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Toxoplasma gondii is an important zoonotic foodborne parasite. Meat of infected animals appears to be a major source of infection in Europe. Pork is the most consumed meat in France, with dry sausages well represented. The risk of transmission via consumption of processed pork products is largely unknown, mainly since processing will affect viability but may not entirely inactivate all T. gondii parasites.We investigated the presence and concentration of T. gondii DNA in the shoulder, breast, ham, and heart of pigs orally inoculated with 1000 oocysts (n = 3) or tissue cysts (n = 3) and naturally infected pigs (n = 2), by means of magnetic capture qPCR (MC-qPCR). Muscle tissues of experimentally infected pigs were further used to evaluate the impact of manufacturing processes of dry sausages, including different concentrations of nitrates (0, 60, 120, 200 ppm), nitrites (0, 60, 120 ppm), and NaCl (0, 20, 26 g/kg), ripening (2 days at 16–24 °C) and drying (up to 30 days at 13 °C), by a combination of mouse bioassay, qPCR and MC-qPCR.DNA of T. gondii was detected in all eight pigs, including in 41.7% (10/24) of muscle samples (shoulder, breast and ham) and 87.5% (7/8) of hearts by MC-qPCR. The number of parasites per gram of tissue was estimated to be the lowest in the hams (arithmetic mean (M) = 1, standard deviation (SD) = 2) and the highest in the hearts (M = 147, SD = 233). However, the T. gondii burden estimates varied on the individual animal level, the tissue tested and the parasitic stage used for the experimental infection (oocysts or tissue cysts). Of dry sausages and processed pork, 94.4% (51/54) were positive for T. gondii by MC-qPCR or qPCR, with the mean T. gondii burden estimate equivalent to 31 parasites per gram (SD = 93). Only the untreated processed pork sample collected on the day of production was positive by mouse bioassay.The results suggest an uneven distribution of T. gondii in the tissues examined, and possibly an absence or a concentration below the detection limit in some of them. Moreover, the processing of dry sausages and processed pork with NaCl, nitrates, and nitrites has an impact on the viability of T. gondii from the first day of production. Results are valuable input for future risk assessments aiming to estimate the relative contribution of different sources of T. gondii human infections.

Abstract Epidemiological and experimental evidence indicated that processed meat consumption is associated with colorectal cancer risks. Several studies suggest the involvement of nitrite or nitrate additives via N-nitroso-compound formation (NOCs). Compared to the reference level (120 mg/kg of ham), sodium nitrite removal and reduction (90 mg/kg) similarly decreased preneoplastic lesions in F344 rats, but only reduction had an inhibitory effect on Listeria monocytogenes growth comparable to that obtained using the reference nitrite level and an effective lipid peroxidation control. Among the three nitrite salt alternatives tested, none of them led to a significant gain when compared to the reference level: vegetable stock, due to nitrate presence, was very similar to this reference nitrite level, yeast extract induced a strong luminal peroxidation and no decrease in preneoplastic lesions in rats despite the absence of NOCs, and polyphenol rich extract induced the clearest downward trend on preneoplastic lesions in rats but the concomitant presence of nitrosyl iron in feces. Except the vegetable stock, other alternatives were less efficient than sodium nitrite in reducing L. monocytogenes growth.

BackgroundThe use of omics data for monitoring the microbial flow of fresh meat products along a production line and the development of spoilage prediction tools from these data is a promising but challenging task. In this context, we produced a large multivariate dataset (over 600 samples) obtained on the production lines of two similar types of fresh meat products (poultry and raw pork sausages). We describe a full analysis of this dataset in order to decipher how the spoilage microbial ecology of these two similar products may be shaped differently depending on production parameter characteristics.MethodsOur strategy involved a holistic approach to integrate unsupervised and supervised statistical methods on multivariate data (OTU-based microbial diversity; metabolomic data of volatile organic compounds; sensory measurements; growth parameters), and a specific selection of potential uncontrolled (initial microbiota composition) or controlled (packaging type; lactate concentration) drivers.ResultsOur results demonstrate that the initial microbiota, which is shown to be very different between poultry and pork sausages, has a major impact on the spoilage scenarios and on the effect that a downstream parameter such as packaging type has on the overall evolution of the microbial community. Depending on the process, we also show that specific actions on the pork meat (such as deboning and defatting) elicit specific food spoilers such as Dellaglioa algida, which becomes dominant during storage. Finally, ecological network reconstruction allowed us to map six different metabolic pathways involved in the production of volatile organic compounds involved in spoilage. We were able connect them to the different bacterial actors and to the influence of packaging type in an overall view. For instance, our results demonstrate a new role of Vibrionaceae in isopropanol production, and of Latilactobacillus fuchuensis and Lactococcus piscium in methanethiol/disylphide production. We also highlight a possible commensal behavior between Leuconostoc carnosum and Latilactobacillus curvatus around 2,3-butanediol metabolism.ConclusionWe conclude that our holistic approach combined with large-scale multi-omic data was a powerful strategy to prioritize the role of production parameters, already known in the literature, that shape the evolution and/or the implementation of different meat spoilage scenarios.

Dry fermented sausages are produced worldwide by well-controlled fermentation processes involving complex microbiota including many bacterial and fungal species with key technological roles. However, to date, fungal diversity on sausage casings during storage has not been fully described. In this context, we studied the microbial communities from dry fermented sausages naturally colonized or voluntarily surface inoculated with molds during storage using both culture-dependent and metabarcoding methods. Staphylococci and lactic acid bacteria largely dominated in samples, although some halotolerant genera (e.g., Halomonas, Tetragenococcus, and Celerinatantimonas spp.) were also frequently observed. Fungal populations varied from 7.2 to 9.8 log TFU/cm2 sausage casing during storage, suggesting relatively low count variability among products. Fungal diversity identified on voluntarily inoculated casings was lower (dominated by Penicillium nalgiovense and Debaryomyces hansenii) than naturally environment-inoculated fermented sausages (colonized by P. nalgiovense, Penicillium nordicum, and other Penicillium spp. and sporadically by Scopulariopsis sp., D. hansenii, and Candida zeylanoïdes). P. nalgiovense and D. hansenii were systematically identified, highlighting their key technological role. The mycotoxin risk was then evaluated, and in situ mycotoxin production of selected mold isolates was determined during pilot-scale sausage productions. Among the identified fungal species, P. nalgiovense was confirmed not to produce mycotoxins. However, some P. nordicum, Penicillium chrysogenum, Penicillium bialowienzense, Penicillium brevicompactum, and Penicillium citreonigrum isolates produced one or more mycotoxins in vitro. P. nordicum also produced ochratoxin A during pilot-scale sausage productions using “worst-case” conditions in the absence of biotic competition. These data provide new knowledge on fermented sausage microbiota and the potential mycotoxin risk during storage.

Data in this article provide detailed information on the diversity of bacterial communities present on 576 samples of raw pork or poultry sausages produced industrially in 2017. Bacterial growth dynamics and diversity were monitored throughout the refrigerated storage period to estimate the impact of packaging atmosphere and the use of potassium lactate as chemical preservative. The data include several types of analysis aiming at providing a comprehensive microbial ecology of spoilage during storage and how the process parameters do influence this phenomenon. The analysis includes: the gas content in packaging, pH, chromametric measurements, plate counts (total mesophilic aerobic flora and lactic acid bacteria), sensorial properties of the products, meta-metabolomic quantification of volatile organic compounds and bacterial community metagenetic analysis. Bacterial diversity was monitored using two types of amplicon sequencing (16S rRNA and GyrB encoding genes) at different time points for the different conditions (576 samples for gyrB and 436 samples for 16S rDNA). Sequencing data were generated by using Illumina MiSeq. The sequencing data have been deposited in the bioproject PRJNA522361. Samples accession numbers vary from SAMN10964863 to SAMN10965438 for gyrB amplicon and from SAMN10970131 to SAMN10970566 for 16S.