Natural pH-Sensitive Intelligent Edible Gel-Based Packaging: From Structural Design to Fruit Freshness Monitoring

The escalating demand for global fruit logistics underscores the urgency of packaging innovations to reconcile preservation efficiency with environmental sustainability, particularly addressing microplastic pollution from conventional plastics and safety hazards posed by synthetic pH-sensitive pigments. Natural pH-sensitive intelligent edible gel-based packaging, which integrates non-toxic indicators into biopolymer gel matrices, offers a viable solution by visually tracking freshness through colorimetric responses to pH fluctuations during storage and transportation. This review systematically synthesizes recent progress in material design, including the development of edible films and coatings, and evaluates the functional mechanisms of natural pH indicators within these systems. Applications across diverse fruit categories demonstrate their efficacy in delaying ripening, inhibiting microbial growth, and signaling quality degradation via dynamic color shifts. Despite enabling real-time, visual freshness monitoring, challenges in mechanical robustness, water resistance, and scalable manufacturing remain. Future advancements should prioritize the integration of multifunctional systems, such as gas conditioning technologies and bioactive components, to enhance practical performance and align with sustainable food preservation objectives, ultimately reducing food waste and elevating consumer safety standards.