The presence of Staphylococcus aureus in six dry-cured meat-processing facilities was investigated. S. aureus was detected in 3.8% of surfaces from five facilities. The occurrence was clearly higher during processing (4.8%) than after cleaning and disinfection (1.4%). Thirty-eight isolates were typified by PFGE and MLST. Eleven sequence types (STs) were defined by MLST. ST30 (32%) and ST12 (24%) were the most abundant. Enterotoxin genes were detected in 53% of isolates. The enterotoxin A gene (sea) was present in all ST30 isolates, seb in one ST1 isolate, and sec in two ST45 isolates. Sixteen isolates harbored the enterotoxin gene cluster (egc) with four variations in the sequence. The toxic shock syndrome toxin gene (tst) was detected in 82% of isolates. Regarding antimicrobial resistance, twelve strains were susceptible to all the antibiotics tested (31.6%). However, 15.8% were resistant to three or more antimicrobials and, therefore, multidrug-resistant. Our results showed that in general, efficient cleaning and disinfection procedures were applied. Nonetheless, the presence of S. aureus with virulence determinants and resistance to antimicrobials, particularly multidrug-resistant MRSA ST398 strains, might represent a potential health hazard for consumers.

The distribution of log counts at a given time during the exponential growth phase of Listeria innocua measured in food samples inoculated with one cell each was applied to estimate the distribution of the single-cell lag times. Three replicate experiments in broth showed that the distribution of the log counts is a linear mapping of the distribution of the detection times measured by optical density. The detection time distribution reflects the lag time distribution but is shifted in time. The log count distribution was applied to estimate the distributions of the lag times in a liquid dairy product and in liver paté after different heat treatments. Two batches of ca. 100 samples of the dairy product were inoculated and heated at 55°C for 45 min or at 62°C for 2 min, and an unheated batch was incubated at 4°C. The final concentration of surviving bacteria was ca. 1 cell per sample. The unheated cells showed the shortest lag times with the smallest variance. The mean and the variance of the lag times of the surviving cells at 62°C were greater than those of the cells treated at 55°C. Three batches of paté samples were heated at 55°C for 25 min, 62°C for 81 s, or 65°C for 20 s. A control batch was inoculated but not heated. All paté samples were incubated at 15°C. The distribution of the lag times of the cells heated at 55°C was not significantly different from that of the unheated cells. However, at the higher temperatures, 62°C and 65°C, the lag duration was longer and its variance greater.

The influence of applying hydrostatic high pressure (HHP) to red grape pomace cv. Tempranillo was studied to obtain an ingredient rich in bioactive compounds for the manufacture of food products. Four treatments were investigated: (i) 600 MPa/1 s; (ii) 600 MPa/300 s, and other two treatments with 2 cycles of HHP: (iii) 2 cycles of 600 MPa/1 s; and (iv) 1 first cycle of 400 MPa/1 s and a second cycle 600 MPa/1 s. Treated pomace was stored at different temperatures (4 and 20 °C). The application of two consecutive cycles had no effect on the microorganisms’ inactivation compared to only one cycle. Immediately after HHP, the phenolic compounds content was maintained. However, HHP had no influence on the polyphenol oxidase enzyme (PPO), and so the phenolic compounds were significantly reduced during storage. Hence, the shelf-life of red grape pomace was significantly reduced at both temperatures, although phenolic compounds were better preserved under refrigeration than at room temperature.