Effect of gelatin coating incorporated with thyme and laurel essential oils on the chemical, physical, microbiological and sensory quality of sea bream (Sparus aurata L., 1758) fillets

Thyme and laurel essential oil was used in gelatin coatings to maintain the quality of refrigerated seabream fillets over a period of 15 days. Fish fillets were coated with a solution of 15% fish gelatin incorporated with %1 thyme and %1 laurel essential oil and then stored in refrigerator (4 ± 1 _C). Coating?s preservative effect was assessed periodically (every 3 days) by microbial analyses (Total bacterial counts), chemical determinations (total volatile basic nitrogen, thiobarbituric acid, peroxide value, free fatty acid), physical (pH and hunter Lab color values) and sensory characteristics. Total bacterial counts reached higher populations in control and % 15 gelatin coating samples as compared to gelatin coating containing laurel and thyme oil samples (p<0.05) . Samples coated with gelatine enriched with laurel oil showed the lowest rate of total volatile basic nitrogen, peroxide and free fatty acid values (p<0.05) . The presence of thyme and laurel oil improved the color of seabream by increasing the L*-value and decreasing a*-value. As determined by sensory analysis (overall acceptability attribute) the observed shelf-life of seabream fillets was longest for gelatin coating containing thyme oil and laurel oil (15 days) followed by % 15 gelatin coating (9 days), and control (6 days) samples. The presence of thyme (1%) and laurel oil (1%) in seabream samples produced a distinct but sensorially acceptable pleasant odor, well received by the panellists.