Strategies to enhance pH-responsivity of betalain-based biopolymer films

Betalain, a nitrogen-containing pigment traditionally employed as a food colorant, is harnessing interest for smart food packaging applications due to its exceptional antioxidant capacity and distinct halochromic behavior. However, there are key limitations associated with the inefficient extraction processes requiring substantial solvent use or long processing durations, and rapid degradation that compromises functional (e.g., antibacterial and antioxidant) and pH-responsive properties, curtailing the successful industrial translation of betalain in freshness monitoring of protein-rich foods. Accordingly, this review evaluates advanced strategies to enhance betalain yield from plant waste using novel extraction technologies, such as microwave-, ultrasound-, and enzyme-assisted methods, and identifies emerging encapsulation approaches, including inclusion complexes, nanoliposomes and metal organic frameworks to improve the pH-responsive performance and regulate pigment release of betalain-based packaging materials. Further sections examine the immobilization of betalains within diverse polymer matrices and the resulting effects on film morphology, mechanical behavior, barrier performance, and colourimetric responsiveness. All in all, this review demonstrates that integrating advanced extraction and encapsulation strategies can substantially reduce production bottlenecks and enhance the functional performance of betalain-incorporated films, thereby strengthening the prospects of betalain-based smart packaging as a robust, eco-friendly alternative for real-time food quality monitoring.