Prawn shells, orange peels and apple cores get tossed into the bin every day without a second thought.
But scientists here have found a way to turn them into chitin, a biopolymer that can be made into food-grade packaging, using an organic process.
The biodegradable packaging material could kill two birds with one stone; since it could potentially replace plastic containers used for food takeaways, it would help Singapore reduce its single-use plastic waste.
Plastic and food accounted for about 40% of the Republic’s total amount of waste last year (2019).
In a process devised by a team from Nanyang Technological University’s food science and technology (FST) programme, food waste is converted into chitin without using chemicals, said Professor William Chen, the Michael Fam chair professor, FST director and principal project investigator.
Prawn shells are first removed and placed in a flask of water together with some fruit waste, such as grape skin, to ferment the shell. After 24 hours, the water starts to turn turbid when microbes start growing in the solution. Fermentation removes minerals and protein residue from the shells.
The mixture is then filtered and the shells are dried in an oven to remove all moisture. Afterwards, they are ground into powder.
The resultant material is chitin, a naturally occurring biopolymer found in fungi and the exoskeleton of some animals.
In a separate process, chitin can be converted into chitosan by adding alkalis, such as sodium hydroxide. The solution is then put in a mould and dried to form a thin packaging film that can be used to pack food.
The team, whose research findings were published in the peer-reviewed journal AMB Express in January, is in talks with restaurants to commercialise the process.
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Source: The Straits Times, 10 May 2020