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SINGAPORE: Researchers at the National University of Singapore (NUS) have found a way to turn crustacean shells, as well as discarded branches, into nutritional supplements and medicines.
This new process can convert shrimp and crab shells into L-DOPA, a drug widely used to treat Parkinson’s disease, NUS said in a press release on Thursday (October 29).
A similar method can be used to convert wood waste to proline, which is essential for the formation of healthy collagen and cartilage.
Not only can this process save time and lower production costs, it also helps reduce dependence on non-renewable fossil fuel use and energy-consuming processes, NUS said.
Waste such as shrimp shells and pruned tree branches often end up in landfills.
The global food processing industry generates up to 8 million tonnes of shellfish waste annually, NUS said. Last year, Singapore also generated more than 438,000 tonnes of wood waste. This includes pruned tree limbs and shop sawdust.
Deriving ways to recycle these food and agricultural waste materials into useful composites will pay off without forcing landfills.
“Although the reuse of waste materials has gained ground in recent years, the typical production of chemicals produced from recycling waste is often less diversified than conventional chemical synthesis pipeline that uses crude oil or gas.
“To overcome the limitations, the NUS researchers devised a pathway that combines a chemical approach with a biological process,” the university said.
The research team led by Associate Professor Yan Ning (left) and Assistant Professor Zhou Kang developed an integrated recycling process to produce high-value amino acids from waste materials. (Photo: National University of Singapore)
The NUS team, led by Associate Professor Yan Ning and Assistant Professor Zhou Kang from the Department of Chemical and Biomolecular Engineering, took four years to derive their method.
The researchers first applied chemical processes to the waste materials and turned them into a substance that microbes can “digest.”
The second step involved a biological process, similar to the fermentation of grapes in wine, where they engineered special strains of bacteria such as Escherichia coli to convert the substance produced in the chemical process into a higher value product such as amino acids.
CHEAPER AND FASTER PRODUCTION OF ORGANIC CHEMICALS
L-DOPA is conventionally produced from L-tyrosine, a chemical made from fermented sugars. NUS said that the yield produced by its method that uses shellfish waste is similar to that obtained with the traditional method that uses sugars.
NUS said their method also has the potential to provide L-DOPA at a lower cost given the abundance and low cost of shell waste.
Glucose, which is the most commonly used sugar in the conventional production method, costs between US $ 400-600 per ton, while shrimp waste costs only around US $ 100 per ton.
Meanwhile, proline is produced conventionally by pure biological processes. NUS said his team’s method replaced most of the transformations using chemical processes, which are much faster.
“As a result, the new integrated process could achieve higher productivity and potentially lead to reductions in capital investment and operating costs,” added NUS.
Although chemical processes are fast and can use a variety of harsh conditions to break down a wide variety of waste materials, as there are no living organisms involved, they can only produce simple substances.
On the other hand, biological processes are much slower and require very specific conditions for microbes to thrive, but they can produce complex substances that tend to be of higher value.
“By combining chemical and biological processes, we can reap the benefits of both to create high-value materials,” said Asst Prof Zhou.
POTENTIAL TO SUPPLEMENT OTHER TYPES OF WASTE
NUS said his team’s methodology has the potential to be applied to different types of waste materials. This process can also be adapted depending on the type of waste and the final destination product.
Going forward, NUS said the team is looking to adapt its unique process to other forms of waste, such as carbon dioxide and used paper.
This would reduce dependence on non-renewable resources to purchase chemicals that are important components of many nutritional supplements and medications, NUS added.
“Since these chemicals are found in a wide range of commercially valuable pharmaceuticals, pigments and nutrients, we are excited to expand our research and develop new methodologies to produce value-added chemicals from other abundant and locally available substrates in Singapore, “shared Associate Professor Yan.
The research team also plans to expand the processes currently being developed in its laboratories and work with industrial partners to commercialize this technology.
