Fabrication of intelligent pH-sensing films with antioxidant potential for monitoring shrimp freshness via the fortification of chitosan matrix with broken Riceberry phenolic extract

• A wide pH-sensing colorimetric film based on chitosan and broken Riceberry phenolic extract was developed. • Addition of 1 wt% Riceberry phenolics substantially improved the mechanical properties of the indicator film. • The intelligent film displayed excellent antioxidant and improved light barrier properties. • The intelligent film was sensitive to changes in pH (2–12) and volatile ammonia. • The intelligent film can be effectively applied for visual monitoring of shrimp spoilage. There is growing interest in chitosan-based intelligent packaging films for monitoring food quality. However, practical application of these biopolymeric films has been limited by their poor physical and mechanical attributes. Herein, a versatile colorimetric indicator film was developed based on chitosan (CHI) and broken Riceberry phenolic extract (RPE). The effects of RPE fortification on the microstructure, physical, and functional attributes of the CHI films were comprehensively evaluated. The results revealed that CHI-RPE films exhibited increased hydrophobicity, mechanical resistance, thermal stability, barrier properties, and antioxidant activity compared to plain CHI film. The CHI-RPE films were cytocompatible. Notably, CHI-RPE film also produced intense naked-eye detectable colorimetric response to pH (2–12) variation and volatile ammonia. When enclosed with fresh shrimp, CHI-RPE film changed from orange-red to yellow in response to shrimp spoilage. Thus, CHI-RPE film has high potential for fabricating pragmatic, smart packaging labels for on-site visual detection of freshness in seafood products.