Search Results (9)

Listeria monocytogenes is a foodborne pathogen capable of contaminating ready-to-eat meat products, e.g., frankfurters. Post-packaging mild heat treatment via water immersion is commonly employed; however, this may be sublethal to cells located in protected niches or beneath the product surface. The objectives of this study were to evaluate thermal injury of L. monocytogenes on frankfurters at single-cell versus population level and to comparatively estimate pathogens’ physiological status. Pork frankfurter-type sausages were inoculated (ca. 7.0–7.5 log CFU/cm²) with L. monocytogenes strain EGDE-e. Heat treatment was performed at 61 °C (max. 60 min) and 64 °C (max. 12 min). To determine the injured subpopulation from the total, tryptic soy agar with 0.6% yeast extract (TSAYE), supplemented or not with 5% NaCl, was used. Plating-based quantification of injured cells was compared to CFDA/PIstained cells analysed by fluorescence microscopy and quantified with Fiji software. Injury was recorded mainly after 2 and 4 min at 64 °C, whereas no injury was detected at 61 °C, at population level. Following exposure to 61 °C for 60 min, culturable cells dropped below the enumeration limit (0.3 log CFU/cm²), while a considerable number of CFDA⁺/PI⁻ and CFDA⁺/PI⁺ cells indicated viable-but-non-culturable induction and sublethal injury, respectively. These findings suggest that non-culturability may limit the accuracy of solely culture-based enumeration methods. Full article

Non-typhoidal salmonellosis is a foodborne disease caused by Salmonella spp. Most outbreaks of this disease are commonly associated with consuming contaminated meat products, hence the importance of monitoring ready-to-eat artisanal pork sausages for the presence of these bacteria. A total of 494 samples of grilled and smoked barbecue artisanal pork sausages were collected at food outlets from 12 municipalities of the Department of Quindío, Colombia, between 2017 and 2022. Salmonella spp. was identified using VIDAS^® Easy SLM and confirmed through API^® 20 E. Salmonella spp. was detected in 260 samples (52.6%), and the highest rates of contamination were found in Armenia (65.7%), Salento (65.2%), Circasia (57.7%), and Calarcá (56.4%). The highest proportion of these samples positive for Salmonella spp. was ready-to-eat smoked barbecue artisanal sausages (68.8%) sold by street vendors (58.4%) from 12 municipalities of the Department of Quindío. A significant association was observed between the municipality and contamination of samples with Salmonella spp. However, no link was found between the sampling year and the presence of the bacteria. This is the first study aimed at monitoring the presence of Salmonella spp. in artisanal pork sausages sold in the municipalities of the Department of Quindío over a 6-year period, and findings revealed very high percentages of contamination. Although Colombian legislation establishes sanitary and safety requirements for meat production, the presence of Salmonella spp. in artisanal sausages remains a persistent public health threat in developing countries. Full article

Antimicrobial resistance is an existential threat to the health sector, with far-reaching consequences in managing microbial infections. In this study, one hundred and ninety-four Listeria monocytogenes isolates were profiled for susceptibility using disc diffusion techniques. Possible foodborne listeriosis risk associated with ready-to-eat (RTE) foods (RTEF) and the risk of empirical treatment (EMPT) of L. monocytogenes infections, using multiple antimicrobial resistance indices (MARI) and antimicrobial resistance indices (ARI), respectively, were investigated. Twelve European Committee on Antimicrobial Susceptibility Testing (EUCAST) prescribed/recommended antimicrobials (EPAS) for the treatment of listeriosis and ten non-prescribed antimicrobials (non-PAS)] were evaluated. Antimicrobial resistance > 50% against PAs including sulfamethoxazole (61.86%), trimethoprim (56.19%), amoxicillin (42.27%), penicillin (41.24%), and erythromycin (40.21%) was observed. Resistance > 50% against non-PAS, including oxytetracycline (60.89%), cefotetan (59.28%), ceftriaxone (53.09%), and streptomycin (40.21%) was also observed. About 55.67% and 65.46% of the isolates had MARI scores ranging from 0.25–0.92 and 0.30–0.70 for EPAs and non-PAs, respectively. There was a significant difference (p < 0.01) between the MARI scores of the isolates for EPAs and non-PAs (means of 0.27 ± 0.21 and 0.31 ± 0.14, respectively). MARI/ARI scores above the Krumperman permissible threshold (>0.2) suggested a high risk/level of antimicrobial-resistant L. monocytogenes. The MARI risks of the non-success of empirical treatment (EMPT) attributed to EPAs and non-PAs were generally high (55.67% and 65.463%, respectively) due to the antimicrobial resistance of the isolates. MARI-based estimated success and non-success of EMPT if EUCAST-prescribed antimicrobials were administered for the treatment of listeriosis were 44.329% and 55.67%, respectively. The EMPT if non-prescribed antimicrobials were administered for the treatment of listeriosis was 34.53% and 65.46%, respectively. This indicates a potentially high risk with PAs and non-PAs for the treatment of L. monocytogenes infection. Furthermore, ARI scores ≤ 0.2 for EPAs were observed in polony, potato chips, muffins, and assorted sandwiches, whereas ARI scores for non-PAs were >0.2 across all the RTE food types. The ARI-based estimate identified potential risks associated with some RTE foods, including fried fish, red Vienna sausage, Russian sausage, fruit salad, bread, meat pies, fried chicken, cupcakes, and vetkoek. This investigation identified a high risk of EMPT due to the presence of antimicrobial-resistant L. monocytogenes in RTE foods, which could result in severe health consequences. Full article

Ready-to-eat meat products have been identified as a potential vehicle for Listeria monocytogenes. Postprocessing contamination (i.e., handling during portioning and packaging) can occur, and subsequent cold storage together with a demand for products with long shelf life can create a hazardous scenario. Good hygienic practice is augmented by intervention measures in controlling post-processing contamination. Among these interventions, the application of ‘cold atmospheric plasma’ (CAP) has gained interest. The reactive plasma species exert some antibacterial effect, but can also alter the food matrix. We studied the effect of CAP generated from air in a surface barrier discharge system (power densities 0.48 and 0.67 W/cm²) with an electrode-sample distance of 15 mm on sliced, cured, cooked ham and sausage (two brands each), veal pie, and calf liver pâté. Colour of samples was tested immediately before and after CAP exposure. CAP exposure for 5 min effectuated only minor colour changes (ΔE max. 2.7), due to a decrease in redness (a*), and in some cases, an increase in b*. A second set of samples was contaminated with Listeria (L.) monocytogenes, L. innocua and E. coli and then exposed to CAP for 5 min. In cooked cured meats, CAP was more effective in inactivating E. coli (1 to 3 log cycles) than Listeria (from 0.2 to max. 1.5 log cycles). In (non-cured) veal pie and calf liver pâté that had been stored 24 h after CAP exposure, numbers of E. coli were not significantly reduced. Levels of Listeria were significantly reduced in veal pie that had been stored for 24 h (at a level of ca. 0.5 log cycles), but not in calf liver pâté. Antibacterial activity differed between but also within sample types, which requires further studies. Full article

The aim of this study was to model the effect of annatto (Bixa orellana) extract against S. aureus (SA) in a Portuguese non-ready-to-eat meat product (alheira sausage) during maturation. Alheira batter was prepared with 0.0%, 0.5%, 1.0%, or 1.5% of lyophilised annatto extract and stuffed in pre-washed natural casings following inoculation with SA, then hung in a climatic-controlled chamber at 10 °C for 13 days. For every treatment, a dynamic model was adjusted and adequately fitted to all survival curves with residuals and root mean square errors between 0.0008–0.0016 and 0.029–0.040, respectively, producing significant parameter estimates. Therefore, the addition of annatto extracts significantly shortened the shoulder phase and decreased the time to achieve one log reduction, which, in practical terms, corresponded to up to 1.35 [SE = 0.08] log CFU/g reduction by the end of the 13-day maturation. Full article

The objective of this study was to assess the effect of sage (Salvia officinalis L.) extract on the survival of Staphylococcus aureus in a Portuguese non-ready-to-eat meat product (alheira sausage). Alheira batter was produced, mixed with 0.0%, 0.5%, 1.0%, or 1.5% of lyophilised sage extract, and stuffed in natural casings. Sausages were then individually inoculated with S. aureus and left to ferment/mature at 10 °C/85% RH for 10 days. Sage extract was found to inactivate S. aureus (p < 0.001) with no significant differences between doses. At the 10th day of maturation, S. aureus decreased in 1.146 log CFU/g (SE = 0.065 log CFU/g) in alheiras mixed with 0.5–1.0% sage extract. Nonetheless, this extract retarded the growth of indigenous lactic acid bacteria during maturation. The higher the dose, the greater the effect (p < 0.001). Full article

The microwave oven has become a standard appliance to reheat or cook meals in households and convenience stores. However, the main problem of microwave heating is the non-uniform temperature distribution, which may affect food quality and health safety. A three-dimensional mathematical model was developed to simulate the temperature distribution of four ready-to-eat sausages in a plastic package in a stationary versus a rotating microwave oven, and the model was validated experimentally. COMSOL software was applied to predict sausage temperatures at different orientations for the stationary microwave model, whereas COMSOL and COMSOL in combination with MATLAB software were used for a rotating microwave model. A sausage orientation at 135° with the waveguide was similar to that using the rotating microwave model regarding uniform thermal and electric field distributions. Both rotating models provided good agreement between the predicted and actual values and had greater precision than the stationary model. In addition, the computational time using COMSOL in combination with MATLAB was reduced by 60% compared to COMSOL alone. Consequently, the models could assist food producers and associations in designing packaging materials to prevent leakage of the packaging compound, developing new products and applications to improve product heating uniformity, and reducing the cost and time of the research and development stage. Full article

Alheira is a traditional non-ready-to-eat sausage produced mainly in northern Portugal. The objective of this study was to evaluate the associations between some relevant physicochemical and microbiological attributes of alheiras produced by different regional producers. Finished products from 8 regional factories amounting to 40 samples were analyzed. Counts of mesophiles, lactic acid bacteria, Staphylococcus aureus, presumptive Clostridium perfringens, and Salmonella spp., as well as pH, water activity (a_W), and proximate analysis were determined. Principal component analysis (PCA) of these variables was conducted to construct quality maps. Three meaningful components were extracted, accounting for 63% of data variability. PC1 (26% data variability) was positively associated with LAB, mesophiles, and S. aureus, characterizing therefore longer fermentation. PC2 (22% data variability) correlated negatively with moisture, a_W and positively with C. perfringens, and thus has been linked to greater dehydration of sausages. PC3 (15% data variability) correlated positively with pH and protein content, implying the use of more meat in the formulation. This preliminary work has identified three quality factors underpinning the variability in artisanal alheiras; and has also highlighted the need to implement better microbiological control and process standardization during the production of artisanal alheiras. Full article

Although conventional microbial control techniques are currently employed and largely successful, their major drawbacks are related to their effects on quality of processed food. In recent years, there has been a growing demand for high-quality foods that are microbially safe and retain most of their natural freshness. Therefore, several modern and innovative methods of microbial control in food processing have been developed. High-hydrostatic-pressure (HHP) processing technology has been mainly used to enhance the food safety of ready-to-eat (RTE) products as a new pre-/post-packaging, non-thermal purification method in the meat industry. Listeria monocytogenes is a pertinent target for microbiological safety and shelf-life; due to its capacity to multiply in a broad range of food environments, is extremely complicated to prevent in fermented-sausage-producing plants. The frequent detection of L. monocytogenes in final products emphasizes the necessity for the producers of fermented sausages to correctly overcome the hurdles of the technological process and to prevent the presence of L. monocytogenes by applying novel control techniques. This review discusses a collection of recent studies describing pressure-induced elimination of L. monocytogenes in fermented sausages produced in the Mediterranean area. Full article