The demand to develop and produce eco-friendly alternatives for food packaging is increasing. The huge negative impact that the disposal of so-called “single-use plastics” has on the environment is propelling the market to search for new solutions, and requires initiatives to drive faster responses from the scientific community, the industry, and governmental bodies for the adoption and implementation of new materials. Bioplastics are an alternative group of materials that are partly or entirely produced from renewable sources. Some bioplastics are biodegradable or even compostable under the right conditions. This review presents the different properties of these materials, mechanisms of biodegradation, and their environmental impact, but also presents a holistic overview of the most important bioplastics available in the market and their potential application for food packaging, consumer perception of the bioplastics, regulatory aspects, and future challenges.

Multilayer flexible food packaging is under pressure to redesign for recyclability. Most multilayer films are not sorted and recycled with the currently available infrastructure, which is based on mechanical recycling in most countries. Up to now, multilayer flexible food packaging was highly customizable. Diverse polymers and non-polymeric layers allowed a long product shelf-life and an optimized material efficiency. The need for more recyclable solutions asks for a reduction in the choice of material. Prospectively, there is a strong tendency that multilayer flexible barrier packaging should be based on polyolefins and a few recyclable barrier layers, such as aluminium oxide (AlOx) and silicon oxide (SiOx). The use of ethylene vinyl alcohol (EVOH) and metallization could be more restricted in the future, as popular Design for Recycling Guidelines have recently reduced the maximum tolerable content of barrier materials in polyolefin packaging. The substitution of non-recyclable flexible barrier packaging is challenging because only a limited number of barriers are available. In the worst case, the restriction on material choice could result in a higher environmental burden through a shortened food shelf-life and increased packaging weights.

The aim of this review is to provide an in-depth overview on the use of inorganic nano-sized entities for the generation of nanocomposite materials in the form of films and coatings for food packaging applications. According to recent trends toward “green” strategies, special focus has been dedicated to the development of nanocomposite coatings obtained using biopolymers as the main polymer matrix. After a first introductive part, the discussion has been addressed to the use of inorganic fillers, metals and metal-oxides, zeolites, and graphene. For each class of filler, a first ‘in-depth’ description of the most relevant physicochemical properties for the food packaging sector has been followed by case-by-case references to recent developments and envisaged implementations. The technical aspects that may be crucial in the design and end use of (bio)nanocomposite coatings have been covered in the last part of this work, which also includes an updated list of current applications on nano-sized inorganic fillers in the food packaging field.

The antimicrobial and antioxidant potential of zein and zein-wax composite films having different release profiles for lysozyme and mixture of lysozyme, catechin and gallic acid were tested on cold-stored fresh Kashar cheese inoculated with Listeria monocytogenes ATCC 7644. All lysozyme containing films prevented the increase of L. monocytogenes counts in Kashar cheese for 8 weeks at 4°C, but it was only the zein-wax composite films with sustained lysozyme-release rates which caused a significant reduction (- 0.4 decimals) in initial microbial load of inoculated cheese samples. The mixture of catechin and gallic acid improved the in vitro antimicrobial effect of films against L. monocytogenes, but showed no considerable antimicrobial effect in cheese. However, the films containing catechin and gallic acid were effective in preventing oxidative changes in cheese. This study showed the possibility of increasing safety and quality of fresh cheeses by use of active packaging employing natural antimicrobial compounds and controlled release technology. Industrial relevance There has been a growing interest to develop the functional properties of packaging materials and to obtain packed foods with better shelf-life and quality. Active packaging incorporating antimicrobials is one of the most promising areas since application of this method can improve safety of foods by inhibiting pathogenic bacteria or controlling spoilage flora by using minimum amounts of active compounds. Recently, health concerns of consumers and environmental problems related to plastics increased the popularity of using natural antimicrobial substances in edible films and coatings. This work employs a GRAS status natural antimicrobial lysozyme and zein a major by-product of rapidly growing oil and bioethanol industries which can form self-standing films, coatings or casings. The results of this study showed the possibility of using flexible antimicrobial and antioxidant films with controlled release properties in diary industry.Scientific and Technical Research Council of Turkey (108M353

Ultrasound exfoliation of graphite with the assistance of three polysaccharides (nonionic pullulan, cationic chitosan, and anionic alginate) was investigated in this work. The effects of polymer type, initial concentration of graphite, and ultrasonication period on the graphene yield and quality were compared. Under a sonotrode-type ultrasonication treatment for 30 min, graphene aqueous dispersions with concentrations of up to 2.3 mg ml⁻¹ in pullulan solutions and 5.5 mg ml⁻¹ in chitosan solutions were achieved. The obtained graphene nanosheets were characterized as low-defect mono-layer, bi-layer, and few-layer (<5), and formed stable dispersions in water for up to 6 months. The adsorption of pullulan and chitosan biopolymers on the graphene surface as determined by TGA technique was approximately 2.5 wt% and 8.5 wt%, respectively, which accounts for the dispersibility and stability of the graphene sheets in water. Findings arising from this work suggest that pullulan and chitosan are more effective in exfoliating graphite into graphene than alginate due to the different surface free energy and thermodynamic affinity. The polysaccharide-assisted aqueous-exfoliation approach enables the production of water-dispersible graphene with high quality and large quantity, thus providing an industrially scalable route for new potential applications of graphene-based nanocomposites, e.g. in the food packaging industry.

Summary: In this study, antimicrobial activity of zein films incorporated with partially purified lysozyme and disodium ethylenediaminetetraacetic acid (Na₂EDTA) has been tested on selected pathogenic bacteria and refrigerated ground beef patties. The developed films containing 700 μg cm⁻² lysozyme and 300 μg cm⁻² Na₂EDTA showed antimicrobial activity on Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella typhimurium. The application of lysozyme and Na₂EDTA incorporated zein films on beef patties significantly decreased total viable counts (TVC) and total coliform counts after 5 days of storage compared to those of control patties (P < 0.05). Zein films incorporated with lysozyme and Na₂EDTA or Na₂EDTA alone significantly slowed down the oxidative changes in patties during storage (P < 0.05). Redness indices of patties coated with zein films were significantly lower than those of uncoated control patties during storage (P < 0.05). This study demonstrated the potential usage of zein films containing lysozyme and Na₂EDTA for active packaging of refrigerated meat products.