Temperature-responsive deep eutectic solvents: A green and recyclable extractant for efficient extraction of natural bioactive compounds

Imagine a sweetener that's not only natural and low-calorie but also extracted using a green, reusable solvent—this is the promise of rubusoside from a Chinese raspberry relative.

Rubusoside, the sweet powerhouse in Rubus chingii var. suavissimus, offers high sweetness with few calories and a safe profile—perfect for natural sweeteners and functional foods. Yet, efficient green extraction methods have lagged behind. Now, scientists have crafted a microwave-assisted deep eutectic solvent (DES) system that changes the game.

The winning formula? A ternary DES of choline chloride, 1,2-propylene glycol, and 1,3-butanediol (1:2:2), which outperformed plain water extraction. By fine-tuning conditions—33% moisture, a liquid-solid ratio of 21 mL/g, 6 minutes, and 320 W—they achieved a 7.89% rubusoside yield.

What's the secret? Advanced analyses revealed non-covalent interactions, like hydrogen bonds and van der Waals forces, between the DES and rubusoside. Meanwhile, electron microscopy showed the DES and microwaves working together to break down plant tissues, boosting mass transfer. After extraction, a resin separated the rubusoside, and the DES was reused five times without losing its mojo.

This isn't just a method; it's a blueprint for sustainable, efficient extraction—proving that green chemistry can be both powerful and kind to the planet.

Key Points

• Ternary DES outperforms microwave water extraction for rubusoside.
• Optimal conditions yield 7.89% rubusoside in 6 minutes.
• DES remains stable after five reuse cycles.