Intelligent colorimetric indicator films were prepared to monitor freshness/spoilage of milk and fish by incorporating purple tomato anthocyanin (PTA) into chitosan (CS) matrix via solution casting method with PTA concentration… Click to show full abstract
Intelligent colorimetric indicator films were prepared to monitor freshness/spoilage of milk and fish by incorporating purple tomato anthocyanin (PTA) into chitosan (CS) matrix via solution casting method with PTA concentration (w/w, based on CS) of 10%, 30%, and 50%, respectively. The pH-response, UV absorption, Swelling Index, and the mechanical properties of CS/PTA films were determined. It was found that the color of the original CS/PTA films became darker with an improvement of PTA content and expressed well pH-sensitivity. With increasing of pH, the color of the CS/PTA films exposed to pH = 3-11 solutions became darker and the change in color of the CS/10% PTA film was the most discernable. The tensile strength and Young's modulus of the CS/PTA film was much lower than that of CS film, however, the elongation at breaking and Swelling Index were both improved by adding PTA. The intelligent films with 10% PTA changed their color during progressive spoilage of milk or fish, revealing their potential application for monitoring food freshness/spoilage.
               
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