Determination of shelf life of Salmo trutta macrostigma (Dumeril, 1858) packed at different ways at 4±1°c

In this study, effects of different packaging techniques and storage temperatures on quality characteristics of Salmo trutta macrostigma were investigated. Internal organs removed and cleaned Salmo trutta macrostigma was packed by ordinary, vacuumed and modified atmosphere (40% CO2 + 60% N2) techniques. Packed groups were storaged at 4±1°C and certain days of storage (0, 2, 4, 6, 8, 10, 12, and 14.) chemical (pH), total volatile base nitrogen (TVB-N), thiobarbituric acid (TBA), microbiological (total aerobic mesophilic bacteria number, total aerobic psycrophilic bacteria number and yeast-mold number) and sensory quality analysis were performed.According to the chemical analysis, TVB-N and TBA values increased significantly in all groups during storage period (p<0.05). According to the TVB-N values; ordinary group, vacuumed group and modified atmosphere group lost the consumption feature on 8th (35,13 mg/100g), 12th (37,70 mg/100g) and 14th (42,00 mg/100g) days respectively. TBA did not reached limit values during the study.Considering the microbiological criteria, the number of mesophilic and psycrophilic aerobic bacteria exceeded the limit values on 8th day of storage. Again, in terms of microbiological quality it was determined that the best group was modified atmosphere packed group during 12 days of storage period.According to the sensory analysis, ordinary group samples spoiled on 8th day, on this day bacterial load of samples for mesophilic and psycrophilic aerobic bacteria was found significantly high compared with vacuumed and modified atmosphere groups. In terms of sensory analysis results, shelf life of Salmo trutta macrostigma storaged at 4±1°C was determined as 6 days for ordinary group, 10 days for vacuumed and 12 days for modified atmosphere group.Consequently, it was concluded that modified atmosphere packaging and cold storage contribute longer protection of chemical, microbiological and sensory quality of fish.