Preparation, Characterization, and Application of Sodium Alginate/ε-Polylysine Layer-by-Layer Self-Assembled Edible Film

The edible film (LBL film) was prepared by layer-by-layer self-assembly technology using Sodium alginate (SA) and e-polylysine (e-PL) as polyanion and polycation, respectively. The self-assembly method was optimized, the mechanical and physical properties of the optimal LBL film were characterized, and its preservation effect on blueberry was explored. Results suggested that the transmittance of LBL2 film was above 85%, and the appearance was smooth and transparency consistent. We found that the structure was compact and uniform through scanning electron microscopy (SEM). Differential scanning calorimetry (DSC) showed that LBL2 film had excellent thermal stability. And had lower water solubility and inhibitory effect on Alternaria. LBL2 films were significantly effective at inhibiting the growth of mold and maintain the firmness of postharvest blueberries. Compared with the control group, LBL2 films could prolong the shelf life of a blueberry by 1 similar to 2 days at room temperature.