Glycerol-Based Deep Eutectic Mixtures for Grape Pomace Waste Valorization and Ochratoxin A Degradation

Grape pomace, a major wine industry byproduct, is rich in bioactive compounds and increasingly explored for sustainable valorization. However, lacking proper storage, this matrix may become contaminated with ochratoxin A (OTA), a nephrotoxic and potentially carcinogenic mycotoxin produced by Aspergillus and Penicillium species commonly found in grapes, wine, and their byproducts. This study investigates grape pomace valorization using glycerol-based deep eutectic solvents (DES) as sustainable media for bioactive compound extraction and enzymatic OTA degradation with porcine pancreatic lipase (PPL). DES were synthesized (Glycerol/Sodium acetate (1:1, DES1), Glycerol/Glucose (1:1, DES2; 2:1 DES3), Glycerol/Choline chloride/Urea (1:1:1, DES4), Glycerol/Betaine (1:1, DES5), and Glycerol:Sodium Lactate (1:1, DES6)) and characterized for their physicochemical properties, including their behavior under varying water content. In vitro degradation screening identified DES2 (glycerol:glucose, 1:1) with 90% water as the most effective mixture for OTA degradation, achieving over 90% within 4 h. This DES was subsequently tested for phenolic extraction, showing superior performance to ultrapure water, especially at 25% water. To enhance degradation in the matrix, the grape pomace extract was adjusted to 90% water and pH-corrected. This strategy enabled efficient hydrolysis, resulting in 67% OTA degradation within 24 h directly in the extract, while preserving bioactive compounds and sustainably converting winery byproducts into potential cosmetic applications.