Pulsed Electric Field Pre-Treatment for Kaffir Lime Leaf Essential Oil Extraction: Steam and Water Distillation Methods

Kaffir lime (Citrus hystrix) leaves are a valuable source of essential oil widely used in food, pharmaceutical, and cosmetic industries. However, conventional steam and water distillation may result in low oil yields because some essential oil remains trapped within plant cells. This study evaluated the effect of Pulsed Electric Field (PEF) pretreatment on the yield and quality of kaffir lime leaf essential oil extracted using steam and water distillation. A two-factor Completely Randomized Design was applied, consisting of electrode distances of 0.5 and 1.5 cm and PEF treatment times of 10, 20, and 30 s. The treatments were followed by 4 h of distillation. Essential oil yield, specific gravity, refractive index, and volatile compounds were analyzed. PEF pretreatment increased essential oil yield compared with the control. The highest yield (0.6694%) was obtained at an electrode distance of 1.5 cm and a treatment time of 10 s, compared with 0.4745% for the control. The increased yield was attributed to electroporation, which enhances cell membrane permeability and facilitates oil release. PEF treatment did not substantially affect specific gravity (0.8551–0.8651 g/mL) or refractive index (1.447–1.448). GC-MS analysis identified 62 compounds in the best PEF treatment compared with 56 compounds in the control. Thus, PEF pretreatment at 1.5 cm for 10 s improved oil recovery while maintaining essential oil quality.