SINGAPORE: Researchers from the National University of Singapore (NUS) have found a way to turn the shells of crustaceans, as well as discarded branches, into nutritional supplements and medicine.
This novel process can turn prawn and crab shells into L-DOPA, a widely used drug to treat Parkinson’s disease, NUS said in a press release on Thursday (Oct 29).
A similar method can be used to convert wood waste into 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 to reduce reliance on the use of non-renewable fossil fuels and energy-consuming processes, said NUS.
Waste such as prawn shells and branches pruned from trees usually end up in landfills.
The global food processing industry generates as much as 8 million tonnes of crustacean shell waste annually, said NUS. Last year, Singapore also generated more than 438,000 tonnes of wood waste. This includes branches pruned from trees and sawdust from workshops.
Deriving ways to upcycle these food and agricultural waste materials into useful compounds will reap benefits without straining landfills.
“Although reusing waste materials has gained traction in recent years, the typical output of chemicals produced from waste recycling is often less diversified than the conventional chemical synthesis pipeline which uses crude oil or gas.
“To overcome the limitations, the NUS researchers came up with a pathway that marries a chemical approach with a biological process,” said the university.
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 converted them into a substance that can be “digested” by microbes.
The second step involved a biological process, similar to the fermentation of grapes into 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.
PRODUCING ORGANIC CHEMICALS CHEAPER AND FASTER
L-DOPA is conventionally produced from L-tyrosine, a chemical made from fermenting sugars. NUS said the yield produced by their method using crustacean waste is similar to that achieved in the traditional method using 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 common sugar used in the conventional production method, costs between US$400 to US$600 per tonne while shrimp waste costs only about US$100 per tonne.
Meanwhile, proline is conventionally produced through pure biological processes. NUS said their team’s method replaced most of the transformations by 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 rapid and can utilise a variety of harsh conditions to break down a wide variety of waste materials as no living organisms are involved, it can only produce simple substances.
On the other hand, biological processes are a lot slower and require very specific conditions for the microbes to flourish, but can produce complex substances which tend to be of higher value.
“By combining both chemical and biological processes, we can reap the benefits of both to create high value materials,” said Asst Prof Zhou.
POTENTIAL TO UPCYCLE OTHER TYPES OF WASTE
NUS said their team’s methodology has the potential to be applied to different types of waste materials. This process can also be tailored based on the type of waste as well as the target end product.
Moving forward, NUS said the team is looking to adapt their unique process to other forms of waste, such as carbon dioxide and waste paper.
This would reduce reliance on non-renewable resources for acquiring chemicals which are important constituents of many nutritional supplements and medicine, NUS added.
"Given that these chemicals are found in a vast array 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, locally available substrates found in Singapore,” shared Assoc Prof Yan.
The research team is also planning to scale up the processes currently developed in their laboratories and to work with industrial partners to commercialise this technology.