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

This study explores the potential of red beet peel (RBP) and red beet stalk (RBS), often underutilized by-products, as rich sources of natural pigments and bioactive compounds. Three non-thermal green extraction methods, namely, high-pressure processing, ultrasound, and pulsed electric field treatment, were evaluated for their efficiency in extracting betalains, total phenolics, flavonoids, and antioxidant activity (AOX). Among these, sonication at 300 W for 10 min proved most effective for both RBP and RBS, yielding the highest concentrations of bioactives. Crucially, this work goes beyond conventional yield assessments by addressing the post-extraction storage stability of these compounds over 120 days under refrigeration. Kinetic modeling revealed that betalains and phenolics degraded following first-order kinetics, whereas AOX increased over time and followed a zero-order model. Sonicated samples demonstrated superior pigment stability, with betaxanthins more stable than betacyanins. This study highlights the importance of integrating degradation kinetics with extraction optimization and offers a novel perspective on the valorization of red beet by-products. The findings are particularly relevant for food and nutraceutical industries seeking to develop shelf-stable, functional plant-based ingredients.