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 ( Sardina pilchardus ) 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°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 µg astaxanthin/g and showed strong antioxidant capacity (DPPH=77.8 %; TEAC=576.3 µmol 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. • Chitosan-based coatings applied to fresh sardine fillets to extend shelf life • Astaxanthin obtained from red shrimp waste for edible coating activation • Lipid oxidation and microbial growth reduced in coated sardine fillets • Preservation technologies for seafood sector using waste support circular economy