Rethinking Waste: A Mission to Turn Onion Skins into the Future of Packaging

What if the stuff we call waste wasn’t just a byproduct, but also a design flaw?

Written by Aastha Kothari

EDITED by ARIYANA RAYATT

20 JUNE 2025

With the growing urgency of the global plastic crisis, it’s clear that swapping petroleum-based plastics for compostable alternatives isn’t enough. A new opportunity lies in rethinking how we design materials in the first place; in a way that they work with, not against, biological systems. This shift is sparking a new era of innovation, one where waste is no longer the end of the line, but the beginning of a new value cycle. Among the innovators is HUID, a Scotland-based biotech startup founded by Renuka Ramanujam, with Chief Scientific Officer Marie Rapin leading the tech development. The company is transforming onion skins into compostable, sustainable packaging.  

But this is more than just a startup story. HUID’s work is a window into what the next chapter of biomaterials might look like, what it would mean to rethink material value, innovation strategy and the role of biology in solving industrial problems.

The Plastic Crisis is a Design Crisis

 

Plastic was designed to last. That is the problem. Each year, the world produces 400 million tons of plastic waste, with over a third of it used for packaging, most of which is used once and discarded. Despite the recycling rhetoric, less than 9% of that plastic is getting recycled. The rest clogs landfills, pollutes oceans, and even contaminates our food, water and bodies. 

At the same time, the food industry generates 1.3 billion tons of waste annually, much of it from plant parts discarded before they ever reach shelves or tables. This includes fibrous plant parts like onion skins, corn husks, and banana peels: materials with complex structures and hidden functional potential.

What if these two crises, plastic pollution and food waste, aren’t separate, but symptoms of the same flawed system?”
It’s a question that drives HUID’s design philosophy, and one that Marie Rapin sees at the heart of the problem. To her, this isn’t just a materials issue. It’s a systems design failure.

Rapin sees agricultural waste as an untapped resource. One that offers organic materials with structural strength and untapped potential. – “We don’t need to cut down trees. We don’t need to grow new crops. The raw material already exists—we just need to transform it,” Rapin says.

The Hidden Materials in Plain Sight

HUID’s work centres around one question: What if food waste can become biodegradable packaging that isn’t just compostable, but helps extend food shelf life? 

At the heart of their innovation is microfibrillated cellulose, a naturally abundant polymer that, when extracted from onion skins, becomes a surprisingly elegant substitute for plastic.

The team at HUID extracts microfibrillated cellulose from onion skins—a faster, more energy-efficient, and cleaner process than traditional wood-based methods. Extracting cellulose from wood requires high temperatures and harsh chemicals like sodium hydroxide or sulfur compounds, which generate toxic wastewater and demand energy-intensive treatment. Onion skins, by contrast, are low in lignin – a structural material found in wood – and easier to break down, allowing extraction at lower temperatures and with milder reagents. The result is a product that is not only biodegradable but also can be mixed with other onion skin extracts to extend the shelf life of food, thanks to the natural microbial and antioxidant properties of the onions. 

Dried onion skins—a fibrous, antioxidant-rich material discarded in bulk by food processors.

Inside the Process: Circular Design in Action

Unlike conventional paper or bioplastics, which often require wood harvesting or energy-intensive production, HUID’s method doesn’t rely on new farming or cutting down trees.

Instead, HUID turns to a material that already exists—and is typically discarded: onion skins. Stripped off in processing plants by the tonne, Rapin explains that these skins are rich in natural strength and beneficial compounds.

The process at HUID is a circular design with low energy processing, no synthetic additives and a material that degrades safely. Their process has been distilled into five carefully designed steps:

  1. Collection – HUID sources onion skins from food processing plants, where they would otherwise be discarded.
  2. Extraction – Using a low-energy process, they extract microfibrillated cellulose,
  3. Formation – The extracted microfibrillated cellulose is mixed with natural binders and pressed into sheets, similar to making paper but without the need for wood pulp.

Two material lines, Pyber sheet and Pyber moulded fibre, are already in small-scale production, with trials underway for real-world applications.  

Microfibrillated cellulose extraction from onion skin
Sample PYBER sheets

Scaling Up: The Challenges of Sustainable Innovation

Like many climate-tech start-ups, HUID’s biggest hurdle isn’t just technical but also industrial. 

“At a small scale, everything works fine. But when you scale up from a few kilos to several tonnes, new technical challenges emerge,” Rapin explains. “It’s not just about making more; it’s about ensuring efficiency and consistency at a much larger scale.”

HUID is currently refining its processes to meet industrial demand. The company has received funding from the National Manufacturing Institute Scotland (NMIS) and is working toward its first large-scale trials in Spain. 

Beyond breaking into the packaging market and displacing cheap, mass-produced plastic, innovation alone won’t be enough. It requires systematic buy-in, especially from brands, regulators and supply chains that shape the market. 

Moulded fibre punnets made from PYBER, offering a compostable alternative to conventional food trays.

The Future of HUID and Sustainable Packaging

For HUID, the answer isn’t to create new resources, but to redesign our relationship with what we already waste. More than a business model, it’s a systems approach to materials. One that sees value not in extraction, but in transformation.

Despite the hurdles, HUID is gaining traction. The company recently secured its first commercial sale, marking a significant step in proving that onion-skin packaging is a viable, scalable alternative. Looking ahead, Rapin sees even greater potential in the material’s chemistry. “Onion skins contain many valuable compounds. We could explore applications in nutraceuticals, textiles, or even food ingredients,” she says. “But as a startup, focus is key. Right now, packaging is our priority.”

That focus is evolving. HUID is developing an advanced bioactive film, an innovation that introduces onion skin’s natural antimicrobial properties directly into the material, further enhancing its ability to preserve food.

Prototype of HUID’s advanced bioactive film, designed to extend food shelf life.

“The next big R&D push is about leveraging bioactives in a way that makes our packaging not just sustainable, but functional,” Rapin adds. It’s another step in HUID’s larger belief: biology already offers the tools. We just need to design with it

A Future Without Waste?

The future of packaging won’t just be about replacing plastic, but rethinking how materials are designed from the start. HUID’s approach puts biology at the centre of that process, using food waste not only as a resource but as part of a new material system. By focusing on transformation rather than extraction, HUID shows how waste can become a foundation for more sustainable supply chains. The company’s recent progress marks a shift from concept to reality, offering packaging that works with nature rather than against it. “There’s still so much to explore,” Rapin says. “The industry is moving, but to truly shift away from plastic, we need solutions that are scalable, cost-effective, and easy to adopt.” HUID’s work is part of a broader change in material innovation—one that treats waste as a resource and biology as core infrastructure, not just a tool of last resort.

"To truly shift away from plastic, we need solutions that are scalable, cost-effective, and easy to adopt.”
Marie Rapin

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