Seaweed-based packaging represents one of the most radical departures from conventional packaging thinking. Rather than designing packaging to be recycled or composted after use, seaweed films can be eaten, dissolved in water, or composted at home — eliminating the end-of-life problem entirely. While still at an earlier stage of commercialisation than other innovations in this series, seaweed packaging is attracting significant investment and research attention.
The science
Seaweed-based films are primarily derived from two polysaccharides: alginate (from brown seaweed) and carrageenan (from red seaweed). These naturally occurring polymers can be processed into thin, flexible films with properties suitable for food-contact applications. Alginate films provide good oxygen barrier properties, while carrageenan offers moisture resistance. Blending the two, or combining them with other biopolymers, allows films to be tailored for specific applications.
The films are inherently biodegradable, compostable, and in many formulations edible and water-soluble. They contain no synthetic chemicals and can be produced without petroleum-based inputs. Seaweed cultivation itself is environmentally beneficial: it requires no freshwater, no fertiliser, no arable land, and absorbs CO₂ as it grows.
Companies and products
- Notpla (UK): London-based startup producing Ooho (edible water capsules), seaweed-lined takeaway boxes used at events including the London Marathon, and compostable food packaging. Received the Earthshot Prize in 2022. Series A funding of £20 million.
- Xampla (UK): Cambridge spin-out using plant proteins (primarily pea protein) combined with seaweed-derived materials to create flexible film sachets and coatings. Targeting single-use sachets for condiments, personal care, and laundry products. Listed in the FuturePack directory.
- Kelpi (UK): Welsh startup developing seaweed-based flexible packaging for food and fashion industries. Uses kelp to produce films and rigid containers. B Corp certified.
- Sway (US): Develops seaweed-based alternatives to thin-film plastic packaging. Focus on polybags used in fashion and e-commerce.
Current limitations
Seaweed packaging faces several challenges that limit mainstream adoption:
- Moisture sensitivity: films can soften or dissolve when exposed to water, which limits applications for wet or chilled products
- Mechanical strength: current films are less strong than conventional plastic films, restricting use in high-stress applications
- Shelf life: seaweed films may have shorter shelf life than plastic equivalents, particularly in humid conditions
- Scale: production volumes are still small compared to conventional packaging materials, meaning costs are higher
- Consumer acceptance: the concept of edible packaging requires consumer education and may face resistance in some markets
Outlook
Seaweed packaging is unlikely to replace conventional packaging across broad applications in the near term, but it has clear potential in specific niches: single-serve condiment sachets, event catering packaging, premium food service, and applications where compostability with food waste is desired. As the UK’s food waste collection infrastructure expands under Simpler Recycling, dissolvable and compostable seaweed packaging could find a natural disposal route alongside organic waste.