Preparation of Chlorophyll Oligomer Microcapsules Induced by Pulsed Electric Field to Enhance Stability and Bioavailability of Chlorophyll

Chlorophyll is a natural pigment with diverse bioactivities, but its application is limited by poor stability and solubility. Pulsed electric field (PEF) treatment has emerged as a green, nonthermal method to dissociate chlorophyll aggregates into oligomers, potentially enhancing stability and bioactivity. This study applies PEF technology to induce the microencapsulation of chlorophyll oligomers using whey protein isolate (WPI). The physicochemical and biological properties of the resulting chlorophyll oligomer-WPI (CH–O-WPI) microcapsules were comprehensively evaluated. Results demonstrated that PEF treatment increased encapsulation efficiency by up to 24% (e.g., from 69.13 to 84.46% at 1:1 ratio), and improved water solubility from 58.75 to 87.15%, yielding more uniform particles with a minimal polydispersity index of 0.408 at a 1:2 ratio (P < 0.05). The microcapsules exhibited enhanced color vividness (C* increased by ∼10%) and antioxidant activity (DPPH scavenging activity increased by 5.36%). In vitro digestion and 62-day storage studies demonstrated improved chlorophyll protection and sustained release in PEF-treated samples, with retention up to 56.77%. Notably, the bioavailability of the CH–O-WPI digestion by PEF treatment at the 1:1 ratio increased to 9.88%, compared to 3.30% for free chlorophyll, indicating enhanced cellular uptake. Fluorescence spectroscopy and molecular docking results suggested that PEF induces conformational changes in WPI and modulates chlorophyll aggregate formation, strengthening intermolecular noncovalent interactions such as hydrogen bonding and hydrophobic interactions. These findings suggest that PEF-assisted microencapsulation offers a promising green and sustainable approach to improve chlorophyll stability and bioavailability, although the magnitude of some functional improvements may be modest and influenced by formulation parameters. This approach holds potential for developing functional food ingredients.