Sustainable Extraction of Antioxidant Phytocompounds from Yellow Onion Wastes for Value-Added Product Development

Did you know that the humble onion skin you toss aside could be a goldmine of antioxidants? This study turns yellow onion waste into a treasure trove of health-boosting compounds.

Every year, mountains of yellow onion skins end up as waste. But scientists see potential, not trash. They've developed a green, ultrasound-assisted extraction method to pull out valuable phytochemicals like polyphenols and flavonoids. These compounds are prized for their health benefits, and the main star is quercetin, a powerful antioxidant. The team optimized the process using a Box–Behnken design, fine-tuning ultrasound amplitude, ethanol concentration, and time. The results were impressive: total polyphenol content reached up to 97.16 mg GAE/g DM, flavonoids up to 26.46 mg QE/g DM, and antioxidant activity (CUPRAC) up to 163.75 mg TE/g DM. The sweet spot was 30% amplitude, 53% ethanol, and 13 minutes—yielding near-maximal values. This means onion skins could become a cheap, sustainable source of antioxidants for food, cosmetics, or pharmaceuticals. So next time you peel an onion, remember: you're holding potential, not waste.

Key Points

• Ultrasound-assisted extraction yields quercetin-rich onion skin extracts.
• Optimized conditions: 30% amplitude, 53% ethanol, 13 minutes.
• High antioxidant activity up to 163.75 mg TE/g DM.