Microbiological quality of ready-to-eat foods: results from a long-term surveillance program (1995 through 2003)

Microbiological Profile and Hygienic Quality of Foodstuffs Marketed in Collective Catering in Central Morocco

Food hygiene is important both for its impact on the health of citizens and also for the cost of the infections that it can generate. In Morocco, it has become a concern of authorities. This work, realized for the first time in the center of Morocco, is aimed at describing the microbiological quality of foodstuffs marketed in collective catering in central Morocco. This study was conducted retrospectively from January 2015 to December 2019 in Fez city, central Morocco. The samples collected by the competent authority during official control from restaurants and food outlets were analyzed. Non-conformity was chosen as an indicator of food quality according to the official Moroccan standards. The samples were presented according to several variables: year/month/season, category/subcategory, communes, and establishment. The statistical processing of the results was done by SPSS 25. The Chi2 statistical test was calculated to determine a relationship between non-conformity and the type of analyzed matrix (year, season, and food category). The test was considered statistically significant for a p value < 0.05. A total of 2223 food samples were investigated, with an annual average of 445 samples. Overall, the rate of non-compliance during 2015-2019 was 31%, reaching its maximum in 2017 (36.4%) and its minimum in 2018 (27.5%).This rate varies by food type. Juices/drinks and meat products are the most contaminated with 71.7% and 58.1%, respectively, followed by milk and derivatives with 43.2%, seasoning sauces with 28.6%, pastries and pastry creams with 21.4%, and 14.4% for ready meals. The main causes of food non-conformity were fecal contamination germs with 67% positive fecal coliforms and 15% of total coliforms followed by total germs (7%), Staphylococcus aureus (5%), yeasts and molds (3%), sulfite-reducing anaerobes (2%), and Salmonella (1%). Given the obtained results, improving the hygienic quality of foods is necessary to ensure better consumer safety.

Antimicrobial Resistance in the Food Chain: Trends, Mechanisms, Pathways, and Possible Regulation Strategies

Antimicrobial resistance (AMR) remains of major interest for different types of food stakeholders since it can negatively impact human health on a global scale. Antimicrobial-resistant bacteria and/or antimicrobial resistance genes (transfer in pathogenic bacteria) may contaminate food at any stage, from the field to retail. Research demonstrates that antimicrobial-resistant bacterial infection(s) occur more frequently in low- and middle-income countries (LMICs) than in developed countries. Worldwide, foodborne pathogens are a primary cause of morbidity and mortality. The spread of pathogenic bacteria from food to consumers may occur by direct or indirect routes. Therefore, an array of approaches both at the national and international level to control the spread of foodborne pathogens and promote food safety and security are essential. Zoonotic microbes can spread through the environment, animals, humans, and the food chain. Antimicrobial drugs are used globally to treat infections in humans and animals and prophylactically in production agriculture. Research highlights that foods may become contaminated with AMR bacteria (AMRB) during the continuum from the farm to processing to retail to the consumer. To mitigate the risk of AMRB in humans, it is crucial to control antibiotic use throughout food production, both for animal and crop agriculture. The main inferences of this review are (1) routes by which AMRB enters the food chain during crop and animal production and other modes, (2) prevention and control steps for AMRB, and (3) impact on human health if AMR is not addressed globally. A thorough perspective is presented on the gaps in current systems for surveillance of antimicrobial use in food production and/ or AMR in the food chain.

Microbiological Safety of Ready-to-Eat Foods in Hospital and University Canteens in Hanoi, Vietnam

ABSTRACT

The aim of this study was to analyze and document the microbiological safety and quality of ready-to-eat foods in hospital and university canteens in Hanoi, Vietnam. In total, 420 ready-to-eat food products from 21 canteens were sampled in July 2018 and May 2019. The ratio of samples exceeding the unsatisfactory level for total plate count was 31%. Escherichia coli, Listeria, and Staphylococcus aureus were detected in 35 (8.3%), 99 (24%), and 46 (11%) samples, with 3, 10, and 0% exceeding the unsatisfactory level, respectively. The total plate count, Listeria, Bacillus cereus, E. coli, and S. aureus ranged from below detection limit to 5 × 109, 4.6 × 105, 6.2 × 103, 3.4 × 103, and 7.6 × 103 CFU/g, respectively. L. monocytogenes was isolated from 3 (0.7%) of 420 samples. In addition, 21 (5%) of 410 samples were contaminated with Salmonella. Overall, our data indicate frequent problems with the microbiological quality and safety of these canteen foods in Hanoi and provide a baseline measurement that will allow environmental health officers and food microbiologists to develop targeted intervention strategies to reduce the economic and public health risk associated with these foods.

HIGHLIGHTS

A review of chemical and microbial contamination in food: What are the threats to a circular food system?

A circular food system is one in which food waste is processed to recover plant nutrients and returned to the soil to enable the production of more food, rather than being diverted to landfill or incineration. The approach may be used to reduce energy and water use in food production and contribute to the sustainability of the system. Anaerobic digestion and composting are common food waste treatment technologies used to stabilize waste and produce residual materials that can replenish the soil, thus contributing to a circular food system. This approach can only be deemed safe and feasible, however, if food waste is uncontaminated or any contaminants are destroyed during treatment. This review brings together information on several contaminant classes at different stages of the food supply chain, their possible sources, and their fates during composting and digestion. The main aim is to identify factors that could impede the transition towards a safe, reliable and efficient circular food system. We investigated heavy metals, halogenated organic compounds, foodborne pathogens and antibiotic resistance genes (ARGs) in the food system and their fates during digestion and composting. Production and processing stages were identified as major entry points for these classes of contaminants. Heavy metals and foodborne pathogens pose less risk in a circular system than halogenated organics or antibiotic resistance. Given the diversity of properties among halogenated organic compounds, there is conflicting evidence about their fate during treatment. There are relatively few studies on the fate of ARGs during treatment, and these have produced variable results, indicating a need for more research to clarify their fate in the final products. Repeated land application of contaminated food waste residuals can increase the risk of accumulation and jeopardize the safety of a circular food system. Thus, careful management of the system and research into the fate of the contaminants during treatment is needed.

Microbiological Quality of Foodstuffs Sold on Expiry Date at Retail in Portugal: A Preliminary Study

Currently, food waste represents an important issue due to its negative economic, social and environmental impact. To reduce the food waste levels, some retailers’ brands implement discounting based on the proximity to expiry. Since this practice may involve potential food poisoning, a total of 94 food products from animal origin, purchased in two supermarkets in North Portugal on the expiry date, were analyzed for selected foodborne and spoilage microorganisms. Moreover, the samples were classified as satisfactory and not satisfactory according to their microbiological quality. The results showed that none of the samples presented counts for Salmonella spp., S. aureus, B. cereus. L. monocytogenes was detected in one sample over the limit of 2 log cfu/g as defined by Regulation 2073/2005. The evaluation of food hygiene and spoilage indicators showed that the processed foods displayed lower counts than raw products (beef, pork, chicken and fish). Regarding Enterobacteriaceae, raw products presented on average over 2 log cfu/g than processed foods, with the exception of beef samples that accounted over 3 log cfu/g more than processed foods. In addition, E. coli was mainly detected in fresh meat of which chicken and pork displayed the highest counts. Regarding the qualitative classification, 51.06% of the samples were not satisfactory for the total mesophilic counts, while 62.76% and 58.51% displayed positive results for Enterobacteriaceae and molds and yeasts (M&Y) criteria, respectively. In all, 70.21% of the samples analyzed at the expiry date failed, at least, in one microbiological criterion. The results indicate that the foods available at the end of the shelf life in supermarkets do not represent a risk for food poisoning due to the absence of foodborne pathogens. Since the microbiological indicators of storage/handling of raw products were mainly unsatisfactory, this indicates that the sale of these perishable foods at the end of the shelf life may not be recommended. On the other hand, processed products subjected to food conservation procedures (i.e., thermal processing) could be sold at the end of their shelf life or donated beyond the best-before date, due to its physical, chemical and microbiological stability. However, evidences of foodborne outbreaks associated to this kind of foodstuffs indicated the need of a proper risk assessment. Moreover, it is important to remark that other factors such as small sample size, the absence of the evaluation of the handling, and storage conditions along the food chain or organoleptic alterations must be assessed in further studies.

Risk presented to minimally processed chilled foods by psychrotrophic Bacillus cereus

BACKGROUND

Spores of psychrotrophic Bacillus cereus may survive the mild heat treatments given to minimally processed chilled foods. Subsequent germination and cell multiplication during refrigerated storage may lead to bacterial concentrations that are hazardous to health.

SCOPE AND APPROACH

This review is concerned with the characterisation of factors that prevent psychrotrophic B. cereus reaching hazardous concentrations in minimally processed chilled foods and associated foodborne illness. A risk assessment framework is used to quantify the risk associated with B. cereus and minimally processed chilled foods.

KEY FINDINGS AND CONCLUSIONS

Bacillus cereus is responsible for two types of food poisoning, diarrhoeal (an infection) and emetic (an intoxication); however, no reported outbreaks of food poisoning have been associated with B. cereus and correctly stored commercially-produced minimally processed chilled foods. In the UK alone, more than 1010 packs of these foods have been sold in recent years without reported illness, thus the risk presented is very low. Further quantification of the risk is merited, and this requires additional data. The lack of association between diarrhoeal food poisoning and correctly stored commercially-produced minimally processed chilled foods indicates that an infectious dose has not been reached. This may reflect low pathogenicity of psychrotrophic strains. The lack of reported association of psychrotrophic B. cereus with emetic illness and correctly stored commercially-produced minimally processed chilled foods indicates that a toxic dose of the emetic toxin has not been formed. Laboratory studies show that strains form very small quantities of emetic toxin at chilled temperatures.

The prevalence of Campylobacter spp. in vegetables, fruits, and fresh produce: a systematic review and meta-analysis

There are a number of reports indicating correlation between outbreaks of campylobacteriosis and the consumption of raw vegetables. This study is a meta-analysis on the prevalence of Campylobacter in fresh vegetables and fruits without any location limitation, which was performed through a documented review of the available resources. Relevant literature was reviewed by trained reviewers, who examined the results for the inclusion of articles in the meta-analysis. The prevalence of Campylobacter in raw vegetables, the sample source, the Campylobacter species, and the method of detection were extracted. The prevalence of Campylobacter in vegetables, fruits, and fresh produce were estimated to be 0.53%. Analysis of the various sample groups initially showed that the bean and sprouts group was the vegetable with the highest prevalence of Campylobacter (11.08%). The rate of contamination was higher when both the molecular and conventional methods were employed. The highest prevalence of Campylobacter was found in Asia (33.4%). Despite the low prevalence, consumption of raw vegetables is inherently risky because no treatment is used to inactivate the pathogens. Therefore, proper sanitation methods are recommended to treat the raw products.

Microbiological Survey of Packaged Ready-to-Eat Red Meats at Retail in New Zealand

A microbiological survey was undertaken on packaged ready-to-eat red meats available at retail in New Zealand. A total of 1,485 samples (297 lots of five samples each) were collected according to a sampling plan based on market share and regulatory regimes (Animal Products Act 1999 and Food Act 1981) and were tested against the microbiological limits specified in Food Standards Code (FSC) 1.6.1 applicable at the time of sampling. Each lot was tested as a composite for the presence or absence of Salmonella spp., coagulase-producing staphylococci, Listeria monocytogenes, and other Listeria spp. at the end of the manufacturer's stated shelf life. Individual samples within a positive lot were subsequently enumerated for L. monocytogenes. None of the samples contained Salmonella spp. or had coagulase-producing staphylococci counts above the acceptable level specified in FSC 1.6.1 (>100 CFU/g). Data showed that 93.6% (278 of 297 lots) of ready-to-eat red meat complied with the FSC 1.6.1 criteria applicable at the time of the survey. The failure of 19 lots (6.4%) was due to the presence of L. monocytogenes from product obtained from 8 of 33 producers tested. Thirteen samples of 95 positive samples were found to contain between 50 and 500 CFU/g L. monocytogenes, but all of these samples were manufactured by the same operator. Pulsed-field gel electrophoresis typing of all of the L. monocytogenes isolates obtained from the survey identified 12 different pulsotypes. Different pulsotypes were often identified in samples from the same operator sampled on separate occasions. A total of 46 lots (15.5%) contained Listeria spp. (including L. monocytogenes). The detection of Listeria in samples may highlight the existence of problems in operator processing and/or packaging processes and suggests that improvements in good hygienic practice and implementation of more effective risk mitigation strategies are needed.

Variation in the microbiological quality of commercially produced vacuum-packed cooked sliced meat between production and the end of shelf-life

A study of the microbiological quality of cooked, sliced vacuum-packed meat was undertaken. Three hundred and eighty-one samples were taken (127 sets of three samples) from 55 commercial premises that produced packets of sliced, cooked, vacuum-packed meat for retail sale. The set of three samples consisted of one from the unsliced, cooked meat, one from the sliced product immediately after slicing, and one sliced packet for end of shelf-life testing. Samples were examined for aerobic colony count (ACC), Enterobacteriaceae, Escherichia coli, Listeria, and Salmonella. When compared to current UK guidelines for the quality of ready to eat food, samples were found to be unsatisfactory for ACC, Enterobacteriaceae, and E. coli. Unsatisfactory rates increased at the end of shelf-life compared to the unsliced meat sample results. No samples were positive for Listeria monocytogenes or Salmonella. This data is important for producers setting the shelf-life of their products.

Microbiological quality of wheat grain and flour from two mills in Queensland, Australia

A baseline investigation of the microbiological quality of wheat grain and flour from two mills in Queensland, Australia, was undertaken in order to assess the capacity of these two mills to meet microbiological criteria specified by a customer for raw, non-heat-treated flour. This baseline testing was performed over the 2006 to 2007 wheat season. Three hundred fifty flour samples were monitored for yeast, mold, and Bacillus cereus, 300 for Escherichia coli, 150 for Salmonella, and 100 for aerobic plate count. Fifty grain samples were analyzed for yeast, mold, E. coli, Salmonella, and B. cereus. There was a single isolation of Salmonella Give in unscreened wheat. The yeast, mold, E. coli, and B. cereus prevalences were 56, 40, 2.0, and 4.0% for grain and 71, 17, 0.7, and <0.3% for flour, respectively. Of the positive samples, the means were 3.7, 2.7, 0.6, and 2.1 for grain, and 3.0, 2.8, and 0.8 log CFU/g for flour. The mean of the aerobic plate count was 4.2 log CFU/g with a 95th percentile count of 4.6 log CFU/g. A microbiological quality baseline of wheat grain and flour from these two Queensland mills has been determined. These data in a specific sense assist the two mills to assess their capacity to meet microbiological criteria, and in a general sense provide at least a limited snapshot of Queensland wheat and flour quality for risk assessments being carried out to evaluate the safety of plant and plant products.

Survival of Escherichia coli after isoelectric solubilization and precipitation of fish protein

Protein recovery for fish processing by-products utilizes extreme pH shifts for isoelectric solubilization and precipitation. The purpose of this study was to determine if Escherichia coli would survive exposure to the extreme pH shifts during the protein recovery process. Fresh rainbow trout were beheaded, gutted, and minced and then inoculated with approximately 10(9) CFU of E. coli ATCC 25922 per g, homogenized, and brought to the target pH of 2.0, 3.0, 11.5, or 12.5 by the addition of concentrated hydrochloric acid or sodium hydroxide to solubilize muscle proteins. The homogenate was blended and centrifuged to separate the lipid and insoluble components (bones, skin, insoluble protein, etc.) from the protein solution. The protein solution was subjected to a second pH shift (pH 5.5) resulting in protein precipitation that was recovered with centrifugation. Microbial analysis was conducted on each fraction (i.e., lipid, insoluble components, protein, and water) with selective and nonselective media. The sums of the surviving E. coli in these fractions were compared with the initial inoculum. The greatest total microbial reduction occurred when the pH was shifted to 12.5 (P < 0.05), i.e., a 4.4-log reduction of cells on nonselective media and a 6.0-log reduction of cells on selective media. The use of selective and nonselective media showed that there was significant (P < 0.05) injury sustained by cells exposed to alkaline treatment (pH 11.5 and 12.5) in all fractions except the insoluble fraction at pH 11.5. Increasing the exposure time or the pH may result in greater bacterial reductions in the recovered protein.

Microbiological quality of ready-to-eat food served in schools in Wales, United Kingdom

A survey of the general microbiological quality of ready-to-eat food served in schools was undertaken across Wales, United Kingdom. Of the 2,351 samples taken, four were identified as containing unsatisfactory counts of Escherichia coli, four contained unsatisfactory counts of Staphylococcus aureus, and one contained an unacceptable count of Bacillus cereus when compared with guidelines for the microbiological quality of ready-to-eat food published by the United Kingdom Public Health Laboratory Service in 2000. No samples contained detectable levels of Salmonella, Listeria species, or Clostridium perfringens. When compared with data on the general microbiological quality of food available in Wales, the food sampled from schools was of relatively better microbiological quality.

Prevalence of Listeria monocytogenes and Salmonella in ready-to-eat food in Catalonia, Spain

Listeria monocytogenes and Salmonella are pathogenic bacteria that can contaminate food products during or after processing. Ready-to-eat (RTE) food does not undergo any treatment to ensure its safety before consumption, and therefore risk of foodborne disease must be considered if these pathogens are present in the food. To evaluate the prevalence of these pathogens in RTE food, 140 RTE fish product samples, 501 RTE meat product samples, 462 RTE dairy samples, and 123 RTE dishes and desserts, providing a total of 1,226 samples, were collected from retail stores and food industry and analyzed for the presence of L. monocytogenes. A total of 1,379 samples consisting of 187 RTE fish products and 569 RTE meat products, 484 RTE dairy products, and 139 RTE dishes and desserts were collected and analyzed for the presence of Salmonella. L. monocytogenes was isolated from 20% of frozen Atlantic bonito small pies, 7.9% of smoked salmon samples, 11.1% of the pork luncheon meat samples, 6.2% of frozen chicken croquettes, 16.9% of cured dried sausage samples, 12.5% of cooked ham samples, and 20% of cooked turkey breast samples. L. monocytogenes was also found to be present in 1.3% of fresh salty cheese samples and 15.1% of frozen cannelloni samples. Salmonella was isolated from 1.2% of smoked salmon samples, 1.5% of frozen chicken croquettes, 2% of cooked ham samples, and 11.1% of cured dried sausage samples. Overall, occurrence of these pathogens in RTE foods was similar to that previously reported in the literature.