The effect of liquid smoking of fillets of trout (Salmo gairdnerii) on sensory, microbiological and chemical changes during chilled storage

The storage time at 4 ± 1 °C of liquid smoked fillets of trout (Salmo gairdnerii) produced with a new smoking technique, using a combination of liquid smoke and steaming at 2 bar pressure for 30, 45 and 60 min, was studied. Maximum total viable counts (TVC) were reached after 25 days in the samples processed for 30 min and after 48 days in those processed for 45 and 60 min. However, panellists rejected the samples long after maximum TVC was observed. The increase of TVC was also confirmed using a particle size analyser, indicating a possible direct detection of microbial growth. A reduction of about 50% in the C22:6n − 3/C16:0 ratio was found across the whole period of storage, indicating lipid oxidation. The hypoxanthine/inosine (Hx/Ino) ratio showed a good relationship with both TVC and sensory results. Thus, when the Hx/Ino ratio was higher than 1.3, the products had reached their maximum acceptable TVC and were approaching their rejection time by the panellists, indicating that the Hx/Ino ratio is a good indicator of the shelf-life of smoked products of trout (S. gairdnerii).