Synergistic Effects of Pulsed Electric Field (PEF) and Ultrasound (US) Treatments on the Molecular Structure and Bioactivity of Phenolic and Flavonoid Compounds in Fresh Leafy Vegetables

behzadbeizaei¹ morteza jamshid eini²

1) Master s student in Food Industry, Islamic Azad University, Science and Research Branch
2) PhD student in Food Technology, Islamic Azad University, North Tehran Branch

Publication : The second international conference on new approaches in engineering and basic sciences(icnabs.ir)
Abstract :
This study aimed to investigate the synergistic effects of non-thermal technologies, specifically Pulsed Electric Fields (PEF) and Ultrasound (US), on the structural modification and bioactivity of phenolic and flavonoid compounds in fresh leafy vegetables. Spinach (Spinacia oleracea) and parsley (Petroselinum crispum) were selected as representative leafy greens due to their high content of bioactive phytochemicals. Samples were subjected to optimized PEF treatment (electric field strength: 3 kV/cm, 30 pulses, pulse duration: 20 µs) and ultrasonic treatment (frequency: 40 kHz, power intensity: 180 W, exposure time: 10 min), both individually and in combination. Quantification of Total Phenolic Content (TPC) and Total Flavonoid Content (TFC) revealed a statistically significant (p < 0.01) enhancement in compound release under combined PEF-US treatment, with increases of up to 60% in TPC and 45% in TFC compared to untreated controls. Fourier-transform infrared spectroscopy (FTIR) analysis indicated conformational changes in hydroxyl, carbonyl, and aromatic functional groups, corroborating the structural modification of cell wall polysaccharides and phenolic complexes. Scanning Electron Microscopy (SEM) images provided visual confirmation of electroporation-induced membrane disruption and cavitation-induced cell wall degradation, which facilitated solvent penetration and compound diffusion. The antioxidant capacity, assessed via DPPH, ABTS, and FRAP assays, demonstrated significantly improved radical scavenging and ferric-reducing abilities post-treatment. Combined treatments outperformed single PEF or US interventions, suggesting a potentiated effect likely due to enhanced mass transfer and cell permeabilization mechanisms. Statistical modeling using factorial design and Response Surface Methodology (RSM) further validated the synergistic interaction between PEF and US, identifying optimal processing conditions for maximum bioactive recovery. Notably, the combined non-thermal treatment preserved the molecular integrity of sensitive phytochemicals while maximizing their bioavailability, without inducing thermal degradation. In conclusion, the concurrent application of PEF and US represents a promising, sustainable strategy for the intensification of bioactive compound extraction in fresh leafy vegetables. This dual-mode processing approach offers substantial potential in functional food development, enabling the production of nutraceutical-rich ingredients with enhanced antioxidant functionality and minimal structural compromise. The findings support the industrial-scale adoption of integrated non-thermal technologies for clean-label, health-oriented food product innovation.
Keywords : pulsed electric field ultrasound phenolic compounds flavonoids leafy vegetables non thermal processing antioxidant activity molecular structure