Preparation and Evaluation of Biodegradable Film From Zinc Oxide Nanoparticles‐Carboxymethyl Cellulose‐Gelatin Containing <i>Salvia viridis</i> Anthocyanin

ABSTRACT In recent years, growing environmental concerns have promoted the use of natural and biodegradable polymers in food packaging applications. The production of smart packaging using natural pigments and biodegradable polymers is essential for improving the quality and freshness of food. This study aimed to develop an edible, pH‐sensitive smart film based on gelatin, carboxymethyl cellulose and zinc oxide nanoparticles, incorporating Salvia viridis anthocyanins as a natural colorimetric indicator. The innovation of this work lies in the use of Salvia viridis anthocyanins for smart packaging, which has not been previously explored. Edible films containing Salvia viridis anthocyanins at levels of 20, 40, and 80 mg/100 mL in the film solution were prepared and evaluated for their mechanical, structural, and color properties. In addition, this film was conducted to indicate fish freshness. The incorporation of anthocyanins significantly affected the film's mechanical and physical characteristics. Films without anthocyanins exhibited the lowest elongation, whereas those containing 80 mg anthocyanins demonstrated the highest elongation. The control film (without anthocyanins) showed the highest tensile strength (33.73 MPa) and the lowest turbidity (0.75), with turbidity increasing proportionally to anthocyanin content. The films'color mactched those of the anthocyanin extract solutions, confirming the pH sensitivity of the developed films. The film displayed visual color changes during the fish storage period. The findings indicate that Salvia viridis anthocyanins film is a useful tool for monitoring the freshness of food products.