Impact of dielectric barrier discharge cold plasma on Dendrobium officinale polysaccharides: Physicochemical and functional properties

Dendrobium officinale has garnered significant attention due to its notable bioactivity and health benefits. The polysaccharide extracted from Dendrobium officinale (DOP) is the primary source of its functionality. However, its poor solubility and high viscosity necessitate the modification of its physicochemical properties. This study aimed to investigate the impact of cold plasma treatment on the physicochemical and functional properties of DOP. The results indicated that cold plasma treatment substantially increased the solubility of DOP from 87.5 % to 96.30 % and enhanced its hydrophilicity with a lower water contact angle, primarily attributed to the etching effect of plasma. Furthermore, the study confirmed the co-occurrence of cross-linking and depolymerization during the plasma discharge process. The plasma treatment reduced the viscosity of the polysaccharide solution by 10 folds and increased its thermal stability. The microstructure of the polysaccharide, examined by SEM and AFM, revealed that plasma treatment disrupted the cross-linking structure, leading to smooth agglomeration at high intensity. Moreover, the antioxidant capacity and immunoreactivity of plasma-treated DOP have been improved, and the free radical scavenging rate of the plasma-treated could reach 34.40 % at a concentration of 1 mg/mL, stimulating the secretion of cytokines TNF-α (increased 20.70 %), IL-1β (increased 26.94 %), IL-6 (increased 25.32 %), and IL-10 (increased 13.03 %) in in vitro cell tests. Accordingly, cold plasma treatment could be a novel approach to modifying polysaccharides and improving their potential applications in food and pharmaceutical sectors.