Abstract
An antibacterial and anti-oxidation composite film was prepared by a casting method using sodium alginate (SA) and apple polyphenols (APPs) as the base material and glycerol as the plasticizer. Silver nanoparticles (AgNPs) were deposited by ultrasonic-assisted electrospray method. The degree of influence of the addition ratio of SA and AgNPs and different ultrasonic time on the mechanical properties, barrier properties, optical properties, and hydrophilicity of the composite film was explored. The composite films were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that the SA: AgNPs ratio of 7:3 and the ultrasonic time for 30 min have the best comprehensive performance, and SA/AgNPs/APP films showed the lowest water vapor permeability value of 0.75 × 10−11 g/m·s·Pa. The composite film has good strength and softness, with tensile strength (TS) and elongation at break (E) at 23.94 MPa and 29.18%, respectively. SEM images showed that the surface of the composite film was smooth and the AgNPs’ distribution was uniform. The composite film showed broad antibacterial activity, and the antibacterial activity of Escherichia coli (92.01%) was higher than that of Staphylococcus aureus (91.26%). However, due to the addition of APP, its antioxidant activity can reach 98.39%, which has a synergistic effect on antibacterial activity. For strawberry as a model, the results showed that this composite film can prolong the shelf life of strawberries for about 8 days at 4 °C, effectively maintaining their storage quality. Compared with the commonly used PE(Polyethylene film) film on the market, it has a greater fresh-keeping effect and can be used as an active food packaging material.
Highlights
In recent years, the research and development of new bio-based materials with biocompatibility and biodegradability to replace petroleum-based plastics needs to be solved urgently [1].Packaging materials that are bio-based, that is, made of proteins, polysaccharides, and lipids, are non-toxic and degradable
Our results showed that the antimicrobial activity of sodium alginate (SA)/AgNPs/apple polyphenols (APPs) was stronger against E. coli than against S. aureus, consistent with the previously reported results [42]
An SA/AgNPs/APP antibacterial and anti-oxidation composite film is prepared by casting film
Summary
The research and development of new bio-based materials with biocompatibility and biodegradability to replace petroleum-based plastics needs to be solved urgently [1]. Packaging materials that are bio-based, that is, made of proteins, polysaccharides, and lipids, are non-toxic and degradable. They provide an excellent barrier, which can effectively protect. Polymers 2020, 12, 2096 food, extend its shelf life, and reduce the environmental impact of traditional packaging materials [2]. SA is widely used in medicine, food, environment, and bioengineering for its excellent properties, such as non-toxicity, wide sources, pH sensitivity, good biocompatibility, and film-forming ability. Traditional SA packaging films without antibacterial or antioxidant activity cannot meet the needs of active packaging
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