The corn-starch bottles are made from a type of plastic called polylactic acid (PLA). The bottles were launched in May this year, with Belu informing users that the bottles could be commercially composted back to soil in 12 weeks.
Trelawney Dampney, chairman of the Composting Association and managing director of a composting business in Dorset, said companies like his would not risk leaving any bottle in their compost.
He said: "If we get a batch of garden waste in with bottles included they will be shifted out, we will not sort through to pick out biodegradable ones – we couldn't afford that. The only way it would work is if all households in the UK had a compost bin and on the bottle it is very very clearly marked as biodegradable."
2) What happens when it is mixed with regular PET bottles?
Another concern is that if the Belu plastic bottles end up among other recyclable forms of plastic, they can damage the resulting product. Belu says on its website: "As long as bio-bottles make up less than 1% of all plastics they won’t affect the quality of recycled products."
But this was not the view from the plastics recycling sector. Paul Davidson, plastics technical manager at the Waste and Resources Action Programme (WRAP), explained: "You don't need too much PLA to mess PET up, especially if you want to recycle it back into a bottle. It will only take a few percent of PLA to make PET non-viable and that is just another concern for plastic reprocessors to deal with."
Long term, we all agree that corn-based biodegradable packaging is a great thing.
Mr Paget [founder of Belu] claimed there would be an inevitable move towards corn starch bottles such as that produced by Belu and suggested it was "short sighted" not to prepare for such a situation.
"Plastic comes from petrol, a non-renewable source," he explained. "To base production on a material that is soon to run out is very short sighted. We need to look at the supply, what will be around in the future? This is a medium to long-term project."
Mr Pagent said his long-term goal was to see all food packaging made out of biodegradable material.
He said: "Wouldn't it make sense if all packaging was made from a compostable polymer? If a supermarket had to throw out unsold food it could send the food and the packaging straight to compost. You would cut down on labour and avoid landfill – it is win win win."