Development of quality index method (QIM) scheme for farmed tilapia fillets and its application in shelf life study

The aim was to develop a Quality Index Method (QIM) scheme for fresh tilapia fillets and evaluate the scheme in a shelf life study. Farmed tilapia fillets were stored at 1 and -1°C for up to 20 days, and changes during storage were observed with sensory evaluation using the QIM scheme and General Descriptive Analysis (GDA), total viable counts (TVC), and hydrogen sulphide (H₂S) producing bacteria. The maximum shelf life of fillets stored at1 and -1°C was determined with GDA and microbial counts as 16 and 19 days, respectively. A high correlation of R² = 0.943 between Quality Index (QI) and storage time at 1C° was found to be 0.843 at -1°C. At the end of shelf life, the QI was 5.3 and 6.5 out of a maximum score of 15 for fillets stored at 1 and -1°C, respectively. Total viable counts and H ₂S-producing bacteria showed an increasing trend during storage time for both groups. At the end of shelf life, TVC was log 7 cfu/g in the flesh of both groups, with H₂S producing bacteria constituting a higher proportion (log 6 cfu/g) of the total. The scheme was modified at the end of the study to better characterize deskinned farmed tilapia fillets.