Konjac glucomannan-based edible coatings for preservation of Dendrobium officinale

Dendrobium officinale is a nutrient-rich herbal medicine, which often suffer from mildew, dehydration, and other problems during storage. To address the issue of spoilage, we exploited a biomass sourced conformal coating based on konjac glucomannan (KGM) as a matrix, citric acid and ascorbic acid as additives. The KGM-based composite coatings were successfully obtained via the cross-linking and hydrogen bond interaction between KGM matrix and additives. Results showed that the coating material had good film-forming property, high viscosity adhesion, and efficient spreading ability. Furthermore, the composite coatings showed a remarkable enhancement in the inhibition zones against E. coli and S. aureus, and the best antioxidant capacity with ABTS of 86.37 % and DPPH of 81.65 %. These advantages made the KGM-based coatings suitable as conformal material for Dendrobium officinale preservation, which could not only effectively decrease the water loss, restrain oxygen oxidation and microbial infection, but also exhibited better sensory evaluation and higher chlorophyll contents. The composite coatings could effectively extend the shelf life of Dendrobium officinale at least 6 days longer under ambient temperature, indicating a favorable effect on Dendrobium officinale storage. The biobased coatings propose a feasible, cost-effective, and environmentally friendly alternative to conventional synthetic coating for agricultural products preservation.