A Guide to Biodegradable Packaging Materials

What distinguishes biodegradable packaging

The term "biodegradable" in a packaging context refers to materials that decompose through biological activity — typically the action of microorganisms including bacteria and fungi — into water, carbon dioxide, and biomass. The rate and conditions of degradation vary substantially between material types.

Under standard EN 13432, a material qualifies as industrially compostable if it achieves at least 90% disintegration within 12 weeks and reaches 90% biodegradation relative to a reference material within 6 months at 58°C. This is the operative standard for compostability certification in the EU and Poland.

Not all biodegradable materials meet EN 13432. Some degrade only in soil or marine environments under different timeframes. Producers must distinguish between industrial compostability, home compostability, and biodegradability in uncontrolled environments when selecting materials and making label claims.

EN 13432 is the primary EU and Polish standard for industrial compostability. Products certified under this standard may carry the seedling logo issued by DIN CERTCO or TÜV in Germany, or equivalent bodies.

Polylactic acid (PLA)

PLA is a thermoplastic polyester derived from fermented plant starch — most commonly maize, sugarcane, or cassava. It is the most widely adopted biopolymer in rigid packaging applications including cups, lids, trays, and clamshells.

Performance characteristics

PLA has a glass transition temperature of approximately 55–60°C, which limits its use in hot-fill applications without modification. Crystallized PLA (CPLA) — produced by controlled cooling — raises the heat resistance to around 90°C, making it suitable for hot beverage lids and microwave containers.

Barrier properties are moderate: PLA has reasonable oxygen barrier characteristics but poor moisture vapour transmission resistance compared to PET. For food applications requiring extended shelf life, PLA is often combined with EVOH or mineral coatings.

Composting conditions

PLA requires industrial composting conditions — temperatures above 50°C and controlled humidity — for reliable degradation within the EN 13432 timeframe. It does not degrade meaningfully in home compost piles or in the soil under ambient conditions. Contamination of anaerobic digestion streams with PLA is problematic, as it does not degrade anaerobically.

Polyhydroxyalkanoates (PHA)

PHAs are a family of biopolyesters produced by bacterial fermentation of carbon substrates including glucose, fatty acids, and waste streams. Unlike PLA, PHAs biodegrade in soil, freshwater, and marine environments under ambient conditions, making them relevant to applications where post-use collection is unreliable.

PHB (polyhydroxybutyrate) and PHBV (polyhydroxybutyrate-co-valerate) are the most commercially available PHA variants. PHBV is used in films, flexible sachets, and coatings. Production costs for PHA remain significantly higher than for PLA or conventional plastics, which restricts uptake to premium or regulated applications.

Paper-based and fibre composites

Moulded pulp — produced from recycled paper or virgin fibre — is the dominant biodegradable substrate in food service packaging, including egg trays, fast food containers, and protective inserts. Moulded pulp is inherently biodegradable and home-compostable without chemical modification.

The primary limitation is moisture resistance. Uncoated paper and pulp lose structural integrity when wet, which restricts use in direct food contact applications without barrier treatment. Fluorochemical-based barriers (PFAS) were historically used for grease resistance, but these are being phased out under EU PFAS restrictions. Alternatives include PLA coatings, silicone-free dispersion barriers, and clay-composite treatments.

Coated papers

Paper cups and single-use plates typically carry a thin polymer coating — often PE or PLA — to prevent liquid absorption. PE-coated paper is recyclable only in facilities equipped to separate the layers, and is generally not compostable. PLA-coated paper is industrially compostable if the PLA layer is thin enough to meet EN 13432 disintegration criteria.

Starch-based and agri-waste materials

Thermoplastic starch (TPS) — produced by plasticizing native starch with water, glycerol, or other agents — is used in loose-fill packaging, films, and injection-moulded trays. TPS is fully biodegradable and compostable, but is hygroscopic and loses dimensional stability at high humidity. Blending with PHA or PLA improves moisture resistance.

Agri-waste substrates — including bagasse (sugarcane fibre residue), wheat straw, and rice husk — are used in moulded packaging as drop-in replacements for conventional pulp. Bagasse-based containers are widely used in food service and are certified to EN 13432 by several manufacturers.

Material selection considerations

The choice of biodegradable material for a given packaging application depends on several intersecting factors:

End-of-life infrastructure: If industrial composting is not accessible in the target market, materials requiring controlled composting offer no practical end-of-life advantage over conventional plastics.
Food contact compliance: All food contact packaging in Poland must meet Regulation (EC) No 1935/2004 and relevant specific measures. Not all biopolymers have approved food contact status; verification with the supplier is essential.
Migration testing: PLA and PHA at elevated temperatures may exhibit migration above limits. Testing under conditions representative of end use is required.
Labelling claims: EU Directive 2005/29/EC (Unfair Commercial Practices) and the forthcoming Green Claims Directive restrict unsubstantiated environmental claims. Labels must be accurate, specific, and substantiated by recognised standards.