In the past decade, the demand for fast-moving consumer goods has been rapidly rising and is expected to rise further. Among fast-moving consumer goods (FMCG), packed foods and beverages represent the majority. The global middle class that has the biggest demand for FMCG is expected to grow to 5.4 billion by 2030 ^[1][12]. This will lead to bigger volumes of production, a higher usage of raw materials and significant pressure on planetary resources. Across the global food systems, food loss and packaging waste are a widespread issue. Over the ten-year period from 2009 to 2019, packaging waste reached the highest value of 79.2 million tonnes. Paper and cardboard contributed 32.2 million tonnes to the total packaging waste as the main material in the packaging waste stream followed by plastic waste, which amounted to 15.4 million tonnes ^[2][6].

Food waste is another big issue. According to UN Environment Programme’s (UNEP) Food Waste Index Report 2021 ^[3][13], around 931 million tonnes of food are wasted each year. Household food waste generated share is 61%, followed by 26% from food service, with the remaining 13% coming from retail. One of the United Nations Sustainable Development Goals is to halve food waste by 2030. Packaging with its main functions to ensure food safety and guarantee a prolonged shelf life plays a significant role in food waste management. A prolonged shelf life, food security and the mitigation of food and packaging waste are crucial from the environmental point of view, as food waste is one of the major contributors to the global problems of climate change, biodiversity loss and pollution. Food waste is the third biggest source of greenhouse gas emissions ^[3][13]. At the same time, packaging waste reduction is a top priority, with efficient usage and the management of resources being of paramount importance, as well as the mitigation of negative environmental impacts caused by visual pollution and microplastic pollution in the food value chain. Optimal food packaging material selection is required to assure food loss, sustainable resources management and packaging waste reduction.

2. Food Packaging in Circular Economy—Interlinks between Circular Product Design and End-of-Life Treatment

This section will be focused on circular strategies and their relevance to food packaging in its production and disposal life cycle stages. The entire food packaging life cycle includes five stages: preproduction stage (material selection, design and refinement processes), production stage, distribution stage (transportation, storage and product packaging), use of product stage and disposal stage with different scenarios such as reuse, remanufacture, mechanical and biological recycling, incineration or landfilling ^[4][15]. Along with the whole life cycle of food packaging, the preproduction (material) stage is the main contributor to the overall packaging life cycle effects ^[5][16]. Estimates indicate that 80% of product manufacturing costs ^[6][17]) and over 80% of product-related environmental impacts are locked at the product design phase ^[7][18], meaning that circular design is a key factor for the most efficient material flows. Waste management also plays a significant role and can deeply influence environmental impact results in many impact categories ^[8][19]. Both stages, material selection and end-of-life, not only make significant environmental impacts, but also are strongly related to each other, as the choice of the material type affects the choice and availability of its end of life ^[9][20]. Therefore, a deeper look at the relevance of material selection (preproduction) and disposal of food packaging life cycle stages to circular economy, circular design and waste management strategies will be presented. Strategies such as reduce (smarter product manufacture and use), reuse (extended lifespan of product and its parts) and recycle (useful applications of materials), generally known as the “3R’s” or “re-strategies”, refer to circular strategies ^[10][21]. These strategies are integral parts of waste and resources management hierarchy systems and strongly correlate with the product life cycle. While the Waste Management Hierarchy introduced in the Waste Framework Directive (Directive 2008/98/EC on waste) is more focused on the mitigation of negative health and environmental impacts and efficient recycling, the new Zero Waste Resources Management hierarchy (A Zero Waste hierarchy for Europe) integrates social, economic and logistic considerations and highlights the importance of changing consumption habits, rethinking business models and setting waste-free designs as a top priority in the circular economy. The circular economy is defined as a “systems solution framework that tackles global challenges like climate change, biodiversity loss, waste, and pollution”. A total of USD 700 million annual material cost savings could be achieved if a circular economy is implemented in the fast-moving consumer goods industry ^[11][2]. The success factor of the industrial transition to circularity is that this new economy model is regenerative by design. The Circular Design Guide prepared by the Ellen MacArthur Foundation in cooperation with IDEO distinguishes six circular design strategies:

• Product as a service, i.e., offering access to product leasing instead of sole ownership;
• Embedded intelligence, i.e., improving customer experience via integrated smart data management technologies;
• Extension of product life, i.e., product upgrades, repairs or remanufacture before recycling or disposal;
• Smart material choices, i.e., the best available material choice that guarantees the durability, functionality, and integration of recycled contents as well as easy recycling at the end of product’s life cycle;
• Closed loop or take back, i.e., the collection, re-use and recycling of old/used products;
• Modularity, i.e., the availability to divide products into the smaller parts and replace the broken ones or reuse them in another product.

Two circular design strategies are directly applicable in food packaging: smart material choice, considering a product’s end-of-life treatment in the choice of materials and inputs (i.e., durable, biodegradable, recycled or recyclable materials) and closed loop or take back, referring to collections of old or used products and recovering the value of the materials by recycling or reusing them to make new products. The smart material choice circular design strategy (the choice of packaging material), which is applied in the preproduction life cycle stage, directly correlates with all circular re-strategies: firstly, packaging material savings (reduce) could be achieved if optimal material properties and minimum material usage were applied. Secondly, considerations of availability to design reusable packaging instead of single-use packaging must be evaluated. If a reusable design model is selected, material durability should be taken into account. Lastly, material choice is a key factor in mechanical and biological recycling (the last chance for materials to remain in circular material flows) options, meaning that only materials with no negative environmental impacts should be chosen for compostable food packaging and the industrial feasibility of mechanical recycling of materials should be considered if mechanically recyclable packaging is designed. The importance of material choice in the product design stage and the summarized interlinks between circular product design, circular economy and resources management hierarchy, which are relevant to packaging life cycle preproduction (material) and disposal stages. The application of the smart material choice circular design strategy in the food packaging preproduction life cycle stage is a key factor that directly affects the selection of end-of-life treatment and accordingly influences food packaging integration into the circular material flow. When designing food packaging, the durability, functionality, and integration of recycled content as well as material choice for easy recycling should be considered. As mentioned before, the most applicable food packaging material choice is determined by material properties and product requirements. In the next section, the most popular bio-based plastic food packaging applications based on the packaging type (either flexible or rigid) are lreviearnwed.

3. Bioplastic Market and Bio-Based Plastic Food Packaging Applications

Global bioplastics production market share is less than 1% of the more than 367 million tonnes of plastics produced in 2021, reaching 2.41 million tonnes ^[12][22]. In the next five years, the production capacity is expected to triple. The main bioplastic applications are food packaging, making up 48%, which amounts to 1.15 million tonnes of total bioplastic markets ^[12][22]. Currently, bioplastics are successfully applied in flexible as well as in rigid food packaging.

3.1. Flexible Bio-Based Plastic Food Packaging

The global production capacities of flexible packaging made of bioplastics amount to 0.665 million tonnes. The main bioplastic material used for flexible packaging is Poly (butylene adipate-co-terephthalate) (PBAT). PBAT is a fossil-based or partly bio-based polymer. It is fully biodegradable and compostable, but as it relies on fossil-based resources (and all PBAT blends), it does not fit into a circular economy ^[13][9] and is not a subject of this article. Besides PBAT, starch blends, bio-polyethylene (bio-PE) and polylactic acid (PLA) are three main bio-based plastics used in in flexible packaging production (European Bioplastics) that are circular. Starch blends are complex blends in which the starch content is usually lower than 50% ^[14][23]. These biomaterials are mostly valuable for packaging, where biodegradability is an advantage, such as food waste bags. Starch-based materials are not suitable for fully transparent food packaging applications; however, they can be used for semi-transparent films, bags and pouches ^[15][24]. Starch films have a high permeability to water vapor ^[16][25], and due to their hydrophilic nature, they have poor water-resistant properties, which can be improved by adding 10% (wt) kaolin ^[17][26] or, as one of the most recent onstudies has revealed, hydrophobicity could be increased by adding caffeine ^[18][27]. Even though starch blends have a low gas permeability, they are suitable for food packaging as they prolong shelf life ^[19][28]. PLA is highly transparent, but it is rigid and sensitive to tearing; therefore, it cannot be used for stretch films. However, PLA is perfectly suitable for clear films that are used for fresh food, such as vegetables and fruits. Like starch blends, PLA has poor water vapor and oxygen barrier properties, and without additional barrier, this bioplastic is not suitable for long-storage products that are water sensitive and require a high water vapour barrier. While PLA is not suitable, for example, for frozen food or long-shelf-life bakery products ^[20][7], it can be used for fresh/warm bakery products as these do not require a long shelf life, and a high water vapour transition is a benefit. Some research has indicated that PLA nanostructured composites exhibit improved film properties ^[21][22][29,30], and therefore can be successfully applied to a wide range of food packaging, such as margarine ^[23][31] or fresh curd cheese ^[24][32]. Bio-PE, like other drop-in plastics, has an identical chemical structure to fossil-origin PET, polyethylene (PE) and polypropylene (PP) ^[25][33]; thus, their applications for food packaging are identical—clear and stretch films, pouches, and bags.

3.2. Rigid Bio-Based Plastic Food Packaging

The global production capacities of rigid food packaging are lower compared to flexible food packaging and amount to 0.492 million tonnes. PLA is suitable for packaging containers of food, such as vegetables, mushrooms, and berries, and can replace fossil-based polystyrene (PS). Additionally, this bioplastic is used for cups and bottles. However, because of its higher water permeability, it cannot compete with polyethylene terephthalate (PET) in long-shelf-life bottles/containers ^[20][7], although a recent one wasstudy conducted by Aversa et al. ^[26][34] has revealed that it is possible to obtain good quality wine bottles using a PLA/PBSA (poly (butylene succinate-co-butylene adipate)) blend. The possibility of PLA as a replacement for PET bottles has been highlighted in other sources ^[27][28][35,36]. PLA and a starch blend with PLA have an advantage compared to conventional plastic or PE-coated paper and boards that are used in single-use tableware (cups, plates, takeaway food containers, and so onetc.) and cutlery ^[20][7] and are a significant source of packaging waste due to their low recyclability ^[29][37]. Because of the identical chemical structure to fossil origin plastics, applications of drop-in plastics bio-PET and bio-PE for food packaging, as already mentioned, are similar; bio-PET is mainly used for bottles, clear and other trays, and bio-PE is used for trays, caps and food containers.

3.3. Circular Food Packaging

3.3.1. Re-Use

The circular economy approach, the 3R circular strategy and the resources management hierarchy prioritise reuse over recycling (mechanical and biological). This is due to energy savings, efficient resources management, waste generation reduction and littering prevention. Moreover, reusables are a shift toward more conscious consumption. Packaging-free shops ^[30][38], refillable solutions with optimised material use ^[31][39] and global platforms for reuse (the loop) have already been introduced on the market. There are a number of comparative life cycle assessments (LCA) of the environmental performance of reusable and disposable products that provide very case-dependent results and conclusions, depending on the chosen material as well as the LCA methodological choice and assumptions. In most casituationes, reusable packaging is more environmentally friendly ^[9][20] however, there are some casituationes where single use is a preferable option and the main factors are long transportation distances, the number of cycles of reusable packaging, packaging weight and volumes that impact the fuel consumption and space needed. Almeida et al. ^[32][40] analysed a different type of material reusable and single-use cups. IThis st wudy has concluded that reusable PP and glass cups are a better option than PLA single-use cups after around 10 uses. Similar data on the number of cycles were revealed by Cappiello et al. ^[8][19], who compared single-use tableware of PLA-PBS (polybutylene succinate) blend with reusables. The LCA in meal kit packaging performed by Guðmundsson ^[33][41] considered the whole life cycle from cradle to grave and pointed to a conclusion that reusable packaging can mitigate a significant environmental impact on climate change and the depletion of fossil fuels. In industrial practice, flexible food packaging is not reusable. However, one of the latest onstudies on reusable packaging investigated a PLA film enhanced with a 0–3% (wt) nanostructured composite based on silver, titania and graphene fat and oxygen permeability as well as antibacterial activity properties for the new and reused film. The used film after usage was cleaned and washed three times with distilled water and with 95% ethanol, dried in air and applied again. It waThe authors concluded that this PLA film can be reused with a reproducibility of 100% in the situationcase of 0.5% PLA and with a reproducibility of 85% in the situationcase of 3% PLA3 ^[24][32].

3.3.2. Mechanical Recycling

Full material circularity is a priority of a circular economy. Recycling in the 3R strategy is the last chance for materials to remain in circular material flows and is an attractive end-of-life treatment option, where reuse is not applicable or is economically unfeasible. As much as 20% of single-use plastic could be replaced by reusable systems ^[34][42]. Recycling is a favourable option for sustainability, as energy inputs are substantially lower compared with primary resources and influence the GHG balance positively ^[13][9]. Plastic Recyclers Europe ^[35][43] reports that recyclates reduce CO₂ emissions by up to 90%. An LCA  case study with a cradle-to-grave approach in China, where fast food delivery in single-use packaging is a rapid growing sector, revealed that if recycling rates achieve 35% (currently a lot of packaging is incinerated or landfilled), it would reduce the emissions of single-use packaging by 16%, and a further 60% decrease could be achieved if half of the packaging was made of recycled material ^[36][44]. Bio-origin plastic drop-ins (bio-PE, bio-PET) are fully compatible with existing recycling streams and are currently recycled. Other bio-based plastics, such as PLA ^[13][9] or a PLA/PHB-type blend ^[37][45] can likely be recycled; however, because of the small scale, they are financially unattractive. The amount of plastic recycling in Europe equates to over 8.5 million tonnes, with the aim to quadruple this by 2030 ^[35][43]. The Circular Economy for Flexible Packaging (CEFLEX) ^[38][46] initiative reports that only 30% out of 10–14 million tonnes of European end market flexible packaging and other films may be recycled. For the remaining quantity, additional recycling capacities, including mechanical/physical, chemical and biological ones, are needed. The report also highlights the need of improved sorting systems, clear quality requirements and Designing for a Circular Economy guidelines. It is important to note that high recycling rates depend on a set of factors, such as efficient collection by source and post-consumer separation, as well as through a deposit system, and the availability of recycling capacities. Circular product design applications are also important, meaning that products must be designed to assure the easiest available sorting and recycling experience for end-consumers and recycling streams.

3.3.3. Biological Recycling

The best applicable end-of-life treatment depends on sorting and collection systems, waste volumes, the availability of waste processing infrastructure and its properties ^[20][7], such as biodegradation in casituatione of biological treatment. In most situationcases, bio-origin plastic packaging is perceived as biologically recyclable single-use packaging; the reason for this is that essential applications of renewable materials have been developed in order to mitigate single-use plastic visual pollution and negative environmental impacts. An EEA expert on sustainable resource use and waste (Almut Reichel ^[39][47]) indicates that biodegradable and compostable plastics in some cases and for certain applications can help to mitigate environmental plastic pollution, but it is not a stand-alone solution. Odegard et al. ^[13][9] emphasise that composting biodegradable packaging does not produce compost as a final product and the process is CO₂ neutral. In Forcase of digestion treatment, bio-based plastics yield biogas. GHG emissions can be lowered if compostable bio-based plastics have co-benefits.