Smart funoran film incorporated with blueberry anthocyanins as a dual pH/NH3 sensor for real-time monitoring of shrimp freshness

The development of smart, biodegradable packaging materials endowed with spoilage detection functionalities is a promising approach to enhance food safety and quality assurance. In this study, a funoran-based pH/NH₃-sensitive smart film was developed by incorporating blueberry anthocyanins (BBA) as a natural pH indicator. The influence of BBA addition on the physicochemical characteristics of the film and its efficacy in monitoring the freshness of shrimp were evaluated. The rheological properties, Zeta-potential measurements, Fourier Transform Infrared Spectroscopy (FTIR), and X-ray diffraction (XRD) analysis indicated that BBA interacted with funoran by electrostatic interactions, which led to alterations in the intricate structural network and the crystalline structure of the involved materials. The smart film exhibited a homogeneous and compact structure, demonstrating significant thermal stability up to 100 °C. The incorporation of BBA reduced light transmittance (78.2 %–65 %), water vapor permeability (WVP) (8.93 × 10⁻⁸ to 2.68 g s⁻¹·m⁻²·Pa⁻¹), and oxygen permeability (OP) (190.98–132.13 cm³/(m²·day)). Conversely, the tensile strength (10.83–14.34 MPa), elongation at break (23.36–32.05 %), and antioxidant activity were significantly improved. The BBA solution exhibited sensitivity to variations in pH, and the funoran-based smart films (FBA) demonstrated notable colorimetric changes in various buffer solutions and ammonia. The smart film presented substantial colorimetric variations while evaluating the freshness of shrimp, particularly with the FBA 15 % formulation, showing superior sensitivity in freshness detection. These results suggest that the funoran film incorporating BBA can be effectively utilized as multifunctional smart packaging in the food industry.