Pulsed electric fields selectivity in peel phenolics from Actinidia deliciosa vs. Opuntia ficus-indica: Triple TOF-LC-MS/MS profiling for valorization

Fruit processing generates large amounts of peel by-products that represent underexploited sources of phenolic compounds with antioxidant potential. This study applied pulsed electric fields technology (PEF) as a green, water-based extraction strategy to valorize kiwifruit ( Actinidia deliciosa ) and prickly pear ( Opuntia ficus-indica ) peels, to determine matrix-specific optimal conditions and assess the selective release of bioactives. A response surface methodology was employed to optimize field strength (kV/cm), specific energy (kJ/kg), and maceration time (h), followed by characterization of the extracts: phenolic content, antioxidant capacity (ORAC, TEAC), pigments, macronutrients, minerals (ICP-MS), and phenolic profiles by LC-QTOF-MS. PEF enhanced phenolic recovery and antioxidant capacity compared to conventional maceration, although the magnitude of improvement was strongly dependent on the matrix. Kiwifruit peel benefited from higher energy inputs, resulting in increased release of phenolics (42.4%), antioxidant capacity (61.8%), and chlorophylls (72.7%), while prickly pear peel achieved better outcomes under low-energy conditions, with moderate increases in phenolic content (30.6%) and antioxidant capacity (39.4%). LC-QTOF-MS confirmed that PEF promoted the release of procyanidins and catechin in kiwi, while preserved kaempferol and quercetin derivatives in prickly pear. Mineral solubilization displayed matrix-dependent trends, with kiwi extracts enriched in Fe, P and K (up to 94.8%), and prickly pear extracts in K, Mg and Cu (up to 95.1%). Overall, PEF should be regarded not simply as an intensification tool, but as a selective technology that requires parameter adjustment according to tissue structure and targeted compound class. This matrix-tailored approach supports the sustainable valorization of fruit peels into antioxidant-rich ingredients.