Green Extraction Strategy Using Bio-Based Aqueous Biphasic Systems for Polyphenol Valorization from Grape By-Product.

Area of Science:

• Green Chemistry
• Biochemical Engineering
• Separation Science

Background:

• Polyphenols possess significant antioxidant properties and are abundant in fruit/vegetable waste.
• Current organic solvent extraction methods are inefficient and environmentally taxing.
• Sustainable and cost-effective polyphenol separation techniques are urgently needed.

Purpose of the Study:

• To develop and evaluate ionic liquid-based aqueous biphasic systems (IL-ABSs) for polyphenol separation.
• To investigate the partitioning behavior of model phenolic compounds (resveratrol, quercetin, gallic acid) in IL-ABSs.
• To assess the efficiency of IL-ABSs for polyphenol extraction from grape stem extract.

Main Methods:

• Utilized cholinium-based ionic liquids (ILs) and polypropylene glycol (PPG400) to form aqueous biphasic systems (ABSs).
• Employed model compounds (resveratrol, quercetin, gallic acid) to study partitioning behavior.
• Applied IL-ABSs to extract polyphenols from real-world samples (grape stem extract).

Main Results:

• Resveratrol and quercetin preferentially partitioned into the PPG-rich phase due to hydrophobicity and IL salting-out effects.
• Gallic acid, being hydrophilic, predominantly migrated to the IL-rich phase.
• High extraction efficiencies were achieved: ~99% for resveratrol and 78% for gallic acid from grape stem extract.

Conclusions:

• IL-ABSs provide an efficient and selective method for separating polyphenols.
• This approach offers a sustainable alternative to traditional organic solvent extraction.
• The developed IL-ABSs show significant potential for industrial applications in polyphenol purification.