Multifunctional properties of PBAT with hemp (Cannabis sativa) micronised fibres for food packaging: cast films and coated paper

Hemp (Cannabis sativa) stalk fibres from industry residues were incorporated into polybutylene adipate terephthalate, a synthetic biodegradable polyester, to produce films and paper coatings. The lignocellulosic components and the chemical composition of the fibres were analysed, and the results highlight the bioactivity due to cannabinoids, alkanoids, and lignin, among others, making the fibres attractive for active food packaging. The incorporation, without chemical modification, of 2% (w/w) hemp in the PBAT matrix increased the water vapour permeability of PBAT around 22%. The impact on mechanical properties was determined, and the results show that the PBAT/hemp film is less stretchable but stronger than the pure PBAT film. The incorporation of hemp enhanced significantly the compostability of PBAT. The PBAT/hemp films and paper coatings composted two times faster than those using pure PBAT.info:eu-repo/semantics/publishedVersio

Use of metallic and bimetallic nanoparticles as constituents of active bio-based films

The use of bio-based packaging materials containing metallic and bimetallic nanoparticles is relatively modern technology. In this sense, the food packaging industry has been investigating biological and renewable resources that can replace petroleum-based materials to reduce the environmental impact and at the same time, include new functionalities using nanotechnology. Therefore, the main objective of this work was to develop bio-based poly-lactic acid (PLA) films with Zinc (Zn) and Zinc-Iron (Zn-Fe) nanoparticles (NPs), deposited by magnetron sputtering, and evaluate their effect on the structural and functional properties of the films when the NPs are oxidized to be exposed at 60 % and 96 % relative humidity (RH). The morphology and elemental analysis of the samples were determined by scanning (transmission) electron microscopy (SEM and STEM), and Inductively Coupled Plasma (ICP). The structure of the PLA was monitored before and after NPs oxidation by Fourier transform infrared spectroscopy (FTIR) analysis, and the antimicrobial and color assays were performed by using the zone of inhibition (ZOI) test and a Minolta colorimeter, respectively. Finally, the films were correlated in terms of the deposit conditions, Zn or Zn-Fe concentrations, and thickness. The results revealed PLA films with different morphologies, compositions, and sizes of Zn or Zn-Fe NPs. The samples showed a significant antibacterial and antifungal activity against E. coli, P. aeruginosa, P. fluorescens, S. aureus, and A. niger, and changes of color and opacity for the samples with the smaller thickness when stored at 95 % relative humidity. On the other hand, when the Fe in the films increases, the luminosity of the films decreased as well as their antibacterial activity when compared to the films with pure Zn. Hence, these findings are relevant to the food packaging field since intelligent and active films with multiple properties can be developed.info:eu-repo/semantics/publishedVersio

Novel active biopolymer materials for the food packaging

The presence of residual oxygen inside food packaging can significantly affect the organoleptic properties of food and increase microorganism proliferation, decreasing the shelf-life of the products. In this context, the food packaging industry has been investigating new bio-based environmentally friendly multifunctional materials that act as oxygen scavengers and antimicrobial agents. Therefore, in the present work, a new generation of bio-based active films and fibres containing metallic (Zn) and bimetallic (Zn and Fe) nanoparticles (NPs) is developed. Zinc (Zn) and iron (Fe) nanoparticles (NPs) can enhance oxygen absorption capacity, while the oxidized form of Zn, the ZnO, has relevant antimicrobial properties. The NPs were deposited on poly-lactic acid (PLA) films and PLA fibres (produced by electrospinning) by magnetron sputtering, resulting in two different architectures with dissimilar Fe NPs percentages (0, 10 and 20%). The effect of NPs on the structural and functional properties of the produced materials was evaluated at 60 % and 96 % relative humidity. The morphology and metallic composition of the samples were determined by scanning electron microscopy (SEM), and Inductively Coupled Plasma (ICP), respectively. The oxygen scavenging capacity was measured using a Piccolo sensor connected to sealed vials containing 5% oxygen. Finally, the antimicrobial assay was performed through the zone of inhibition (ZOI) test, and the Zn NPs migration was evaluated using different food simulants. The results showed all PLA films and fibres developed have significant oxygen scavenging capacity, achieving the highest decrease of oxygen with the PLA film containing Zn/Fe-10%. All the samples presented promising antimicrobial activity against E. coli and S. aureus. On the other hand, the migration tests revealed that PLA films and fibres containing Fe showed the lowest migration values when 95% ethanol was used as the food simulant, independently of the Fe percentage. Thus, the developing biopolymers prove to be active materials with multiple properties that could be used in the food packaging industry.info:eu-repo/semantics/publishedVersio

Zn and Zn-Fe nanostructures with multifunctional properties as components for food packaging materials

Metallic and bimetallic nanostructures have shown interesting chromatic and antibacterial properties, and they can be used in various applications. In this work, zinc (Zn) and iron (Fe) nanostructures were produced with different morphologies: (i) pure Zn; (ii) Zn-Fe nanoalloys; (iii) Zn-Fe nanolayers (Zn-Fe NLs); and (iv) Zn nanolayers combined with Fe nanoparticles (Zn NLs + Fe NPs). The aim was to produce components for food packaging materials with active and intelligent properties, including oxygen absorption capacity, chromatic properties, and antibacterial properties. Thus, the morphology, structure, and chemical composition of the samples were characterized and correlated with their oxidation, chromatic, and antibacterial properties. The results revealed a relevant reduction in the coating’s opacity after oxidation varying from 100 to 10% depending on the morphology of the system. All coatings exhibited significant antibacterial activity against S. aureus, revealing a direct correlation with Zn content. The incorporation of Fe for all atomic arrangements showed a negative impact on the antibacterial effect against E. coli, decreasing to less than half the zone of inhibition for Zn-Fe NLs and Zn NLs + Fe NPs and suppressing the antibacterial effect for Zn-Fe alloy when compared with the pure Zn system.This research was supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of the project NANOXYPACK-Nano-sized oxygen scavenger for new active food packaging (POCI-01-0145-FEDER-030789), co-financed by the European Regional Development Fund (FEDER) through the Operational Program for Competitiveness and Internationalization (POCI)–COMPETE 2020. This research is also sponsored by FCT under the scope of strategic funding of UIDB/04469/2020 and UIDB/00285/2020 units.info:eu-repo/semantics/publishedVersio

Active packaging systems based on metal and metal oxide nanoparticles

Summary Active packaging refers to a set of systems usually aiming to protect and extend the shelf life of food. The incorporation of metal (e.g. zinc, silver, copper, and gold) and metal oxide (e.g. zinc oxide, titanium dioxide, and magnesium oxide) nanoparticles into petroleum-based and bio-based polymers has progressively increased for active packaging purposes. These nanoparticles provide to the packaging functional characteristics such as antimicrobial capacity, oxygen scavenging, and photocatalytic activity, as well as better mechanical performance and enhancement of barrier properties. Therefore, the present chapter overviews the incorporation of metal and metal oxide nanoparticles into different materials for the development of active packaging systems with multiple functionalities. The types of metal nanoparticles applied to package materials, the main production methods, and the incorporation of them into the packaging are addressed. Additionally, the main features and limitations related to the effect of metal-based nanoparticles on the packaging properties, as well as the possible particle migration to the food and environment when discarded, are discussed.info:eu-repo/semantics/publishedVersio