Biodegradable pectin films incorporating purple sweet potato anthocyanins for real-time shrimp freshness monitoring

This study aimed to develop biodegradable films using pectin extracted from orange peel residues, purple sweet potato extract, and glycerol, with potential application for monitoring shrimp freshness. The physical, barrier, mechanical, bioactive, antioxidant, morphological, structural, and thermal properties of the developed material were evaluated, as well as its viability as a freshness indicator for shrimp. The extracted pectin showed a high yield (45.44%), equivalent weight (1807.76 g), and methoxyl content (79.26%), indicating the quality of the obtained biopolymer. Films containing anthocyanin extract from purple sweet potato (FE) exhibited a predictable and sensitive color response to pH variations, confirming their applicability as visual indicators for food freshness and quality monitoring. The incorporation of anthocyanin extract significantly influenced the films’ physical, barrier, and mechanical properties, improving their strength and flexibility (p < 0.05). The FE showed a higher total phenolic content (1400.65 mg GAE/100 g), anthocyanin content (375.28 mg/100 g), and significantly greater antioxidant capacity compared to the control film (FC). The overall migration of film constituents was considerably higher in water than in acetic acid and ethanol. Morphological and structural analyses revealed that anthocyanin extract did not substantially alter the film’s surface or cause significant structural changes in the pectin matrix. Still, it exhibited the highest melting temperature (253.64 °C). Changes in total volatile basic nitrogen (TVB-N) content and pH fluctuations affected the film’s color response. Finally, the findings of this study demonstrated that the fabricated pH indicator film is pH-sensitive and can be used to monitor shrimp freshness.