Purple carrot anthocyanin-enhanced gelatin-chitin films for colorimetric detection of fish adulteration by formalin and ammonia

This research focused on fabricating a smart film using gelatin (G) and chitin nanofiber (CNF) nanocomposites, which were enhanced with varying levels of anthocyanin derived from purple carrots (PCA) and used to detect ammonia and formalin in fish. The addition of 10 wt% CNF results in the enhancement of the mechanical properties of pH indicator films. The study examined the PCA solution's spectral properties, the films' cross-sectional structure, and their responses to FT-IR spectroscopy and SEM images. Additionally, the research analyzed the mechanical attributes and the films' color response to various pH levels. Films with the greatest concentration of PCA were found to have the most uneven surface and the greatest dimensions, with a thickness of 0.233 mm. They also had the highest moisture level at 18.12%, the most significant elongation at break at 9.63%, and the strongest tensile strength at 11.46 MPa when compared to their counterparts. The gelatin-derived smart films exhibited significant color shifts from a vivid red to green across the pH spectrum of 2 to 12, with those containing 6% PCA displaying notable color transitions. All statistical tests were performed at a statistical significance level of at least 0.05 ( p value < 0.05). As a result, the gelatin-chitin nanocomposite films that include PCA are highly promising for identifying fish contamination.