Antimicrobial releasing edible whey protein films and coatings

Release profiles of potassium sorbate from active-edible whey protein films were determined experimentally and the mechanism of diffusion of potassium sorbate in the films was investigated. The diffusion of potassium sorbate in whey protein films was found to be non-Fickian. A model that described the diffusion of potassium sorbate from whey protein films that swelled due to the countercurrent diffusion of solvent was used to determine potassium sorbate and solvent diffusion coefficients. The diffusivities of potassium sorbate in the films at 25°C ranged from 5.38 to 9.76 × 10 −11 M2/sec. Potassium sorbate diffusion coefficients through the films were significantly affected by the film composition. Increasing the amounts of protein and beeswax in the films decreased potassium sorbate diffusivity. Sorbitol increased the diffusion of potassium sorbate in the films. A rise in the initial potassium sorbate concentration in the films resulted in films with higher diffusion coefficients. Strong interactions were observed between protein and beeswax and potassium sorbate and beeswax. The optimum combination of constituents of whey protein films that provide good mechanical and optical properties was determined using a D-optimal mixture design. Protein, sorbitol and potassium sorbate were important factors influencing film\u27s mechanical properties, while beeswax was the primary factor affecting the transparency of the films. The optimum combination of constituents of whey protein films that provide good water vapor permeability, water solubility and sensory properties was also determined using a D-optimal mixture design. All film constituents had significant impacts on water vapor permeability and water solubility. Beeswax was the most important factor affecting the organoleptic properties of the films. Protein had no effect on stickiness and appearance of the films, while sorbitol had no influence on appearance. Whey protein films with potassium sorbate effectively inhibited the growth of Saccharomyces cerevisiae, Aspergillus niger and Penicillium roqueforti on agar plates by extending the lag period. The higher the initial potassium sorbate concentration in the films, the stronger the microbial effect. These results showed that whey protein films with potassium sorbate could be used as active superficial layers on foods to retard microbial spoilage and prolong shelf life