Enhancing Trout Fillet Preservation Using Chitosan Coatings Enriched with <i>Scrophularia Striata</i> Extract: Comprehensive Evaluation of Organoleptic, Microbial, and Chemical Properties

Background: The highly perishable nature of trout fillets necessitates the development of effective preservation strategies to extend shelf life and maintain quality. Objectives: This study aimed to develop a novel bioactive coating based on chitosan (CH) enriched with Scrophularia striata extract. Methods: Trout fillets were divided into four treatment groups: Control (untreated), CH film, S. striata extract dip, and CH film incorporating with S. striata extract (CH+SS). The fillets were stored at 4°C for 12 days, during which they were periodically evaluated for microbial growth, chemical indices of spoilage (TVB-N, pH, PV, TBARS), and sensory attributes (color, odor, texture). Results: The CH+SS treatment demonstrated the most significant preservative effect. On day 12, the Pseudomonas count in the CH+SS group was undetectable, which was substantially lower than in the control (7.19 ± 0.03 log CFU/g), S. striata extract (7.01 ± 0.03 log CFU/g), and CH (4.81 ± 0.16 log CFU/g) groups (P < 0.05). Similarly, the TVB-N value for the CH+SS group (20.75 ± 0.02 mg/100 g) remained within the acceptable limit, while the control and S. striata extract groups exceeded the rejection threshold (> 30 mg/100 g). Sensory scores for color, odor, and texture were consistently and significantly superior in the CH and CH+SS groups throughout the storage period. Conclusions: The CH+SS creates a synergistic effect that effectively inhibits microbial growth and mitigates chemical spoilage in trout fillets. The CH+SS coating is a promising natural solution for significantly extending the shelf life of refrigerated trout fillets beyond 12 days, especially antibacterial, while preserving their sensory quality.