Recovery of Natural Antioxidants from Onion Solid Waste via Pressurized Liquid Extraction: Encapsulation and Application into a Food System

Onion solid wastes (OSW) are a promising source of natural antioxidants with potential applications in food preservation. This study optimized pressurized liquid extraction parameters—ethanol concentration, liquid-to-solid ratio, temperature, and time—using response surface methodology to maximize the recovery of total polyphenols, total antho- cyanins, and antioxidant activity. The optimal extracts yielded 37.02 mg GAE/g dw for total polyphenols and 592.73 μg CyE/g dw for total anthocyanins....