Functionalization of Polyethylene (PE) and Polypropylene (PP) Material Using Chitosan Nanoparticles with Incorporated Resveratrol as Potential Active Packaging

Abstract

The present paper reports a novel method to improve the properties of polyethylene (PE) and polypropylene (PP) polymer foils suitable for applications in food packaging. It relates to the adsorption of chitosan-colloidal systems onto untreated and oxygen plasma-treated foil surfaces. It is hypothesized that the first coated layer of chitosan macromolecular solution enables excellent antibacterial properties, while the second (uppermost) layer contains a network of polyphenol resveratrol, embedded into chitosan nanoparticles, which enables antioxidant and antimicrobial properties simultaneously. X-ray photon spectroscopy (XPS) and infrared spectroscopy (FTIR) showed successful binding of both coatings onto foils as confirmed by gravimetric method. In addition, both attached layers (chitosan macromolecular solution and dispersion of chitosan nanoparticles with incorporated resveratrol) onto foils reduced oxygen permeability and wetting contact angle of foils; the latter indicates good anti-fog foil properties. Reduction of both oxygen permeability and wetting contact angle is more pronounced when foils are previously activated by O2 plasma. Moreover, oxygen plasma treatment improves stability and adhesion of chitosan structured adsorbates onto PP and PE foils. Foils also exhibit over 90% reduction of Staphylococcus aureus and over 77% reduction of Escherichia coli as compared to untreated foils and increase antioxidant activity for over a factor of 10. The present method may be useful in different packaging applications such as food (meat, vegetables, dairy, and bakery products) and pharmaceutical packaging, where such properties of foils are desired.

Bioactive Characterization of Packaging Foils Coated by Chitosan and Polyphenol Colloidal Formulations

“…The macromolecular solution of chitosan allows better adhesion of chitosan nanoparticles with the embedded extract and, thus, improved stability of the polyphenols on the foil surface. Moreover, in our approach, coatings exist from nanoparticles dispersed in the remaining chitosan and extract solution, with the strategy that an increase in stability can be achieved by simply incorporating the nanoparticles into another macromolecular layer [20].…”

“…The antimicrobial potential of material was evaluated using a modified ISO22196 method for measuring antimicrobial activity on plastic surfaces (ISO, 2007). After one day of incubation at 37 • C for bacteria and 25 • C for fungi, the number of viable bacteria and spores was determined using the pour plate method, with plate count agar for bacteria and malt extract agar for fungi [20]. For each tested material, the number of viable bacteria and spores per cm 2 of tested material was calculated, and antimicrobial activity (R) was calculated following Equation (1), where Ut is the average of the logarithm of the number of cells/spores in the control, and At is the average of the logarithm of number of cells/spores in treated foils.…”

“…To alleviate these problems, smaller amounts of essential oils can be combined with other antimicrobial compounds. One of the intelligent approaches could be the combination of extracts with polysaccharides as a coating for films [19][20][21][22][23][24] in order to positively change their mechanical, optical or barrier properties and to introduce bioactive properties in a suitable way. The use of antioxidants in synergistic formulation with other biopolymers as nanoparticles, with enlarged contact area compared to conventional antioxidant agents, might allow for a reduction in the amount of active substances, which would act very efficiently while simultaneously reducing and/or avoiding the effect of active substances on the required properties of the base packaging material [25][26][27].…”

“…However, the United States (US) Food and Drug Administration (FDA) approves the use of chitosan as a food additive, with the status GRAS (generally recognized as safe). Therefore, chitosan has an advantage compared to other synthetic polymers, which is reflected in its widespread uses as edible film and food packaging material [20].…”

Physicochemical Characterization of Packaging Foils Coated by Chitosan and Polyphenols Colloidal Formulations

“…It has been shown that films and coatings of chitosan and poly-L-lysine applied to the food package possess inherently antimicrobial properties through inhibiting the microbial growth by causing leakage of intracellular constituents of microbial cells [10,11]. Unfortunately, it has been found that most of the polysaccharides show very poor antioxidant activity [3,12], which is an extremely welcomed property of bioactive packaging materials to retard the natural processes (i.e., the oxidative deterioration of food products such as meat is caused by the degradation reactions of fats and pigments [13]), causing food spoilage by reducing oxygen and moisture. Since essential oils are rich in volatile terpenoids and phenolic particles, they have the potential to inhibit oxidation processes, as well as a wide spectrum of microorganisms [14].…”