Quality improvement of refrigerated sardine fillets using shrimp waste-based edible coatings

The development of sustainable packaging solutions is becoming increasingly important for preserving food quality, minimizing waste and promoting the valorisation of food industry waste/by-products. The aim of this study was to develop an astaxanthin-rich extract from red shrimp (Aristaeomorpha foliacea) waste for incorporation into edible chitosan-based coatings. The effectiveness of coatings with and without astaxanthin in maintaining the quality and stability of fresh sardine fillets (Sardinapilchardus) during cold storage was evaluated to support circular economy strategies in the seafood sector. The fillets were coated with two formulations: chitosan alone (Ch) and chitosan with 2.5 % (v/v) astaxanthin extract (Ch+Asx). A control sample without coating was also included. All samples were packed in air in polypropylene trays and stored at 4 degrees C for 13 days and periodically analysed for headspace-gas composition, pH, water activity, colour, texture, lipid oxidation and microbial growth. The shrimp shell extract had a carotenoid content of 443.5 mu g astaxanthin/g and showed strong antioxidant capacity (DPPH=77.8 %; TEAC=576.3 mu mol TE/mL). Both edible coatings were able to slow down sardine deterioration compared to the control, with the Ch+Asx one showing the greatest effect in reducing microbial load (Enterobacteriaceae: 2.9 vs 6.3 log CFU/g; coliforms: 1.5 vs 5.9 log CFU/g after 13-days) and maintaining colour and texture. Lipid oxidation was significantly lower in both coated samples. These findings highlight the potential of using chitosan-based coatings enriched with natural antioxidants from shrimp waste as a promising solution for extending the shelf life of fresh seafood products while supporting waste valorisation and sustainable processing.