The effects of Lactococcus lactis on organoleptic and some bacteriological factors in rainbow trout vacuumed fillets

This study was carried out to determine the effects of supernatant of Lactococcus lactis to increase the shelf life of rainbow trout fillets (Oncorhynchus mykiss). After preparation of the bacterium from the Iranian Scientific and Industrial Research Organization, they were cultured in MRS medium. Bacteria with dilution of ۱۰۶ CFU/ml and ۳۰% and ۶۰% of supernatant were prepared. There effects on ۹۶ samples of ۱۰۰ grams’ fish fillets using of immersion method at ۴°C was investigated. The results showed that the average logarithm of psychrophilic, psychrotrophic, mesophilic bacteria, mold and yeast in grams of fillet was significantly lower than that of control (which exceeded the log limit of human=۷ CFU / g) (p<۰.۰۵). Sensory tests (odor, taste, texture and color) were tested and showed no significant difference (p>۰.۰۵) except for pure bacteria. In terms of taste, the supernatant and pure bacteria were at a good level at the end of day ۱۵ but other treatments were in non-consumable condition. But there was a significant difference among treatments (p˂۰.۰۵). In fact, we noted that the more supernatant has more effects on enhancement of fillets shelf life.

Keywords:

supernatant , Lactococcus lactis , Bacteria , Rainbow trout , Fillets