Selective bioactive compound extraction from fennel seeds (Foeniculum vulgare) using subcritical water extraction: A comparison with green extraction technologies

What if the secret to a sweeter, healthier future lies hidden in a humble berry? Scientists have unlocked a green, recyclable method to extract a natural sweetener, and it's powered by chemistry that mimics nature's own elegance.

Deep inside the leaves of a Chinese berry plant, Rubus chingii, hides a molecule with a bright future: rubusoside. This compound is intensely sweet, low in calories, and safe—making it a dream candidate for natural sweeteners and functional foods. But getting it out of the plant has always been a challenge. Traditional methods are often inefficient and far from green. Now, researchers have developed a smarter, cleaner way to do it, using a special blend of natural solvents and microwave energy.

The secret weapon is a ternary deep eutectic solvent (DES)—a mixture of choline chloride, 1,2-propylene glycol, and 1,3-butanediol. This combination outperformed plain water extraction, achieving a rubusoside yield of 7.89% under optimal conditions: 33% moisture, a liquid-to-solid ratio of 21 mL/g, just 6 minutes, and 320 watts of power. The team used advanced techniques like infrared spectroscopy and quantum chemistry models to show that the DES forms strong non-covalent bonds with rubusoside, gently pulling it out of the plant matrix.

What's more, the DES and microwaves work together to physically disrupt plant tissues, making extraction faster and more efficient. After extraction, a simple resin (LX-28) can separate the rubusoside, and the DES can be reused at least five times without losing performance. This isn't just a lab trick—it's a sustainable, scalable strategy that could transform how we produce natural sweeteners. The future of sweetness just got a little greener.

Key Points

• Ternary DES (choline chloride, 1,2-propylene glycol, 1,3-butanediol) outperforms water extraction.
• Optimal yield: 7.89% rubusoside under 33% moisture, 21 mL/g, 6 min, 320 W.
• DES is reusable for 5 cycles; green, efficient, and recyclable.