NEW PAPER: «Recent advances in polymer-metallic composites for food packaging applications«

REF. : Trends in Food Science & Technology 109 (2021) 230–244 . Q1(2020)JCR 11.07 Material Science.

The use of metallic micro- and/or nanoparticles as inorganic fillers for the improvement of polymer properties is an active trend. This has led to the development of polymer-metallic composites with high potential to be applied in food packaging, due to the enhanced antimicrobial, gas barrier, light-blocking and antioxidant effect in addition to the polymer intrinsic properties. The increasing number of investigations of novel polymer-metallic composites with promising potential and/or already applied as food packaging has raised concern over their efficacy, but also toxicity and environmental impact.

Scope and approach
In this review a critical evaluation of current investigations on polymer-metallic composites, as food packaging options, is assessed. This evaluation emphasizes the enhanced properties provided by the metallic fillers onto the polymer packaging itself, and indirectly in food shelf life, safety and quality. Moreover, awareness regarding the toxicity and environmental impact is also evaluated and related to the migration behaviour.

Key findings and conclusions
Without question, the addition of these type of fillers has the enormous potential to enhance the package properties and, therefore, the food shelf life. Usually, their addition is made alone or in complementation with other fillers allowing a broad spectrum of enhanced properties in the composite film. Despite the advantages, special attention must be paid to the migration form of the filler, in the ionic or the particulate form, that is related to the toxicity and environmental impact of such materials. In overall, the strengths and weaknesses are critically organized, allowing guidance decisions on the implementation of such materials in food packaging.

Diogo Videira-Quintela, ;Olga Martín and Gemma Montalvo.

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TITLE: “Antibacterial LDPE films for food packaging application filled with doped metal-fumed silica hybrids”

Diogo Videira-Quintela,; Francisco Guillén; Gemma Montalvo; Olga Martín.

REF. : Food Packaging and Shelf Life (2020). 1/139 Q1(2019) Food Science & tecnology.ISSN: 0924-2244

Decoration of matrices such as silicates, graphene, etc. is an efficient technique in order to develop multifunctional materials with enhanced properties, which are of use for microbial control. Consequently, it leads to an increased search for alternative matrices and synthesis methods for decoration. Herein, decoration of a fumed silica is proposed, with structures that consisted of silver (Ag@FS), copper hydroxy salt (CuHS@FS), and copper (Cu@FS), for antibacterial applications. With the simple combination of the metal precursor salt, the appropriate solvent, and the fumed silica, the composites were obtained by one-pot solvothermal (200 °C for 1 h), rapid (2 min) microwave assisted precipitation, and by ascorbic acid chemical reduction, respectively. Characterization by powder X-ray diffraction (XRD), thermogravimetric analysis (TGA), and field emission scanning electron microscopy (FE-SEM) proved the successful decoration of the fumed silica with layered copper hydroxy salt (90 width x 970 length nm) and round-like metallic Ag (210 nm) and Cu (370 nm) particles. Fourier transformed infrared (FTIR) and Raman spectroscopy evidenced the presence of Sisingle bondOsingle bondMetal interactions. The antibacterial activity was evaluated against the Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus, giving inhibition and bactericidal values between 3−12 mg/ mL and 12−24 mg/ mL, respectively, with a maximum ion liberation ratio of 1.4 %. The application of the fumed silica presented here, is an attractive alternative to existing matrices, in order to fabricate multifunctional materials, as it is ready-to-use and feasible for large-scale production. Moreover, the applied synthesis routes provide rapid approaches for decoration, creating composites useful for antibacterial applications.

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