EFFECT OF PULSED ELECTRIC FIELD INTENSITY AND PULSE NUMBER ON THE EXTRACTION OF PHENOLIC COMPOUNDS AND ANTIOXIDANT ACTIVITY FROM GUAVA SEEDS

The industrial processing of guava (Psidium guajava L.) generates a substantial volume of agro-industrial waste, with seeds representing a highly valuable but underutilized source of bioactive molecules. Recovering these compounds requires efficient and sustainable technologies aligned with circular economy principles. This study evaluated the effect of Pulsed Electric Field (PEF) pre-treatment on the extraction kinetics of total phenolic compounds and the antioxidant capacity (evaluated via DPPH and FRAP assays) from ground guava seeds. A full factorial design was applied to assess the impact of PEF intensity (2, 4, and 6 kV) and pulse number (50, 100, 150, and 200) during a 60-minute extraction process using ethanol as a green solvent. Statistical analyses (ANOVA) demonstrated that both the applied electric field intensity and the number of pulses, as well as their interaction, significantly influenced (p < 0.05) the extraction of phenolics and the resulting antioxidant properties. The optimal extraction condition was achieved using a moderate PEF intensity of 2 kV combined with 100 pulses. Under these parameters, controlled electroporation effectively permeabilized the cellular matrix, maximizing the release of phenolic compounds (reaching approximately 100 mg GAE/g) while preserving their structural integrity and functional capacity as radical scavengers and reducing agents. Conversely, increasing the energy input through higher intensities (4 or 6 kV) or an excessive number of pulses (such as 200) significantly decreased both the phenolic yield and antioxidant activities. High voltages and excessive pulses induced severe cell permeabilization and localized heating (Joule effect), exposing thermolabile phenolic molecules to rapid oxidative and thermal degradation before reaching solvent equilibrium. Additionally, the differences observed between DPPH and FRAP assays under high intensities highlighted the varying sensitivities of hydrophilic and lipophilic antioxidants to the applied electrical energy. Therefore, the precise control of PEF parameters at moderate energy levels is essential to maximize the sustainable recovery of functional antioxidant phenols from guava seeds, offering a promising approach for the development of high-value nutraceutical ingredients.