Valorization of red beet peel through green extraction and carrier-driven microencapsulation for improved betalain stability

The utilization of agri-food by-products and waste is increasingly essential due to sustainability trends and global regulations. Incorporating these nutrient-rich yet underutilized materials into food production enhances both sustainability and economic efficiency. This study evaluated and compared the extraction of betalains from red beet peel (RBP) using ultrasound-, high pressure-, and pulsed electric field-assisted techniques. Sonication yielded the highest levels of total betalains (16.92 ± 0.19 mg/g DM), phenolics (60.36 ± 0.32 mg GAE/g DM), flavonoids (18.49 ± 0.19 mg CTE/g DM), and antioxidant activity (112.10 ± 0.36 μM TE/g DM). Additionally, the stability of sonicated RBP betalains was analyzed using soy protein isolate (SPI) and maltodextrin (MD) as encapsulating agents. Both effectively reduced degradation, with betalain changes fitting zero-order kinetics over 120 days. The predicted shelf-life of encapsulated extracts was 7-12 months, significantly longer than non-encapsulated extracts (5 months). These findings highlight red beet peel as a sustainable source of natural pigments, demonstrating that eco-friendly extraction combined with encapsulation can effectively enhance both the stability and shelf-life of betalains, offering promising applications in functional foods and natural colorant development.