.3. Application of the antimicrobials to the turkey samples
The antimicrobials were added to the turkey fillets, either singly, or sequentially using the following procedure: a turkey meat filet (ca. 200 g ± 10 g) was transferred aseptically into an open sterile packaging pouch, containing 100 ml of chitosan solution (1.5% w/v). Each filet was individually dipped and remained in contact with the chitosan solution for 1.5 min. Immediately after dipping, the excess solution was drained off on a rack that was previously sterilized (absolute alcohol) and this procedure was done under aseptic conditions in a sterile cabinet. Each sample was then packaged into a clean sterile pouch. Rosemary oil (sterile, as previously determined, in our laboratory by measuring its total plate counts) was added onto the turkey samples (0.25 ml of oil onto 100 g of turkey meat) undiluted at a final concentration of 0.25% v/w using a Volar micropipette. Finally, for the combined antimicrobial treatment, chitosan solution was applied first to the samples, followed by rosemary oil, both added at concentrations previously applied. It must be noted that the selection of the final optimum concentration of each antimicrobial, applied to the turkey fillets, was established following preliminary microbiological analysis (determination of mesophilic TPC) and sensory evaluation of the turkey samples, treated with the aforementioned antimicrobials at selected concentrations in the range of 1–2% w/v (chitosan) and 0.1–1.0% v/w (rosemary oil) (results not shown). Additionally, to the treatments of the present study, preliminary experiments tested the effect of acetic acid on the quality of turkey fillets. Samples were analyzed sensorially (cooked) and microbiologically (TPC) (results not shown). It was concluded that addition of acetic acid to the turkey filet steaks (dipped in 1% w/v glacial acetic acid, similar to the treatment with chitosan solution in 1% w/v acetic acid) did not negatively affect the sensory parameters and did not have any effect on the mesophilic TPC of the product.