The objective of this study was to evaluate (eO), a biological time temperature integrator (TTI) as a quality and safety indicator for ground beef packed under modified atmosphere and spiced cooked chicken slices packed under modified atmosphere. Storage trials and challenge tests were thus performed on several batches of the studied food to monitor and model the behavior of Listeria monocytogenes, Salmonella, Staphylococcus aureus and the indigenous food flora. Then, two different prototypes of the TTI (eO) were set and manufactured according to the studied products shelf lives. The TTI evolution with time at static and dynamic temperatures was monitored and modeled. Finally, exposure assessment models were set and used under several realistic storage profiles to assess the distributions of the concentration of the indigenous food flora and the distributions of the increase in the pathogens populations obtained at the end of the product shelf life or at the end point of the TTI, taking into account the TTIs batch variability. Results showed that in case of poor storage conditions, TTI can reduce the consumer exposure to altered or hazardous foods.
Portuguese chouriço de vinho is made by drying coarsely minced meat and fat that has been previously marinated with wine (usually red), salt, and garlic for 1 to 2 days at a low temperature (4 to 8 °C). This procedure may improve the microbiological safety of the product. The aim of this study was to evaluate the behavior of three pathogens in this product, Salmonella spp., Listeria monocytogenes, and Staphylococcus aureus, to establish the minimum period of drying and maturation necessary to render safe products. The pathogens were inoculated in the chouriço de vinho batter. A factorial design was used to study the following variables in the fermentation process: (i) the presence or absence of an indigenous Lactobacillus sakei starter culture; (ii) the presence or absence of fermentable carbohydrates; and (iii) the salt level (1.5 or 3%). The samples were analyzed 24 h after the preparation of the batter (at stuffing); after 7, 15, and 30 days of drying; and after 30 days of storage at 4 °C under vacuum. Under all of the conditions studied, the levels of the three pathogens decreased during the drying period. In the early stages of drying, the addition of L. sakei starter culture and/or carbohydrates resulted in lower levels of gram-positive pathogens. After 15 days of drying, populations of all pathogens decreased by ca. 2 log in all samples. At that sampling time, L. monocytogenes was undetectable in the chouriço de vinho with L. sakei starter culture and carbohydrates. The mean count of S. aureus after 15 days of drying was below 1 log CFU/g. After 30 days of drying, no pathogens were detected. The drying period could be shortened to 15 days when considering only the gram-positive pathogens studied and the use of a starter culture and carbohydrates. Due to the low infective dose of Salmonella spp., the product should be considered safe after 30 days, when this pathogen became undetectable.
The objective of this paper is to compare the cost-effectiveness of four decontamination technologies at the pork abattoirs. The four technologies investigated are hot water, steam ultrasound, steam vacuum and lactic acid. In the analysis, the prevalence of Salmonella and the effects of the decontaminating technologies are stochastic with known distributions and they are expected to be implemented without distortion of the existing processing system. Cost data are collected from the Danish Meat Research Institute, suppliers of decontamination technology, abattoirs using the technology as well as the literature. The risk data are based on Danish surveillance data, research projects investigating the effects of different decontamination measures and the literature. Implemented on a full scale in abattoirs, the results suggest that the technologies might reduce Salmonella from the present level of 2.2% to between 0.18 and 0.89%. Among the technologies investigated, steam ultrasound showed to be the most cost-effective method followed by hot water decontamination.
During the last two decades the major food safety problems in Denmark, as determined by the number of human patients, has been associated with bacterial infections stemming from meat products and eggs. The bacterial pathogens causing the majority of human infections has been Salmonella and Campylobacter, and to a lesser extent Yersinia, Escherichiacoli O157 and Listeria. Danish initiatives to improve the safety of meat products have focused on the entire production chain from the farm to the consumer, with a special emphasis on the pre-harvest stage of production. The control of bacterial pathogens which are resistant to antibiotics has been a new area of attention in the recent decade, and recently, the increasing globalization of the domestic food supply has called for a complete rethinking of the national food safety strategies. The implementations of a "case-by-case" risk assessment system, as well as increased international collaboration on surveillance, are both elements in this new strategy.
A novel extension of traditional growth models for exposure assessment of food-borne microbial pathogens was developed to address the complex interactions of competing microbial populations in foods. Scenarios were designed for baseline refrigeration and mild abuse of servings of chicken broiler and ground beef Our approach employed high-quality data for microbiology of foods at production, refrigerated storage temperatures, and growth kinetics of microbial populations in culture media. Simple parallel models were developed for exponential growth of multiple pathogens and the abundant and ubiquitous nonpathogenic indigenous microbiota. Monte Carlo simulations were run for unconstrained growth and growth with the density-dependent constraint based on the "Jameson effect," inhibition of pathogen growth when the indigenous microbiota reached 10(9) counts per serving. The modes for unconstrained growth of the indigenous microbiota were 10(8), 10(10), and 10(11) counts per serving for chicken broilers, and 10(7), 10(9) and 10(11) counts per serving for ground beef at respective sites for backroom, meat case, and home refrigeration. Contamination rates and likelihoods of reaching temperatures supporting growth of the pathogens in the baseline refrigeration scenario were rare events. The unconstrained exponential growth models appeared to overestimate L. monocytogenes growth maxima for the baseline refrigeration scenario by 1500-7233% (10(6)-10(7) counts/serving) when the inhibitory effects of the indigenous microbiota are ignored. The extreme tails of the distributions for the constrained models appeared to overestimate growth maxima 110% (10(4)-10(5) counts/serving) for Salmonella spp. and 108% (6 x 10(3) counts/serving) for E. coli O157:H7 relative to the extremes of the unconstrained models. The approach of incorporating parallel models for pathogens and the indigenous microbiota into exposure assessment modeling motivates the design of validation studies to test the modeling assumptions, consistent with the analytical-deliberative process of risk analysis.
The role of indigenous microflora of a finished compost, defined NK12, on the growth suppression of pathogens under different moisture and temperature storages was investigated. Total count of mesophilic and thermophilic bacteria was evaluated by the most probable number method and growth of seeded Salmonella arizonae 3924 serogroup B and enteropathogenic Escherichia coli 84 M in NK12 at different moisture temperature conditions was monitored. Results on sterile and non-sterile NK12 were compared. In all tested experimental conditions, the NK12 indigenous microflora was stable and biologically active. S. arizonae 3924 and E. coli 84 M grew rapidly in sterilized NK12 at different moistures and storage temperatures, and their growth was suppressed in non-sterilized NK12. Pathogens inactivation was lower when compost was stored at 40% and 80% humidity and at 37 degrees C. Our results show that the major role in the pathogens suppression was played by the indigenous microflora of the finished compost, although physical factors too influenced the growth phenomenon.
Previously there was no available information on the levels of indicator bacteria and the prevalence of pathogens in fresh produce grown in Alberta, Canada. Baseline information on the occurrence and levels of Escherichia coli and the prevalence of foodborne pathogens in selected produce items available to consumers from farmers' and public markets in two large urban centers and surrounding areas in Alberta was obtained. A total of 10 large markets with between 1 and 12 produce vendors and 26 small markets with between 1 and 6 produce vendors were sampled from 21 June to 7 October 2007. Lettuce (128 samples), spinach (59 samples), tomatoes (120 samples), carrots (206 samples), green onions (129 samples), and strawberries (31 samples) were analyzed for E. coli, Salmonella, E. coli O157:H7, and Campylobacter spp. Lettuce, spinach, green onion, and strawberry samples were also tested for the presence of Cryptosporidium spp. Information on whether produce was grown using organic or conventional practices was obtained from the produce vendors. E. coli was isolated from 8.2% of the samples that included lettuce, spinach, carrots, and green onions. The bacterial counts ranged from 3.04 Log most probable number per g. E. coli was not isolated from tomatoes or strawberries. The percentage of positive samples ranged from 4.4% for carrots to 27.1% for spinach. Salmonella, E. coli O157:H7, and Campylobacter spp. were not isolated from any of the samples. Cryptosporidium was identified by PCR in one sample of spinach (0.6% of the samples).
This study addressed health risks from ethnic sausages produced on a small scale, without inspection, in California and elsewhere. Mexican-style chorizo, a raw pork sausage that is not cured, fermented, or smoked, was contaminated experimentally in the batter with Escherichia coli O157:H7, Listeria monocytogenes, or Salmonella serotypes and stuffed into natural casings. Formulations were based on a market survey in California. Physical parameters that were controlled were pH, water activity (a(w)), and storage temperature. The pH was adjusted with vinegar, stabilizing at 5.0 within 24 h. Initial a(w) levels adjusted with salt were 0.97, 0.95, 0.93, 0.90, and 0.85; levels declined with time because of evaporation. Pathogen numbers declined with storage up to 7 days, with few brief exceptions. Main effects and interactions of constant temperature and pH with declining a(w) on survival of the pathogens were determined. Maximum death rates occurred at higher a(w) for E. coli O157:H7 and Salmonella than for L. monocytogenes. Salt used to adjust a(w) affected palatability. Spices (black pepper, chili pepper, chili powder, cumin, garlic, guajillo pepper, oregano, and paprika) comprised another, potentially significant aspect of the sausage formulation. Some (notably black pepper and cumin) carried an indigenous microflora that contributed significantly to the microbial load of the sausage batter. Only undiluted fresh and powdered garlic exhibited a significant antimicrobial effect on the pathogens. Although each of the tested formulations caused death of the inoculated pathogens, none of the death rates was sufficiently rapid to ensure safety within the probable shelf life of the product.
The objective of this study was to estimate the prevalence of Salmonella on raw retail chicken meat in Russia. Broiler chicken carcasses (n = 698) were collected from three regions of Russia: central (i.e., Moscow area), northwest (i.e., St. Petersburg area), and southern (i.e., Krasnodar area). In each region, samples were collected to represent various cities and districts, as well as different types of retail stores and carcass storage temperatures (i.e., chilled and frozen). All chicken samples were analyzed for the presence of Salmonella using a whole-carcass rinse method. The overall Salmonella prevalence was 31.5%. There were significant differences (P
In order to study the public health effects of the Finnish Salmonella control program (FSCP), a quantitative risk assessment model of Salmonella from slaughtered broiler flocks to consumers was developed. Based on the model, approximately 0.21% of domestically produced broiler meat mass was contaminated with Salmonella (95% probability interval 0.05-0.48%). This model was combined to the model on primary production of broilers. By this way, the effect of eliminating breeder flocks from production which have tested positive for Salmonella and heat-treating the meat of detected positive broiler flocks on public health could be simulated. Based on the whole model, if detected positive breeder flocks were not removed this would result in 1.0-2.5 more reported human cases compared to the expected number of cases under current FSCP (95% predictive interval). Without heat treatment of meat the increase would be 2.9-5.4-fold and without both interventions 3.8-9.0-fold. In scenarios with one grandparent or five parent flocks infected, the combined effect of these two interventions was 9.3-25.8-fold and 4.9-11.7-fold compared to the baseline level under each scenario, respectively. The scenario analyses suggest that with a higher infection level, inclusion of both interventions will be more effective than either of the interventions alone. Replacement of half of the current retail broiler meat by meat with 20-40% contamination could result in 33-93 times more human cases compared to the expected value under current situations. On the basis of the model, the interventions applied in FSCP clearly protect the public health.