Synergistic radio frequency and blue light: a green preservation strategy for fresh Chinese medicicinal herbs via oxidase suppression and bioactive compound stabilization

To address the quality deterioration of genuine Chinese medicinal materials (CMMs) during postharvest storage, primarily caused by polysaccharide degradation, enzymatic browning, and loss of bioactive compounds, this study proposes a green physical preservation strategy utilizing radio frequency synergized with blue light (RF-L). Targeting rhizomes (Arctium lappa roots) and bulbs (lily, Fritillary bulbs), the effects of RF-L treatment (electrode gap 40 cm, blue light irradiation 2 min) on key oxidase (polyphenol oxidase/peroxidase (PPO/POD)) activities, the stability of bioactive compounds (polysaccharides, phenolics, flavonoids, saponins, alkaloids, vitamin C), and antioxidant capacity were systematically investigated. Results demonstrated that RF-L treatment significantly inhibited sensory deterioration, reduced browning in A. lappa roots and lily, alleviated shriveling in Fritillary bulbs, and extended shelf life by over 20%. The treatment synergistically suppressed PPO and POD activities (reduction of 25%–30%), delayed phenolic oxidation, and increased the retention rate of total phenolics in A. lappa roots by more than 15%. Furthermore, RF-L effectively maintained polysaccharide structural integrity (content 10%–20% higher than control during mid-late storage) and significantly enhanced the extraction yield of total flavonoids, key functional components in lily (> 30%). Additionally, RF-L promoted alkaloid accumulation in Fritillary bulbs (+1.5 mg/g during mid-late storage), increased saponin retention in lily by 20%, and markedly strengthened ∙OH scavenging capacity (+37.5%). This mechanism entails suppressing reactive oxygen species (ROS) production and regulating non-enzymatic antioxidant pathways. This study provides the first demonstration of the universality of RF-L technology for preserving diverse organ-type CMMs, offering a theoretical foundation for developing low-energy, chemical-residue-free industrial preservation solutions.