics of extracted products [15; 16]. Pulsed electric field (PEF) technology has been extensively utilized in plant oil extraction research, with a focus on enhancing oil yield and improving product quality [17; 18]. [PERSON] et al. employed PEF to process sunflower seeds, resulting in a notable increase of 9.1% in oil yield [19]. [PERSON] et al. observed a significant improvement of 13.3% in the extraction rate of olive paste after PEF treatment [18]. [PERSON] et al. obtained that the application of PEF enhanced extraction efficiency without causing any significant impact on refractive index, acidity, acid value, and peroxide value (POV) of hemp seed oil [20]. By utilizing a PEF device for olive paste extraction, the extraction rate increased significantly from 79.5% in the control group to 85.5% [10].