Effect of Xanthan Gum on the Preparation and Physicochemical Properties of Citral Pickering Emulsion Film

In this paper, the oil-in-water Pickering emulsion of citral was prepared by a high-speed homogenization method with β-cyclodextrin as emulsifier and xanthan gum as external phase stabilizer, and the emulsion obtained was mixed with chitosan solution to make citral emulsion film by the casting method, then the effects of xanthan gum on the preparation and characteristics of the emulsion film were investigated. The results showed that the addition of 0.2% and 0.4% xanthan gum in the emulsion could reduce the particle size of citral droplets in the film from 2.06 μm to 0.71 and 0.61 μm, respectively, effectively increase the distribution density of oil droplets and prevent the occurrence of oil separation in the process of emulsion film making, and at the same time, the light transmittance of the emulsion film increased from 39% to 43%~44%. Compared with the films without xanthan gum, although the water vapor permeability of the films with 0.2% and 0.4% xanthan gum was increased from 12.02 g·mm/(dm²kPa) to 13.58 and 14.32 g·mm/(dm²kPa), respectively, the tensile strength of the film was improved from 5.85 MPa to 6.96 and 8.77 MPa, respectively, and the elongation at break of the film was also enhanced from 28.87% to 29.43% and 32.16%, respectively, indicating that the addition of xanthan gum in the emulsion could significantly improve the mechanical properties while also reduced the moisture resistance of the film. The citral release experiment of the film showed that the addition of xanthan gum could enhance the slow release effect of citral from the emulsion film.