Sea Fennel (Crithmum maritimum) as a Clean-Label Ingredient to Improve Oxidative and Microbial Stability of Refrigerated Horse Mackerel Meatballs

Horse mackerel is nutritionally valuable but highly prone to quality loss during chilled storage because its PUFA-rich lipids readily oxidize in comminuted products. Therefore, clean-label strategies are required to delay oxidation and spoilage. This study evaluated the effect of adding sea fennel (Crithmum maritimum), either as a plant homogenate incorporated at 5% (P-5%), 10% (P-10%) and 20% (P-20%) or as a dried polyphenolic extract at 0.25% (E-0.25%), 0.5% (E-0.5%), and 1% (E-1%), on the shelf-life of horse mackerel meatballs stored at 4 °C. Lipid oxidation, including free fatty acids (FFA), peroxide value, conjugated dienes, and thiobarbituric acid reactive substances (TBARS), antioxidant activity (ABTS and FRAP analyses), color (CIELAB color space), pH, total volatile basic nitrogen (TVB-N), spoilage-associated microbial groups, and volatile profiles were monitored during storage. Sea fennel reduced secondary oxidation compared to the control, with P-20% showing the lowest TBARS, corresponding to an approximately five-fold decrease compared with the control, and E-1% showing the clearest suppression of oxidation-derived aldehydes in the volatile fraction. The incorporation of either the plant homogenate or the extract reduced microbial growth, particularly that of Pseudomonas spp., while lactic acid bacteria counts increased during storage. This contributed to extend the microbiological shelf life of P-20% and E-1% by approximately 3 days. P-20% and E-1% also showed lower pH and TVB-N values over time. Overall, sea fennel improved the oxidative stability and early microbial control of refrigerated horse mackerel meatballs. However, whole-plant incorporation requires further optimization to balance matrix effects, quality evolution, and potential sensory changes.