The effect of different oregano (Origanum onites L.) extracts on quality of vacuum packaged rainbow trout (Oncorhynchus mykiss Walbaum, 1792) fillets in refrigerator (+2±1 °c)

In this study, changes of biochemical, physicochemical, microbiological, textural and sensorial in vacuum packaged rainbow trout (Oncorhynchus mykiss Walbaum, 1792) fillets applied different oregano (Origanum onites L.) extracts during the 21-day storage were investigated. Samples divided into five different groups as control group (KO), hot infusion of 3% (SID), cold infusion of 3% (SOD), distillation of 3% (DES) and boiling of 3% (KAY) and, vacuum packaged, then stored in refrigerator (+2±1 °C). Significant changes were not determined in the biochemical content of rainbow trout fillets applied different oregano extracts (p>0.05). At the end of storage, values of L and a+ of all groups were found lower than values of raw material, whereas values of b+ were found higher. Texture values of all groups at the end of the storage were found higher than beginning value. At the end of the study, thiobarbituric acid (TBA) values of KO, SID, SOD, DES and KAY groups was found as 4,06, 3,18, 3,38, 3,37 and 4,32 mg malonaldehit/kg, respectively. Total volatile basic nitrogen (TVB-N, mg/100g) values of all groups except for distillation group exceed limit values on day 17. Total aerobic mesophilic bacteria (TAMB) count in all groups while staying within limit values on day 13, total aerobic psychrophilic bacteria (TAPB) count is determined to not exceed the limit values of quality during the 21-day storage period. Total coliform values of KO, SID, SOD, DES and KAY groups were exceed the limit values on day 13, day 17, day 17, day 21 and day 17, respectively. According to the sensory evaluation, SOD and DES groups were found within consumable limits 17 days, whereas other groups were 13 days. According to results of this study, rainbow trout fillets can be safely consumed in 9 days for KO and SID groups, 13 days for SOD and KAY groups, 17 days for DES group.