Plasma-Assisted Extraction of Bioactive Compounds from Tomato Peels and Sugar Beet Leaves Monitored by Electron Paramagnetic Resonance Spectroscopy

What if your tomato peels and beet leaves could become a treasure chest of antioxidants? A new study uses plasma-like electric sparks to unlock their hidden value.

Every year, tons of tomato peels and sugar beet leaves end up as waste. But these humble by-products are packed with bioactive compounds—lycopene, beta-carotene, chlorophyll, and phenolics—that could be turned into valuable ingredients for food, cosmetics, or medicine. The challenge? Extracting them efficiently without harming the environment.

Scientists turned to high-voltage electrical discharge (HVED), a technique that sends powerful sparks through a liquid, creating plasma and shockwaves that break plant cells open. They tested treatments lasting 1, 3, and 5 minutes, using two solvent strengths: 30% and 50% methanol. The results were striking: a 5-minute HVED in 50% methanol boosted lycopene extraction to 2.04 mg/100 mL and beta-carotene to 1.14 mg/100 mL. Meanwhile, shorter 3-minute runs maximized total phenolic content (0.117 mg GAE/mL in tomato peels, 0.280 mg GAE/mL in beet leaves) and chlorophyll (25.47 mg/100 mL).

To verify the antioxidant power, the team used electron paramagnetic resonance (EPR) spectroscopy, a direct and sensitive method that detects free-radical scavenging. All treated samples showed increased antioxidant activity, with the highest values at 45.27% for tomato peels and 53.16% for beet leaves. The 50% methanol consistently outperformed the 30% solution, proving that solvent strength matters.

HVED emerges as a green, effective tool for recovering bioactives from agricultural waste. It's a win-win: less waste, more value, and a cleaner planet.

Key Points

• HVED boosts extraction of lycopene, beta-carotene, chlorophyll, and phenolics.
• 5-min HVED in 50% methanol maximizes lycopene (2.04 mg/100 mL).
• EPR confirms antioxidant activity up to 53.16% in treated samples.