Enhanced shelf life of trout fillets using an edible coating containing the polysaccharide extracted from Loquat (Eriobotrya japonica) seed

This study aimed to evaluate the effect of an edible coating enriched with polysaccharides extracted from loquat (Eriobotrya japonica) seeds on the microbial, chemical, and sensory quality of trout fillets during 12 days of cold storage. The highest polysaccharide yield (48.2 %) was achieved by applying microwave treatment at 540 W for 15 min. The extract exhibited remarkable antioxidant properties, including 57 % 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 64 % hydroxyl radical (HO) scavenging activity, as well as strong ferric reducing antioxidant power (0.7 absorbance at 700 nm), suggesting its excellent potential to delay oxidative spoilage. To formulate the coating, different ratios of gelatin and loquat seed polysaccharide were tested (G1-P0, G1-P0.5, and G1-P1). Increasing the polysaccharide content resulted in a significant reduction in the growth rate of total and psychrophilic bacteria during storage. Moreover, lower pH values were observed in treatments with higher polysaccharide concentrations. Samples with more polysaccharide also showed reduced levels of chemical spoilage indicators, including peroxide value (PV), thiobarbituric acid reactive substances (TBA), free fatty acids (FFA), total volatile basic nitrogen (TVB-N), and trimethylamine (TMA), all of which are known markers of lipid oxidation and protein degradation in trout fillets. Sensory evaluations confirmed that fillets coated with polysaccharide-rich formulations had significantly better scores in odor, color, and overall acceptability compared to uncoated samples. This study introduces a novel application of loquat seed polysaccharides in edible coatings, offering enhanced preservative effects compared to traditional gelatin-based coatings for trout fillets.