Ultrasound–Ethanol Pretreatment-Assisted Enzymatic Method: A Potential Method to Improve the Quality and Yield of Perilla Seed Oil

This study investigates the extraction of perilla seed oil using an ultrasound–ethanol pretreatment combined with aqueous enzymatic extraction (UEAEE). By comparing different pretreatment groups, it was found that the combination of ultrasound and ethanol pretreatment yielded the highest oil extraction efficiency from perilla seeds. Meanwhile, scanning electron microscopy (SEM) analysis further revealed pronounced structural disruption in seeds subjected to ultrasound–ethanol pretreatment, including extensive cellular collapse and the formation of numerous irregular pores and fissures, which facilitated subsequent oil release. The parameters of aqueous enzymatic extraction (AEE) were optimized using a Box–Behnken design. The optimal conditions were determined to be a hydrolysis time of 5 h, a reaction temperature of 52 °C, an enzyme concentration of 5%, and a liquid-to-material ratio of 9.5:1 (mL/g). Compared with oils obtained by pressing extraction (PE) and Soxhlet extraction (SE), UEAEE-derived oil exhibited a higher proportion of unsaturated fatty acids, along with lower peroxide and Acid value (AV), indicating superior quality and a reduced susceptibility to rancidity. Moreover, UEAEE oil retained markedly higher levels of micronutrients (carotenoids: 1.23 mg/kg; total flavonoids: 1.04 mg/g; total phenols: 2.79 mg/g) and demonstrated stronger antioxidant activity (DPPH: 80.60%). Overall, these results demonstrate that UEAEE is an efficient and environmentally friendly extraction method that supports the high-value utilization of perilla seed oil and aligns with modern green processing principles.