Published on 31 Aug 2023

Turning Kale Waste Into Treasure - Professor Hu Xiao

We are delighted to share that Professor Hu Xiao, Programme Director of Sustainable Chemistry & Materials at the Nanyang Environment & Water Research Institute (NEWRI), and his team have been featured on various media platforms. Their technique for converting kale waste into valuable ingredients for health and personal care products has garnered widespread attention for its potential to reduce food waste and emissions.

Phytochemicals, which can be found in plants, have long been known for its ability to protect our cells from damage. These natural compounds are commonly used in consumer products such as supplements and beauty products. However, the existing processes for extracting phytochemicals from kale are not only energy-intensive but also contribute to CO2 emissions. Furthermore, these processes can only extract one type of phytochemical at a time.

In their quest to create a sustainable and efficient solution for transforming vegetable waste into valuable resources, Prof Hu and his team turned to natural deep eutectic solvents (NADES). These non-toxic liquids, composed of plant-based compounds like amino acids, sugars, and vegetable oil by-products, were mixed with processed kale waste to observe the reactions between molecules. Through meticulous testing, the team discovered that when the mixture was stirred and left to settle, it naturally separated into layers, enabling the easy extraction of phytochemicals such as polyphenols, carotenoids, and chlorophylls from kale – all without the need for high temperatures or pressure.

"The use of non-toxic and naturally derived solvents in our method makes it a food-safe technique. At the same time, our method preserves the potency of the extracted active ingredients, making it highly attractive for industry adoption. The extracted nutrients can potentially be used for applications in personal care products, cosmetics, food supplements, and herbal extracts."
- Professor Hu Xiao - 

Dr Liang Yen Nan (left) and Professor Hu Xiao (right) of NEWRI showcasing their sustainable and innovative technique of converting kale waste into valuable ingredients for health and personal care products. (Source: NTU)

The team's research work has been published in the peer-reviewed journal, Separation and Purification Technology, titled "Single-step extraction of bioactive compounds from cruciferous vegetable (kale) waste using natural deep eutectic solvents" (DOI:

The team has also filed a patent for this innovative technique in Singapore.

For the complete media release, please visit the following link: Turning kale waste into treasure | NTU Singapore

Congratulations to Professor Hu Xiao and his team on their achievement!

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