Application of Chitosan-Based Coatings Incorporating Sea Fennel Essential Oil and Rosemary Extract on the Chemical and Microbiological Characteristics of Sardine (Sardina pilchardus) and Gilthead Seabream (Sparus aurata)

Edible coatings have attracted increasing interest in the food industry owing to their biodegradability, non-toxicity, and potential to extend the shelf life of refrigerated fish by reducing lipid oxidation and microbial spoilage. This study evaluated the species-dependent effectiveness of bioactive edible coatings based on chitosan or chitosan–gelatin, enriched with sea fennel (Crithmum maritimum L.) essential oil and aqueous rosemary (Rosmarinus officinalis) extract. Two Adriatic fish species with contrasting biochemical characteristics, sardine (lipid-rich, pelagic) and gilthead seabream (lean, demersal), were coated and stored at 4 °C. Quality changes were monitored by sensory evaluation, thiobarbituric acid reactive substances (TBARS), proteolytic index, total volatile basic nitrogen (TVB-N), and microbiological analyses. Lipid oxidation, proteolysis, and TVB-N increased during storage, particularly in sardine. Chitosan-based coatings reduced proteolytic degradation more effectively than chitosan–gelatin coatings, although neither formulation significantly limited lipid oxidation in sardine. In contrast, the coatings were more effective in preserving the quality of gilthead seabream. These results demonstrate that the performance of edible coatings strongly depends on fish species, reflecting differences in biochemical composition and dominant spoilage pathways. The findings also highlight the importance of coating formulation, particularly the use of monopolymer versus blended systems, for developing effective preservation strategies for different fish products.