Implementation of subcritical water extraction with natural deep eutectic solvents for sustainable extraction of phenolic compounds from winemaking by-products

What happens when you combine pressurised water and green designer solvents to rescue valuable treasures from winery waste? Researchers have unlocked a sustainable way to squeeze hidden wealth from leftover grape pomace.

Winemaking leaves behind massive amounts of by-products, but these leftovers are actually packed with valuable phenolic compounds waiting to be rescued. To capture them sustainably, scientists tested a novel method merging subcritical water extraction with emerging eco-solvents known as natural deep eutectic solvents, or NADESs. After screening various options, a blend featuring choline chloride and urea, designated as ChClU, emerged as the top candidate. Because pure NADESs are quite viscous under pressure, researchers cleverly deployed ChClU as a 30 percent solvent modifier rather than a standalone liquid. Temperature control proved vital. Operating at a precise 100 degrees Celsius maximized phenolic recovery while avoiding thermal degradation and unwanted Maillard compounds that form at higher heats. Compared to using subcritical water alone, adding this 30 percent NADES boost significantly increased total extracted phenolic yields. Specifically, the recovery of health-associated compounds like catechin and epicatechin jumped by an impressive 45.05 and 47.98 percent respectively. This pioneering approach establishes a powerful, highly efficient, and genuinely eco-friendly blueprint for transforming winery waste into valuable resources.

Key Points

• Combined subcritical water with 30% ChClU NADES modifier
• Optimum extraction temperature established at 100 degrees Celsius
• Catechin and epicatechin extraction increased by over 45%