Developing high-performance shrimp smart packaging: Chitosan/Whey protein isolate/betacyanins films enriched with natural carbon dots

• Synthesized Ch/WPI/MBs/CM-CDs film via casting method for enhanced properties. • MBs and CM-CDs improved the physicochemical features of the composite film. • Antibacterial/antioxidant activities were boosted by MBs@CM-CDs addition. • pH shifts from 2 to 13 caused a color change from pink to yellow, showing pH sensitivity. • The film detected shrimp freshness within 48 hours at room temperature. Conventional packaging systems often rely on passive preservation and lack real-time quality monitoring. This study introduces a high-performance chitosan/Whey protein isolate (Ch/WPI)-based colorimetric indicator composite film embedded with Mirabilis jalapa betacyanins (MBs) and chamomile waste carbon dots (CM-CDs), which provides improved pH responsiveness along with notable antimicrobial/antioxidant potential and UV-blocking properties. Results showed good compatibility, leading to uniform films with improved physicomechanical properties. CM-CDs is uniformly distributed within the Ch/WPI matrix, forming hydrogen bonds between its moieties. The proposed films indicated several advantageous properties, including good antibacterial activity against S. aureus (20±1.2 mm) and E. coli (15±0.36 mm) strains and potent antioxidant properties (83±1.7%). The thickness, tensile strength, elongation at break, water solubility, moisture content, water contact angle, and water vapor permeability of the suggested Ch/WPI films were 50-60 μm, 79.42-91.74 MPa, 4.36-8.8 %, 68.5-47.6 %, 29.0-4.99%, 81.5-85.1°, and 6.90-2.54 × 10 −11 g m −1 s −1 Pa −1 , respectively. The Ch/WPI/MBs/CM-CDs film was pinkish-red, pink, yellowish-brown, and yellow at pH values 2, 4, 6, 7, 8, 10, and 12, respectively, indicating its potential as a suitable pH-responsive films/labels. To assess the potential of fabricated films for tracking shrimp freshness, samples became inedible after 48 h at room temperature, with pH values of 7.43. Meanwhile, the films' color shifted visibly from purplish red to brownish-yellow, indicating their suitability for real-time, visual detection of spoilage in shrimp.