Bioactive packaging based on delipidated egg yolk protein edible films with lactobionic acid and Lactobacillus plantarum CECT 9567: characterization and use as coating in a food model

Abstract Egg yolk is a source of proteins that can be used to develop novel food packaging material. In this study, three different bioactive films were developed using delipidated egg yolk proteins, the first was loaded with a probiotic (PRO, Lactobacillus plantarum CECT 9567), the second one with a prebiotic (PRE, lactobionic acid (LBA), 10 g/L) and the third with both (SYN, containing L. plantarum and LBA). The mechanical properties, water solubility, light transmittance, colour and microstructure of the films were fully characterised. Furthermore, LBA and probiotic concentrations inside the films were monitored under storage conditions. Finally, in order to test the performance of these packaging materials on a piece of real food, gelatine portions were coated by immersion in PRO and SYN film-forming solutions and the microorganism survival after a simulated in vitro digestion was assessed. The strength and water solubility of the films were slightly affected by the presence of LBA at the concentration tested, while the light transmittance decreased in the SYN film in comparison with the other films. Before simulated digestion, PRO and SYN coatings met the minimal requirements to attain the “probiotic” category (6 log10 CFU/g) but after the simulated digestion, only SYN maintained acceptable values. It was noted that the addition of LBA increased the viability of the probiotic, in both the edible films and coatings.