Surface and rheological properties of egg white albumin/gelatin dispersions gelled on cold plasma-activated glass

Abstract

Thin layers of egg white albumin/gelatin gel have been formed on glass plates previously treated by cold plasma, using oxygen, air and argon gases. After gelation, the gels were detached from the support and the inner surface previously attached to the plate was investigated. Water contact angles were measured on the detached films and their wettability studied in terms of surface free energy changes induced by the contact with the glass support treated with different gases cold plasma. The effect of increasing concentration of gelatin in the gel was also studied. Pre-treatment with oxygen plasma manifested the most significant changes of wetting properties of the films. A novel method was applied to obtain samples with the same thickness and the viscoelastic properties were measured. As expected, increasing gelatin concentration caused the formation of stronger (higher G*) gels. Gels formed on oxygen plasma treated glass support were the strongest. Optical profilometry was used for the characterization of the gels surface topography. It was found that the surfaces become rougher with the plasma treatment of glass support, no regard which gas was used. Increased roughness of the gels caused a decrease in the contact angles. This paper shows, for the first time in the literature, that even when the gel is not treated directly by cold plasma, but it is obtained on pretreated support, it is an effective method to change its surface and rheological properties.