Preparation and characterization of sodium alginate/gelatin/Ag nanocomposite antibacterial film and its application in the preservation of tangerine

With the increasingly serious problem of environmental pollution caused by non-degradable petroleum-based packaging materials, there is an urgent need to develop an environmentally friendly packaging material. In this study, a food packaging coating with good antibacterial effect was prepared by adding silver nanoparticles (AgNPs) into a mixture of sodium alginate (SA) and gelatin (GL). The film formed by coating (SA/GL/Ag film) has good mechanical properties, and its tensile strength and elongation at break are 46.0 MPa and 17.1 %, respectively. By measuring the hydrophilic properties of the film, it was found that the SA/GL/Ag film has a very low water contact angle (WCA = 40.13°) and good water solubility. By measuring the inhibition zone size of the film against food-borne pathogens, the results showed that SA/GL/Ag film has significant antibacterial activity against both S. aureus and E. coli. Finally, the coating was used for the preservation of tangerines, and it was found that the SA/GL/Ag coating could slow down the loss of nutrients and prolong the shelf life of tangerines. In conclusion, SA/GL/Ag coating (film) has broad application prospects in the field of food packaging.