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A cellulose-based titanium dioxide alternative inspired by nature

Article-A cellulose-based titanium dioxide alternative inspired by nature

© AdobeStock/wiltonmitsuo Eucalyptus trees for wood, cellulose and medicinal
Inspired by the bright white Cyphochilus beetle, UK startup Impossible Materials has developed a natural alternative to titanium dioxide using cellulose-based microparticles.

Europe’s recent moves to ban the use of food grade Titanium Dioxide (TiO2), coupled with consumer preferences for natural and renewable ingredients, has led manufacturers to consider alternatives to this compound.

Traditionally used as a food additive in pastries, soups and sauces, its links to cancer in particular, has led Cambridge University spin-out Impossible Materials to develop a cellulose-based, TiO2 alternative.

The key here is the use of cellulose itself, which is the main component in every plant cell, and is already used in food products, often as a thickener. It can also be sourced from waste material, such as wood pulp or agricultural waste.

“We developed a 100% plant-based white pigment from cellulose,” explains Dr Lukas Schertel, Impossible Materials’ CEO & Co-founder.

“Cellulose is safe - not nano sizes which is at the source of the problem with TiO2-, it is widely available, which allows us to scale it at a competitive price, and truly renewable.

“Our focus is not only on making a safer product but also contributing to a circular economy through innovative processing.”

Cyphochilus beetle

The inspiration behind the work is the bright white Cyphochilus beetle, specifically the thin layer of scales on its exoskeleton, which scatters all wavelengths of light making these beetles shine a brilliant white.

These non-uniform scales are made up of a rough, porous structure that enable light to bounce or reflect, maximising light scattering and contributing to the vibrant white colour.

As their research states: “By tuning the size of such cellulose-based microparticles (CMPs), scattering performances can be optimised on the single scatter level.

“Moreover, by additionally controlling the spatial arrangement of these particles in a disordered network, both highly scattering and optical haze materials can be produced, outperforming current materials.”

Dr Schertel, working alongside colleagues from the University of Cambridge, identified the creation of the white colour from an extremely thin scale as the main challenge.

He said: “(CMP) particles that are very long or with a very small diameter would have a decreased scattering efficiency, as in the case of other cellulose nanomaterials.”

The team also point out CMPs’ safety aspects such as non-cytotoxicity and the fact that they are much larger than regular cellulose nanofibers and nanocrystals.

This means they can be compared to microcrystalline cellulose, which has been approved for many applications in the food and pharma sectors.

© AdobeStock/DyrElenaHeap of white chocolate cubes with dangerous additive e171-free label

Titanium dioxide safety: Bans and directives

Dr Schertel believes the material taps into current food trends that promote a cleaner approach to food production, characterised by a ‘greener’ mindset adopted by consumers.

“We see two drivers for the material in the market. The environmental awareness of customers and businesses to use natural and renewable ingredients and the current regulatory pressure around TiO2 in food.”

In June 2021, the European Food Safety Authority (EFSA) declared that TiO2 was no longer deemed safe when applied as a food additive.

A handful of member states have taken action prior to this decision having either banned or restricted TiO2 use over the past few years.

France has suspended its use since January 2020, in the wake of opinions issued by the country’s food agency in 2017 and 2019.

However, the UK still allows the use of TiO2, with no indications that it will get on board with the EU on this issue. The country’s Committee on Toxicity has published an interim position paper outlining its reasoning.

As it is a ‘regulation’ rather than a ‘directive,’ the ruling takes immediate effect and does not have to be transposed into national law by individual Member States.

Good material performance in wet & dry applications

“We’ve had enormous interest in the application of our material,” says Dr Schertel.

“Over 60 companies have reached out. We are under pressure to scale our production to deliver enough material. This is why Impossible Materials is currently raising funds with investors.”

“We are constantly scaling the material production. We are still an early-stage start-up, working with selected customers,” Dr Schertel adds.

“It is worth mentioning, that these are industry giants in the health-sectors. We have shown the material performance in wet and dry applications and can deliver powders and slurry.”