Breaking polyphenol–polysaccharide interactions: the promising role of natural deep eutectic solvents

What if tomato peels—usually tossed aside—could be transformed into a treasure trove of health-boosting compounds using nothing but eco-friendly solvents?

Tomato peels, a common food waste, hide valuable phenolics and carotenoids—antioxidants with big health potential. But extracting them efficiently has been tricky. Now, scientists have turned to Natural Deep Eutectic Solvents (NADES), a new class of green solvents, to unlock these compounds in a single, elegant step.

The team designed a biphasic system using two NADES: choline chloride:urea (ChUr) and menthol:thymol (MenThy). In sequential extractions, ChUr recovered 198 μg/gDW of phenolics, mainly 4-hydroxybenzoic acid and 4-hydroxybenzaldehyde. MenThy pulled out 601 μg/gDW of carotenoids (lycopene and β-carotene), plus flavonoids like quercetin (94 μg/gDW) and naringenin (50 μg/gDW).

When combined in a 1:1 (v/v) biphasic setup, phenolic extraction jumped by 40%. Even better, partial phase separation occurred: 26% of quercetin and 9% of naringenin stayed in the MenThy phase, while phenolics concentrated in ChUr. This clever partitioning simplifies purification.

With integrated life cycle assessment, the study ensures environmental benefits are real, not just theoretical. This is a promising step toward sustainable, efficient extraction of bioactive compounds from agricultural waste.

Key Points

• Biphasic NADES boosts phenolic extraction by 40%
• ChUr recovers phenolics; MenThy extracts carotenoids
• Integrated life cycle assessment confirms sustainability