Comparison of ferulic acid-crosslinked anthocyanins-fish gelatin-based intelligent hydrogels and films:...

Fish gelatin (FG) is a biopolymer with favorable biocompatibility, mechanical strength, and water retention, making it ideal for films, hydrogels, and bio-based applications. This study aimed to comparatively investigate the FG based intelligent films and hydrogels for monitoring shrimp freshness. Intelligent films and hydrogels were prepared using FG as a macromolecular matrix, incorporating ferulic acid (FA)-crosslinked anthocyanin (ACN) as an indicator, and enhanced with polysaccharides (κ-carrageenan (κC), xanthan glucomannan (XG), and konjac glucomannan (KGM)). UV-Vis spectroscopy and molecular docking analyses confirmed that FA-ACN copigmentation improved light stability and enhanced molecular interactions. Prepared intelligent films and hydrogels were characterized by evaluating mechanical strength, water retention, color stability, and sensitivity to freshness indicators. Results showed the addition of polysaccharides significantly enhanced mechanical strength and water retention of films, while the combination of FA and κC improved mechanical properties, water resistance, and color stability, and FA-FG-κC hydrogel had the strongest gel strength, reaching 1211.29 g. The intelligent hydrogels demonstrated superior sensitivity, with color changes closely correlated (R² > 0.9) to both TVB-N and TVC levels, thus accurately reflecting shrimp freshness during storage. Compared with films, hydrogels offered improved responsiveness and reliability. This work presents a sustainable, real-time monitoring strategy for aquatic products, contributing to food safety and environmental sustainability. These findings support the potential of FG-based intelligent hydrogels in quality monitoring of seafood during cold chain storage.