From Waste to Resource: Exploring Green Approaches for Phenolics Recovery from Olive Leaves

What if olive leaves, a waste product of the agri-food industry, could be turned into a treasure trove of health-boosting compounds—using nothing but green chemistry?

Olive leaves are often discarded, but they hide a valuable secret: phenolics, natural antioxidants with big potential. The challenge? Extracting them without harming the planet. This study pits conventional solvents against a new generation of green solvents called NADES—natural deep eutectic solvents—using two scalable methods: solid–liquid extraction with stirring and microwave-assisted extraction.

The results are striking. NADES, especially a choline–glycerol mix, outperformed traditional solvents, pulling out more polyphenols and showing stronger antioxidant activity. When paired with microwaves, this green duo delivered higher yields in less time, proving that sustainability doesn't mean sacrificing efficiency.

But there's a trade-off. Conventional methods using water or ethanol/water mixtures needed longer times or higher temperatures to match NADES performance, yet they offer easier scalability for industry. The choice isn't simple—it's a balancing act between greenness, speed, and practicality.

This research lights a path toward circular economy, where waste becomes resource, and chemistry becomes kinder to our planet.

Key Points

• NADES outperform conventional solvents for polyphenol extraction.
• Choline–glycerol NADES + microwaves = highest efficiency.
• Conventional methods need more time or heat, but scale easier.