One-step biphasic NADES extraction of phenolics and carotenoids from tomato peels with integrated life cycle assessment

What if the key to unlocking tomato peels' hidden treasure lies in a two-phase liquid system made of natural compounds? This new approach extracts both phenolics and carotenoids in one step—and it's kinder to the planet.

Tomato peels are often discarded, yet they hold a wealth of valuable bioactive compounds. A recent study developed a clever biphasic system using two natural deep eutectic solvents (NADES): choline chloride:urea (ChUr) and menthol:thymol (MenThy). This setup allows simultaneous extraction and separation of phenolics and carotenoids—no harsh chemicals needed.

In sequential extractions, ChUr recovered 198 μg/gDW of phenolics, mainly 4-hydroxybenzoic acid and 4-hydroxybenzaldehyde. Meanwhile, MenThy extracted 601 μg/gDW of carotenoids, including lycopene and β-carotene, plus a portion of flavonoids like quercetin (94 μg/gDW) and naringenin (50 μg/gDW).

By combining both solvents in a 1:1 (v/v) biphasic system, the researchers achieved a 40% increase in phenolic extraction. Interestingly, partial phase separation occurred: 26% of quercetin and 9% of naringenin remained in the MenThy phase. This suggests that careful tuning of solvent ratios can direct where each compound ends up.

The study also integrated a life cycle assessment (LCA), highlighting the environmental benefits of this green extraction approach. With such efficiency and sustainability, this method could transform how we valorize food waste.

Key Points

• Biphasic NADES system extracts phenolics and carotenoids in one step
• 40% increase in phenolic extraction with combined solvents
• Life cycle assessment shows environmental benefits