Comparative Evaluation of Ultrasonic, High Pressure, and Pulsed Electric Field Processing on the Extraction and Storage Stability of Betalains From Red Beet By-Products

Red beet peels and stalks are usually thrown away — but they may hide a treasure trove of natural pigments. A new study shows that a simple 10-minute ultrasound bath could unlock their full potential.

Food waste often hides surprising value. This study focused on red beet peel and stalk, two underutilized by-products, as rich sources of betalains, phenolics, flavonoids, and antioxidants. Three green, non-thermal technologies — high pressure, ultrasound, and pulsed electric fields — were put to the test for extraction efficiency.

Ultrasound won clearly. Sonication at 300 W for just 10 minutes produced the highest concentrations of bioactive compounds from both peel and stalk. But extraction is only half the story. The researchers also tracked how these compounds behaved over 120 days in cold storage, using kinetic modeling to understand degradation patterns.

Betalains and phenolics degraded following first-order kinetics, while antioxidant activity actually increased over time, fitting a zero-order model. Among sonicated samples, betaxanthins proved more stable than betacyanins, showing superior pigment persistence.

This work goes beyond simple yield measurements. By integrating degradation kinetics with extraction optimization, it offers a practical roadmap for turning red beet by-products into shelf-stable, functional ingredients — a timely insight for the food and nutraceutical industries.

Key Points

• Ultrasound (300 W, 10 min) best extracts bioactives from beet peel and stalk.
• Betalains and phenolics degrade by first-order kinetics; AOX increases over 120 days.
• Sonicated betaxanthins more stable than betacyanins in cold storage.