Understanding the Interaction Between Gelatin and a Layered Silicate and Its Impact on the Physicochemical Properties of Films Produced by Casting

Laponite (R) (Lap) is a synthetic layered nanoclay that is considered a potential candidate for improving the physicochemical properties of gelatin films. However, there is limited information in the literature about the interaction between Lap platelets and gelatin chains and its impact on the physicochemical film properties. Therefore, the current research aimed to systematically study the mechanism of interaction and the effect of Lap on the physicochemical properties of gelatin films (moisture content, optical properties, water contact angle, surface energy, water adsorption, water solubility, water vapor permeability, and mechanical properties). Furthermore, gelatin films with Lap were applied as UV-barrier materials in grape juice. Gelatin films were produced by casting method containing 0, 3, 5, 10, and 15% of Lap (based on the weight of the biopolymer). The incorporation of Lap reduced the formation of the gelatin triple helix structure and consequently film crystallinity. Hydrogen bonds and electrostatic interactions could be the principal interactions between gelatin/glycerol/Lap. The incorporation of Lap increased the thickness and moisture content. Lap platelets were completely exfoliated and did not modify the color and opacity of the gelatin films. The UV-barrier capacity of the gelatin films was improved with the incorporation of Lap. Gelatin films with 15% Lap exhibited a transmittance decreases of 86% and 5% in ultraviolet (280 nm) and visible (470 nm) light, respectively. Furthermore, a reduction of 29% in film water solubility was observed with 15% Lap. Other properties such as water contact angle, surface free energy, water vapor permeability, and mechanical properties were not modified by the incorporation of Lap. Gelatin films containing Lap (15%) reduced the degradation of anthocyanins (50%) in grape juice exposed to UV light when compared with samples covered with gelatin films without Lap.