Konjac glucomannan-ferulic acid conjugate coatings synthesized via high-voltage electrostatic field: A green strategy for enhancing preservation performance and extending Gastrodia elata shelf-life.

This study reports an innovative, eco-friendly high-voltage electrostatic field (HVEF) approach for synthesizing konjac glucomannan-ferulic acid (KGM-FC) conjugates and evaluates their efficacy as edible coatings for preserving fresh Gastrodia elata. HVEF treatment (10-30 kV, 20 min) successfully induced covalent grafting between KGM and FC, achieving optimal performance at 20 kV with a grafting ratio of 42.93%, significantly higher than physical mixtures (28.83%). Structural characterization using UV-Vis, FT-IR, and SEM confirmed successful covalent bond formation, while XRD and TGA analyses revealed reduced crystallinity and modified thermal stability in the conjugates. The HVEF-synthesized KGM-FC conjugates exhibited enhanced in vitro antioxidant activity (DPPH scavenging >65% at 2.5 mg/mL) and dose-dependent antifungal efficacy (complete inhibition of T. harzianum and F. redolens at 3.2 mg/mL). When applied as edible coatings (1% w/v) via spraying, the HVEF-treated KGM-FC-20 formulation significantly extended G. elata shelf-life during 50-day storage, reducing weight loss by 29.79%, suppressing microbial growth (5.23 vs. 7.69 log CFU/g in control), and preserving flavonoid content (1.61-fold higher than control). This work establishes HVEF as a promising, scalable, and sustainable technology for fabricating functional polysaccharide-polyphenol conjugates with enhanced preservation properties. The resulting coatings demonstrate significant potential for extending shelf-life, maintaining post-harvest quality, and reducing microbial spoilage of fresh produce, offering a green and effective alternative to conventional chemical synthesis methods for food preservation applications. Future studies should investigate the underlying molecular mechanisms of HVEF-induced grafting and explore scale-up feasibility for commercial applications.