Development and validation of GC/MS method for simultaneous determination of 16 polycyclic aromatic hydrocarbons (PAHs) in pork meat matrix

The major processes for introducing polycyclic aromatic hydrocarbons (PAHs) in food are smoking and grilling of different products. But in addition, PAHs can permeate in the food chain due to their high lipophilicity and ability to be accumulated in specific tissue, through contaminated animal feed. Further, when some parts of these animals are marketed as food, the accumulated PAHs can go to the human organism. Some of them are classified as highly toxic, carcinogenic and mutagenic for animal and human organisms so they are under consideration of International and European legislation. This work reports development and validation of simple and fast GC/MS method for 16 PAHs determination. Comparison of two methods for sample preparation in pork meat matrix standard extraction/saponification procedure and modified QuEChERS method is also done. In addition, this paper report the calibration step of instrument and a recovery study for 16 PAHs in model pork meat, using modified QuEChERS procedure for sample pretreatment. The calibration step with accessible and suitable for use in real laboratory conditions internal standard (chrysene D12) is done in the range 10–100 ppb using toluene as solvent. The obtained results show very good linearity (R2 = 0.99 to 1.00). For the recovery study six model samples were spiked with 16 PAHs and they all are subjected to QuEChERS procedure. The recovery is calculated and the obtained data (71–120%) is in a good correlation with requirements of international legislation. Finally, LOD values for all 16 investigated compounds of modified GC/MS method and for the instrument were determined.

Meta-analysis of Campylobacter spp. Survival Data within a Temperature Range of 0 to 42°C

In Europe, Campylobacter is the leading reported cause of bacterial foodborne infectious disease. Quantifying its ability to survive at chilled and ambient temperatures and identifying the factors involved in variation in its survival may contribute to the development of efficient risk management strategies. A data set of 307 inactivation curves collected from the literature and the ComBase database, combined with 388 experimental curves, was analyzed with a log-linear model to obtain 695 D-values (time for 1 log inactivation). An additional 146 D-values collected from the literature or ComBase were added to the data set, for a total of 841 D-values. Because data were collected from different studies, the experimental conditions were somewhat heterogeneous (e.g., type of media or strain used). The full data set was then split into 19 different study types on which a meta-analysis was performed to determine the effect of temperature (range 0 to 42°C), Campylobacter species (C. coli and C. jejuni), and media (liquid media or meat matrix) on the survival ability of Campylobacter. A mixed-effects model, in which the study type and bacterial species were considered as random effects and the media and temperature as fixed effects, was run using a Bayesian approach. Overall, the model gave satisfactory results, with a residual standard deviation of 0.345 (the model response was the log D-value, expressed in days). In addition, the survival of Campylobacter was greater at 0 than at 42°C, with a log-linear pattern; the z-value (temperature to have a 10-fold decrease of D-value) was estimated to be 26.4°C (95% interval: 23.9 to 29.4°C). Despite a significant media-species interaction term, it was established that both species were more resistant on the meat matrix than in liquid media. These results may be used to understand how Campylobacter can survive along the food chain, particularly in chilled environments, and consequently be transferred to other foodstuffs.

Effects of Suspension in Emulsified Wiener or Incubation in Wiener Packages on the Virulence of Listeria monocytogenes Scott A in Intragastrically Inoculated A/J Mice†

Several outbreaks of listeriosis have been associated with contamination of wieners and other ready-to-eat meat products. In this study, we addressed the question of whether emulsification in, or growth on, wieners triggers a response in the listerial cells that makes them more virulent or protects them against the harsh environment of the gastrointestinal tract in mice. Our results indicate that Listeria monocytogenes Scott A grows poorly, if at all, in one brand of commercially prepared wieners inoculated with 5 × 103 to 5 × 106 CFU per package and incubated at 15°C. Neither L. monocytogenes Scott A emulsified in a slurry of homogenized wieners nor recovered from wiener package fluid after a 7-day incubation at 15°C were more virulent when inoculated into the stomachs of A/J mice than L. monocytogenes Scott A grown in brain heart infusion broth. These findings suggest that the ability of L. monocytogenes Scott A to cause systemic infection following introduction into the gastrointestinal tract was not improved by incubation with wieners or suspension in a meat matrix.