Determination of quality changes of hot smoked rainbow trout (Oncorhynchus mykiss) fillets kept in the deep freeze for different storage time periods

In this study, rainbow trout (Oncorhynchus mykiss, Walbaum 1792), stored for 6 months (A) and 12 months (B) in deepfreeze (-18oC) and fresh (K: control) was subjected to hot smoking. Hot smoked rainbow trout was kept in refrigerator conditions (4±1°C) and the effect storage time in deep freezing on shelf life was evaluated by chemical (TVB-N, TBA, pH), microbiological (TMAB, TPAB, TYM, TCB) and sensory analyzes (color, smell, taste, general appreciation). TVB-N values which were determined as 15,41±0.25, 22,99±0,68 and 25,84±0,12 mg/100 g at the beginning of the experiment in K, A and B groups and determined as 36,56±0,35 (14th day), 36,80±0,33 (9th day) and 36,63±0,58 mg/100g (3th day) at the end of experiment, respectively. At the beginning of the trial, amounts of TBA, was determined as 0,62 ± 0,05, 0,71 ± 0,01 and 1,75 ± 0,02 malonaldehyde/kg in K, A and B groups and found as 8,55±0,01, 8,35±0,1 and 8,19±0,01 malonaldehyde/kg at the end of the trial respectively. The measured pH values of the K, A and B groups at the beginning of the experiment were 5,93 ± 0,04, 5,47±0,02 and 6,02 ± 0,01, respectively. These values were found as 6,11±0,01,6, 24±0.02 and 5.96±0.06, at the end of trial for K, A and B. The effect of freezing storage time on TVB-N, TBA and pH values was found significantly important (p<0.05). While the numbers of TMAB in groups K, A and B were 1,63±0,02, 2,29±0,03 and 2,3±0,02 logkob/g at the beginning of the experiment and these values were found as 6,33±0,08, 6,31±0,07 and 6,29±0,05 logkob/g at the end of experiment, respectively. When all the criteria (color, odour, flavour, texture and overall acceptance) of sensory freshness control methods were evaluated, shelf life was determined as 15 in group K, 12 in group A and 5 days in group B. According to these results, it is considered that the processing of trout stored for 6 months in deep freezing will be suitable for consumption and the processing of products stored for 12 months will not be suitable for shelf life.