Sugar-based bioplastic to sweeten packaging

Reasearchers from Imperial College, London, said the polymer could be used in a range of applications including food packaging.

The degradable polymer, made from sugars known as lignocellulosic biomass, has many of the qualities of leading bioplastic material polylactide, but degrades more quickly and at lower temperatures, Dr Charlotte Williams told FoodProductionDaily.com.

Key breakthrough​

“Our key breakthrough was in finding a way of using a non-food crop to form a polymer, as there are ethical issues around using food sources in this way,”​ said project leader Williams.

Current bio-renewable plastics use crops such as corn or sugar beet and are usually manufactured through fermentation. The new polymer, however, is produced by a lower energy chemical process. The team has spent some time developing a production technique to allow the polymer to become commercially viable.

“For the plastic to be useful it had to be manufactured in large volumes, which was technically challenging,”​ said Williams. “It took three-and-a-half years for us to hit a yield of around 80 per cent in a low energy, low water use process. This means that 100g of glucose could typically yield around 70g of the plastic.”​

The team said this is significant as polylactide is formed in a high energy process requiring large volumes of water. In addition, when it reaches the end of its life polylactide must be degraded in a high-temperature industrial facility.

By contrast, the oxygen-rich sugars in the new polymer allow it to absorb water and degrade to harmless products at between temperatures of 40-70°C depending on the level of glucose in the polymer’s repeatable unit. This means that the material could degrade at temperatures found in domestic compost heaps, said Williams.

The substance has a degradation time of a few months to one year, compared to polylactide’s three months to two years, she added.

Commercialisation​

The team is currently working on scaling up production and is scheduled to go to the pilot plant stage – which would see output jump from kilogrammes to tons – by the end of the summer. Securing food contact authorisation is also an issue the group said it will soon begin to address.

“The development of the material is very promising and I’m optimistic that the technology could be in use within two to five years,”​ said Williams, who is already working with a number of commercial partners and is keen to engage others interested in the material.

Biorenewable plastics are materials whose feedstock material (monomer) comes from renewable resources. The leading example is polylactic acid which derives from lactic acid, produced by fermentation of corn or sugar beet. These biorenewable plastics are different to biopolymers, which are naturally occurring polymers such as starch or cellulose.