Innovative Extraction of Phenolics from Longan Seeds through Pulsed Electric Fields

Longan (Dimocarpus longan Lour.) seeds contain high levels of phenolic compounds with significant antioxidant properties. This study aimed to optimize the extraction of phenolics from longan seeds using pulsed electric field (PEF)-assisted extraction. A Box-Behnken design was employed to evaluate the effects of electric field intensity (kV/cm), extraction time (min), and solid-to-liquid ratio on total phenolic content (TPC). The optimal conditions were identified as 2 kV/cm, 9 min, and a 1:30 solid-to-liquid ratio, yielding 2.46±0.04 mg gallic acid equivalent (GAE)/g, a 14% increase compared to conventional maceration (2.16±0.08 mg GAE/g). Scanning electron microscopy (SEM) analysis revealed significant microstructural changes in the seed matrix after PEF treatment, leading to enhanced phenolic compound release. Statistical modeling confirmed the significance of extraction time and solvent ratio, with a strong model fit (R² = 0.9893). Compared to maceration, PEF-assisted extraction demonstrated superior efficiency in both extraction yield and phenolic recovery, reduced processing time, and minimized solvent usage, aligning with sustainable extraction practices. These findings highlight PEF as a promising non-thermal, energy-efficient technique for maximizing the recovery of bioactive compounds from agricultural byproducts.