Physical modification of Lepidium perfoliatum seed gum using cold atmospheric-pressure plasma treatment

Abstract

In the present study, cold atmospheric-pressure plasma treatments (5 and 10 kV for 4–20 min) were used for the modification of Lepidium perfoliatum seed gum (LPSG). The content of carbonyl and carboxyl groups, as well as the water-solubility of LPSG increased after the plasma treatments; however, the numbers of surface hydroxyl groups decreased when 5kVplasma was used. Molecular weight and polydispersity index of LPSG significantly increased after exposure to the air plasma at 5 kV, whereas a significant decrease in molecular weight and a significant increase in polydispersity was observed with increase in the plasma voltage and treatment time. The molecular conformation of LPSG changed to a more disordered or less ordered form when higher plasma voltage was used. Results demonstrated that cleavage of C–O–C as well as formation of C–O–C bonds occurred during plasma treatments. The elastic components were always higher than the viscous one meaning that all native LPSG and modified gums dispersions had weak gel characteristics. However, plasma treated gums at 5 kV had stronger intertwined network than the native gum. Meanwhile, the viscoelasticity of treated LPSG at 10 kV was weaker than the native one. All modified and unmodified LPSGs dispersions revealed pseudoplastic flow behavior. 5 kV treated samples displayed higher apparent viscosity, while lower values of apparent viscosity was achieved after plasma treatments at 10 kV. Therefore, this study confirms the eminent ability of cold plasma as a means to modify or modulate food polysaccharides properties.