Natural Deep Eutectic Solvents in Biorefineries: Bridging Sustainability and Efficiency

Why We Need Cleaner, Greener Solutions

The growing environmental concerns surrounding traditional industrial processes have catalysed a shift towards more sustainable and circular practices. The traditional reliance on non-renewable resources and the generation of significant waste streams have prompted researchers and industry leaders to seek alternatives that minimize environmental footprints while maximizing resource efficiency. In this context, bio refineries emerge as a promising solution. Bio refineries are facilities that transform natural, renewable materials like plants, algae, or even food and fish waste into valuable products such as biofuels, bioplastics, cosmetics, or nutritional supplements.

But even bio refineries need to find greener ways to extract these compounds from biomass. The efficiency and sustainability of bio refinery processes heavily depend on the solvents used for extraction and processing of such compounds being these solvents often toxic, volatile, and non-biodegradable.

What Are NADES — and Why Are They Game Changers?

Natural Deep Eutectic Solvents (NADES) have emerged as a promising class of “green” solvents with the potential to revolutionize extraction processes in bio refineries. NADES are solvents made by mixing two or more natural ingredients — for example, sugars like glucose, amino acids like proline, or organic acids like citric acid. NADES are characterized by their eco-friendly nature, as they are often derived from natural and renewable sources (Usmani et al., 2023). Moreover, the properties of NADES, including viscosity, polarity, and pH, can be fine-tuned by adjusting factors such as water content, temperature, and the ratio of components. This adaptability allows for the optimization of NADES for specific applications, making them versatile tools in bio refinery processes.

In simple terms, NADES are like "natural chemical cocktails" that can replace harmful industrial solvents. You can even think of them as eco-friendly liquids that help break open plant or animal cells to release oils, proteins, and other valuable compounds.

NADES have demonstrated remarkable potential in the extraction of bioactives from a variety of biomass sources. These solvents can effectively extract a wide range of bioactives, such as phenolics, alkaloids, terpenoids, polysaccharides, lipids, and peptides, which are valuable for their antioxidant, antimicrobial, and therapeutic properties (Huang et al., 2025).

What Makes NADES Better Than Traditional Solvents?

One of the primary advantages of NADES over traditional solvents is their environmental compatibility. Unlike many organic solvents, NADES are non-flammable and typically exhibit low volatility, reducing the risk of atmospheric pollution. Additionally, their low toxicity and high biodegradability make them attractive options for applications in food and pharmaceutical industries, where safety is paramount (Huang et al., 2025). NADES also offer enhanced extraction efficiency due to their ability to disrupt cell walls and membranes, facilitating the release of intracellular components (Villa et al., 2024). This property is particularly beneficial for extracting bioactives from plant materials, where conventional solvents may struggle to penetrate complex cellular structures. Furthermore, NADES can be tailored to selectively extract specific compounds, improving the yield and purity of target bioactives.

Real Example: NADES in the VALORISH Project

Within the VALORISH project, NADES are being explored for their ability to extract oil fractions and bioactive compounds from fish by-products. Our partner, ANFACO, is evaluating fish oil extraction using several emerging techniques—including NADES, supercritical CO₂ (scCO₂), and subcritical solvent extraction (SSE)—and comparing them to traditional wet rendering methods. Experiments involve different combinations of NADES made from sugars (e.g., glucose, fructose, sorbitol), organic acids (e.g., citric, oxalic, malic, tartaric acids), amino acids (e.g., proline, ornithine, arginine, citrulline), choline chloride, and water, under varying conditions. Researchers then evaluate the extraction performance is assessed by analysing different parameters such as oil yield, fatty acid composition, acid value, and peroxide index. The ultimate goal? To find the most sustainable and energy-efficient method to recover valuable compounds—turning waste into worth without compromising on quality.

References

Huang, M. M., Yiin, C. L., Chin, B. L. F., Lock, S. S. M., Othman, I., Ahmad Zauzi, N. S. B., & Chan, Y. H. (2025). Natural deep eutectic solvents (NADES) for sustainable extraction of bioactive compounds from medicinal plants: Recent advances, challenges, and future directions. Journal of Molecular Liquids, 425, 127202. https://doi.org/10.1016/j.molliq.2025.127202

Usmani, Z., Sharma, M., Tripathi, M., Lukk, T., Karpichev, Y., Gathergood, N., Singh, B. N., Thakur, V. K., Tabatabaei, M., & Gupta, V. K. (2023). Biobased natural deep eutectic system as versatile solvents: Structure, interaction and advanced applications. Science of The Total Environment, 881, 163002. https://doi.org/10.1016/j.scitotenv.2023.163002

Villa, C., Caviglia, D., Robustelli della Cuna, F. S., Zuccari, G., & Russo, E. (2024). NaDES application in cosmetic and pharmaceutical fields: An overview. Gels, 10(2), 107. https://doi.org/10.3390/gels10020107