Energy-Dependent Effects of Pulsed Electric Field (PEF) Treatment on the Quality Attributes, Bioactive Compounds, and Microstructure of Red Bell Pepper

This study evaluated the energy-dependent effects of pulsed electric field (PEF) treatment on the physicochemical properties, bioactive compounds, antioxidant activity, and microstructure of red bell pepper (<i>Capsicum annuum</i> L.). Red bell pepper tissue was treated at specific energy inputs ranging from 1 to 10 kJ/kg and compared with a fresh (untreated sample). The cell disintegration index (CDI) increased progressively with PEF energy, confirming enhanced membrane permeabilization and structural disruption. Structural analyses (SEM and micro-CT) confirmed the formation of pores and interconnected channels, particularly at moderate and high energies. PEF treatment caused a decrease in total polyphenols and flavonoids, whereas vitamin C and total carotenoid contents increased at intermediate energies. Antioxidant activity (ABTS, DPPH, FRAP) declined overall but remained at comparable levels for mild PEF exposure. A significant reduction in firmness was observed (from 17% to 27% compared with the untreated control), and color changes were dependent on the energy input, while microstructural degradation intensified as the energy level approached 10 kJ/kg. PEF treatment improved microbial stability, resulting in a measurable reduction in total viable counts and yeast and mold counts, particularly at higher energy inputs. FTIR, TGA, and NMR data confirmed molecular alterations without degradation of major components. Multivariate analysis (dendrogram, PCA) distinguished four characteristic response groups: fresh, low-energy (1-2 kJ/kg), moderate-energy (4-5 kJ/kg), and high-energy (10 kJ/kg). PEF treatment selectively modified red bell pepper tissue, enhancing permeabilization and carotenoid/vitamin C release while preserving visual quality at mild-moderate energies. These results demonstrate the potential of PEF as a nonthermal technique for tailoring the structural and functional properties of plant-based products.