Physicochemical characterization of plasma-treated sodium caseinate film

Sodium caseinate films were physico-chemically characterized for the effects of atmospheric dielectric barrier discharge (DBD) plasma as function of applied voltage and treatment times. Surface roughness of plasma treated films at both 60 and 70 kV was found to be significantly (p <= 0.05) higher than the control. Glass transition temperature of all the films after plasma treatment was found to be less than the control film. The increase in the O/C atomic ratio shows the formation of new oxygen-containing groups on the film surface. XRD and FT-IR spectra suggest a disruption in the inter-helical structure without any change in the helical configuration of the protein molecules. Increase in the hydrophilicity of the sodium caseinate film was also observed after DBD plasma, but no significant (p> 0.05) increase in the WVTR and OTR was noticed, showing the suitability of the film for novel processes such as in-package plasma decontamination of food. (C) 2014 Elsevier Ltd. All rights reserved.