2.4. Microbiological analysis
The standard plate count method was used to determine the initial microbial load and the effectiveness of the treatment in reducing the number of mesophilic microorganisms naturally present on the surface of the meat. The samples were treated, mixed in a sterile vial with 4 ml of Phosphate Buffer Solution (PBS, pH 7.4) and subsequently stomached at 230 rpm for 2 min (Stomacher 400; International P.B.I., Milan, Italy). The homogenate was serially diluted in PBS and plated onto Plate Count Agar medium (Liofilchem, Italy). At the end of the incubation period (48 h, 30 ± 2 C), the number of colonies was counted and the degree of inactivation was determined by evaluating the Log (N/N0) versus time, where N0 (CFU/cm2 ) was the number of microorganisms initially present on the untreated sample and N (CFU/cm2 ) was the number of survivors after the treatment. Two independent experiments were carried out for each experimental condition and the results were reported as mean values and standard deviations. The initial microbial load of the samples was 5.18 ± 0.83 Log (CFU/cm2 ).