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Packaging materials play a crucial role in daily life, especially in food preservation, handling, shipping, and storage. Traditional petroleum-based polymers dominate the plastic packaging industry, constituting 26% of total polymer use and experiencing a substantial production increase since 1964. Despite their functionality, plastic packaging raises environmental concerns due to greenhouse gas emissions and pollution from improper disposal.  

To address environmental challenges, the industry is exploring renewable and biodegradable alternatives, such as bio-based plastics, aiming to reduce reliance on nonrenewable resources and lower CO2 emissions. The demand for eco-friendly food packaging is expected to grow as consumers prefer recyclable and environmentally friendly materials. However, uncertainties persist regarding the advantages of bio-based plastics compared to traditional ones.  

The EU Commission targets a 55% recirculation of plastic packaging by 2025 and aims for all plastics to be recyclable or reusable by 2030, aligning with a Circular Economy approach. Sustainability assessments for food packaging should consider factors like zero greenhouse gas emissions, recyclability or reusability, zero landfill waste, reduced water use, renewable energy use, absence of air pollution, and no harm to human health. Despite progress in alternative packaging, there is no perfect solution that fulfills all sustainability criteria while effectively preserving and delivering food.   

Sustainability of food packaging  

The sustainability of food packaging involves meeting present needs without compromising future generations' ability to do the same, particularly focusing on the environmental dimension. Food production significantly contributes to environmental impacts, with 29% of global greenhouse gas emissions attributed to it. To assess the environmental impact and sustainability of food packaging, both the packaging and the food must be considered as a product-packaging combination. Life Cycle Assessment (LCA) is a method used to evaluate the environmental impact of a product-packaging combination throughout its life cycle, considering factors like material sourcing, production, packaging, distribution, and end-of-life. Different models and guidelines, such as ISO 14040 and the European Commission's ILCD Handbook, are available for performing LCA. The assessment should identify relevant impacts, processes generating the highest environmental impact, and provide guidance for system/product improvement. It is crucial to include the indirect environmental impact of packaging on the food product's life cycle, particularly its influence on food waste generation, to avoid recommending packaging that may increase the overall environmental impact of the food-package combination due to potential food losses.  

Production of plastic packaging  

Life Cycle Assessment (LCA) studies indicate that bio-based PLA (polylactic acid) plastics generally offer advantages in climate protection and fossil resource conservation compared to petroleum-based plastics. A meta-analysis of 44 bio-based material cases found lower environmental impacts in the climate change category. However, the choice of feedstock for bio-based plastics production is crucial; using first-generation biomass like maize or starch may compete with crops for human consumption, while waste feedstocks (second generation) are considered more environmentally friendly in LCA.  

Beyond climate change, the environmental impacts of bio-based materials include natural resource depletion, acidification, photochemical ozone creation, eutrophication, human toxicity, and aquatic toxicity. The evaluation shows that bio-based materials may have higher impacts in categories like eutrophication and stratospheric ozone depletion, with variability in acidification and photochemical ozone formation.  

Comparing bio-based PE with petroleum-based PE reveals varying environmental impacts, with bio-based PE showing lower impacts in climate change, summer smog, and fossil resource consumption, but higher impacts in acidification potential, eutrophication, human toxicity, water consumption, total primary energy demand, and land use.  

Regarding end-of-life, composting of plastics is seen as an environmentally attractive option, but not all bio-based plastics are biodegradable. While some biodegradable plastics, such as starch blend polymers and PLA, exist, their degradation can produce significant greenhouse gas emissions in landfills. It's crucial to specify the conditions and timeframe under which a given type of plastic can degrade, as many require controlled industrial composting.  

Recycling of Plastics  

Recycling is considered crucial for environmental sustainability, as it generally involves lower life cycle impacts compared to the production of virgin materials. However, only 14% of plastic is collected and recycled, and most recycled plastics are downcycled into lower-value applications, limiting their ability to enter another round of recycling.  

The potential for recycling plastic waste in the EU remains largely unexploited, with low reuse and recycling rates compared to other materials like paper, glass, or metals. Various factors contribute to this situation, including material losses during product use, improper collection, and degradation during processing (downcycling), stock build-up, product design hindrances, inadequate waste infrastructure, contamination, and economic factors.  

Mechanical recycling, involving sorting, grinding, washing, and extrusion, is the most common method for recycling packaging plastics. However, challenges arise with multi-layer food packaging systems, containing unseparable polymers, and chemical recycling technologies are proposed as alternatives for materials unsuitable for mechanical recycling.  

Bio-based packaging materials, while introducing novel polymers, still require designs for improved recyclability to support the transition to a circular economy. Compostable plastics like PLA face challenges in recycling infrastructure, as they are difficult to distinguish from PET and can contaminate PET recyclates if not effectively sorted.  

Human health risks may arise from contaminants in recycled plastics migrating into packaged food. Potential contaminants include non-authorized monomers and additives, contaminants from misuse, non-food consumer products, chemicals from other packaging materials, and those added during the recycling process. The recycling process must ensure safe contamination levels according to EU regulations, with safety assessments performed by the European Food Safety Authority (EFSA) on a case-by-case basis. Specific criteria for recycling different plastics are established, but more data is needed for a better safety assessment, especially for polymers like PE and PP.  

The discussion on sustainable food packaging emphasizes the growing importance of sustainability in the food industry. Key considerations include producing materials that are safe, environmentally friendly, cost-effective, and produced using renewable energy. While petroleum-based plastics currently dominate food packaging due to their excellent properties, concerns about fossil resource scarcity and environmental impacts, including CO2 emissions, have prompted interest in bio-based plastics.  

Bio-based materials, such as bio-PET, bio-PP, bio-PE, PLA, and PHA, offer alternatives to petroleum-based plastics. Natural biopolymers like polysaccharides and proteins are explored for their abundance, low cost, and biodegradability. However, challenges like hydrophilicity and insufficient barrier properties exist. Improving the production efficiency of bio-based feedstock is crucial for enhancing sustainability.  

The choice of feedstock is crucial; second-generation feedstock from agricultural waste is preferable to avoid conflicts with food production. Recycling is deemed essential for reducing environmental impacts, with mechanical recycling being the preferred method. Challenges arise with multi-layer food packaging systems, impacting the recyclability of bio-based materials.  

Biodegradable or compostable plastics are not a panacea, as landfill disposal contributes to greenhouse gas emissions. Industrial composting may show the highest environmental impacts. The focus on end-of-life considerations in life cycle assessments suggests that recyclability, rather than biodegradability, should be a priority. Designing packaging for recyclability and circularity is crucial for long-term sustainability.  

Innovative plastic packaging materials, whether bio-based or petroleum-based, should prioritize key parameters for sustainability:  

• Optimal Barriers: Materials should have the best possible barriers to enhance food shelf life and minimize food loss  

• Recyclability: Packaging should be designed for mechanical recycling, with a preference for mono plastic materials that maintain functional properties and chemical safety during recycling.  

• Efficient Bio-based Production: Bio-based materials should be efficiently produced from second-generation feedstock to avoid conflicts with food production.  

• Chemicals of Concern: Avoidance of harmful chemicals reduces both environmental and human health impacts, along with lowering waste management costs.  

Bio-based plastic packaging materials are acknowledged for their reduced climate impact compared to conventional materials. However, comprehensive life cycle assessments (LCAs) should consider various environmental impacts of bio-based materials. The overall climate and environmental impacts of packaging/food systems should be assessed throughout their entire lifecycle, with the goal of minimizing environmental burdens through thoughtful design.  

Designing sustainable food packaging is a complex task, requiring consideration of numerous parameters. LCAs serve as valuable tools for quantifying and comparing environmental impacts, providing an informed and holistic foundation for decision-making to enhance the sustainability of food packaging.  

References:  

Ana C. Mendes, Gitte Alsing Pedersen, Perspectives on sustainable food packaging:– is bio-based plastics a solution,Trends in Food Science & Technology,Volume 112, 2021, Pages 839-846, ISSN 0924-2244, https://doi.org/10.1016/j.tifs.2021.03.049.