Analyzing the Chemical and the Physical Characteristics of Crosslinked Zein Gel Films Cast from Acetic Acid Solutions

摘要

Zein is the most abundant protein found in corn and large amounts are obtained as a byproduct of ethanol production. Zein is amphiphilic and insoluble in pure water and is highly soluble in various ethanol/water solutions and acetic acid/water solutions. Zein has a wide range of utilization area. Its film forming capabilities makes zein one of the most commonly chosen plant-based materials for creating various analytical platforms. In this study biodegradable zein gel films were produced by solution casting and the mechanical, chemical and surface properties of the films were analyzed with different techniques. 70% acetic acid aqueous solution was used as the solvent due to its good dissolution properties for zein and due to its ability to produce very smooth surfaces with excellent surface topography. The concentration of zein was kept constant at 1:5 (g/ml) ratio. Oleic acid was used as a plasticizer at a 1:1 (g/g) zein to oleic acid ratio to increase flexibility and ductility of the film. For a better blending of the plasticizer into the zein matrix, monoglyceride at a 1:0.15 (g/g) oleic acid to monoglyceride ratio was used as the emulsifier. This study particularly focuses on the effect of crosslinking on the surface, mechanical and chemical properties of zein gel films. Glutaraldehyde was used as the crosslinker and was added to the zein solutions in different ratios and the solutions were allowed to crosslink for 20 hours after sonication. The solutions were cast on cured PDMS films and dried under the fume hood until complete evaporation of unbound solvent was obtained.