Research progress on plant polysaccharide-based intelligent-responsive films: Substrates, forming mechanisms, preparation methods, response types, and applications in food preservation

To address the ecological challenges, including climate change, environmental pollution, and microplastic pollution caused by traditional petroleum-based films, plant polysaccharide-based films have become a sustainable alternative in the field of food preservation. Unfortunately, conventional plant polysaccharide-based films still have limitations, including low mechanical strength, poor water vapor barrier properties, and lack of active response capabilities. In recent years, plant polysaccharide-based intelligent-responsive films (PPIFs), as the new type of functional materials, can sensitively perceive external environmental stimuli (pH, temperature, humidity, etc.) and respond accordingly, thereby enhancing the preservation effect of food. For instance, the pH-responsive films based on anthocyanins exhibited a significant color change (ΔE > 5) within the pH range of 3 to 10, which could be utilized for the visual monitoring of volatile amines during food spoilage. This paper systematically reviews the substrate classification, structural properties, and film formation mechanisms of PPIFs, also focuses on summarizing their preparation techniques and response types, and outlines their application progress in different food systems (fruits, meats, and seafood). However, PPIFs still encounter key problems, such as insufficient stability of the active components, limited response sensitivity, and high costs for large-scale production. Future research can enhance the stability and functional responsiveness of materials through multi-component collaborative design, nanotechnology enhancement, and green processing techniques. The findings can provide theoretical references for the development of more efficient and environmentally friendly intelligent food packaging materials.