چكيده به لاتين
Smart packaging with the ability to monitor product quality in terms of freshness and active packaging that extends shelf life can help preserve product quality over time. Integrating these two technologies into a system based on eco-friendly, industrially feasible, and cost-effective materials not only reduces waste and protects the environment but also enhances consumer experience by providing fresher and safer products. In this study, an innovative, eco-friendly, smart, and active system was developed by creating color-indicator films sensitive to ammonia and possessing antibacterial properties based on polylactic acid (PLA) combined with thermoplastic starch, cochineal dye, and clove essential oil. The effects of adding thermoplastic starch and thermoplastic starch modified with citric acid on the physical and chemical properties of the films, including ammonia sensitivity, color stability, tensile properties, water vapor permeability, antibacterial properties, as well as their performance in monitoring freshness and extending the shelf life of shrimp, were evaluated. Additionally, the performance of films containing anthocyanin extracted from grape skin in monitoring the freshness of packaged shrimp was investigated. The results showed that the addition of modified thermoplastic starch to PLA improved phase adhesion, better dispersion, and reduced starch particle size in the PLA matrix compared to the base blend, leading to enhanced tensile, barrier, and color stability properties of these films. Increasing the percentage of thermoplastic starch in the films resulted in heightened sensitivity to ammonia. A 20% addition of thermoplastic starch led to a 141% improvement in the rate of color change in response to ammonia compared to PLA films without thermoplastic starch, with a further 25% improvement achieved by modifying the starch, resulting in a more uniform color change. The performance of PLA films containing modified thermoplastic starch in monitoring shrimp freshness showed good correlation between color change and the shrimp spoilage index (TVB-N), with a visual color shift from orange to purple as shrimp spoiled over 24 hours at 28°C. Additionally, these films extended the shelf life of shrimp stored at 4°C from 5 days to 15 days, with a visible color change on day 15, coinciding with shrimp spoilage, demonstrating the film's dual function in extending shelf life and visually indicating spoilage. Films containing anthocyanin also exhibited successful color changes from red to green upon shrimp spoilage, with desirable sensitivity to ammonia.
