Abstract:
For effectively reducing the residual amount of the viscous fluid foods after consumption, the palm wax, candelilla wax and hydrophobic nano-silica were adequately dispersed into absolute ethyl alcohol to form the suspension solution. Afterwards, the suspension was sprayed onto the surface of the common food package materials, which was dried to construct a robust complex wax coating with low surface energy. The scanning electron microscope and Fourier transform infrared spectroscopy were used to analyze the microstructure and components of the complex wax coatings. The yogurt was chosen as typical viscous fluid food to be dropped onto the complex wax coating, which was used to test the yogurt contact angle and rolling angle for exploring the wettability, robust and suitable of the complex wax coating. The typical coarse microstructure was formed on the complex wax coating based on the scanning electron microscope images. The yogurt droplet on the complex wax coating could be easily rolled. Furthermore, the complex wax coatings were fabricated from physical phase transition rather than new chemicals according to the Fourier transform infrared spectroscopy (FTIR). It was shown that the contact angle of yogurt on the wax complex coatings was (142.46±1.29)°, while the rolling angle was (7.80±0.83)°. The abrasion resistance, and pH range of the complex wax coating was further studied. After 40 times friction, the contact angle and the rolling angle of the yogurt on the wax complex coatings were still (135.08±1.94)° and (14.64±0.52)°, respectively. When the complex wax coating onto the substrate was immersed into the lactic acid solutions with pH4 for 24 h, the yogurt rolling angle still maintained (7.29±0.50)°, showing self-cleaning ability. Besides, the rate constant of zero-order reaction kinetics equation of the yogurt residual amount on the original package was 1.02/day, while the rate constant of the yogurt residual amount on the complex wax coating was 0.27/day. It effectively alleviated the yogurt residual amount during storage using the complex wax coating. The complex wax coatings could be further applied in common viscous fluid foods such as milk, coffee, and tomato sauce with residual amount less than 1%, showing great viscosity reduction and loss mitigation. Thus, the complex wax coatings prepared in this study were performed satisfying wettability, anti-abrasion, wide pH suitable range and suitable. It would be provided theoretical basis for reducing high residual amount of the viscous fluid foods on the package surface.