In this study, the persistence of toxigenic Escherichia coli (E. coli ) on dried chamomile, peppermint, ginger, cinnamon, black and green teas stored under 4, 10, and 25°C was determined. The E. coli survival rate in ginger and cinnamon teas decreased below 0 on Day 5. In the other tested teas, E. coli survivability showed a downward trend over time, but never dropped to 0. Chamomile tea retained the greatest population of viable E. coli . Meanwhile, die‐off of E. coli was higher at 25°C compared to lower temperatures. Additionally, fate of E. coli during brewing at 60, 70 and 80°C was evaluated. The E. coli population was reduced to below 2 Log colony forming units (CFU)/g after 1 min at 80°C, At the same time, the E. coli survival at 60°C was higher than that at 70°C in all tested teas. The data indicated that if E. coli survives after storage of prepared teas, it may also survive and grow after the brewing process, especially if performed using temperatures <80°C. Finally, we analyzed the correlations between temperature, time, tea varieties and E. coli survival, and successfully constructed a random forest regression model. The results of this study can be used to predict changes in E. coli during storage and fate during the brewing process. Results will form the basis of undertaking a risk assessment.
Category Archives: Research
Research – Study suggests green tea extracts could reduce risk of infection with diarrhoea-causing Norovirus
Scientists also found that green tea extract in combination with chitosan films can reduce levels of bacteria such as E coli and L innocua to undetectable levels after 24 hours of exposure
It’s not uncommon for one to get an upset stomach occasionally, particularly after eating outside food. This is often the result of different kinds of bacteria and viruses present in the food items. In a research, published in the International Journal of Food Science on 4 July 2020, scientists found that green tea extracts can help in reducing the risk of getting infected with a diarrhoea-causing virus known as norovirus.
Research – Evasion of Plant Innate Defense Response by Salmonella on Lettuce
To establish host association, the innate immune system, which is one of the first lines of defense against infectious disease, must be circumvented. Plants encounter enteric foodborne bacterial pathogens under both pre- and post-harvest conditions. Human enteric foodborne pathogens can use plants as temporary hosts. This unique interaction may result in recalls and illness outbreaks associated with raw agricultural commodities. The purpose of this study was to determine if Salmonella enterica Typhimurium applied to lettuce leaves can suppress the innate stomatal defense in lettuce and utilization of UD1022 as a biocontrol against this ingression. Lettuce leaves were spot inoculated with S. Typhimurium wild type and its mutants. Bacterial culture and confocal microscopy analysis of stomatal apertures were used to support findings of differences in S. Typhimurium mutants compared to wild type. The persistence and internalization of these strains on lettuce was compared over a 7-day trial. S. Typhimurium may bypass the innate stomatal closure defense response in lettuce. Interestingly, a few key T3SS components in S. Typhimurium were involved in overriding stomatal defense response in lettuce for ingression. We also show that the T3SS in S. Typhimurium plays a critical role in persistence of S. Typhimurium in planta. Salmonella populations were significantly reduced in all UD1022 groups by day 7 with the exception of fliB and invA mutants. Salmonella internalization was not detected in plants after UD1022 treatment and had significantly higher stomatal closure rates (aperture width = 2.34 μm) by day 1 compared to controls (8.5 μm). S. Typhimurium SPI1 and SPI2 mutants showed inability to reopen stomates in lettuce suggesting the involvement of key T3SS components in suppression of innate response in plants. These findings impact issues of contamination related to plant performance and innate defense responses for plants.
Research -New study shows link between animal operation and orchard contamination
One in every five air samples in almond orchards adjacent to a poultry operation tested positive for E. coli during a two-year study published recently.
“Microorganisms Move a Short Distance into an Almond Orchard from an Adjacent Upwind Poultry Operation” comes as romaine growers continue to study the impact of a 100,000-head cattle feed lot adjacent to Arizona growing fields.
Lettuce growers from regions in California are also looking at implications of having animal operations in the areas near food crops. The Food and Drug Administration recently posted a conclusion that animal operations were the likely cause behind romaine E. coli outbreaks in 2018-19.
The almond research, published in the peer-reviewed journal Applied and Environmental Microbiology,
Research -Evaluation of Public Health Risk for Escherichia coli O157:H7 in Cilantro
This study sought to model the growth and die-off of Escherichia coli (E. coli) O157:H7 along the cilantro supply chain from farm-to-fork to investigate its risk to public health. Contributing factors included in the model were on farm contamination from irrigation water and soil, solar radiation, harvesting, and transportation and storage times and temperatures. The developed risk model estimated the microbiological risks associated with E. coli O157:H7 in cilantro and determined parameters with the most effect on the final concentration per serving for future mitigation strategies. Results showed a similar decrease in the E. coli O157:H7 (median values) concentrations along the supply chain for cilantro grown in both winter and summer weather conditions. With an estimated 0.1% prevalence of E. coli O157:H7 contamination for cilantro post-harvest used for illustration, the model predicted the probability of illness from consuming fresh cilantro as very low with fewer than two illnesses per every one billion servings of cilantro (1.6 x 10-9; 95th percentile). Although rare, 3.7% and 1.6% of scenarios run in this model for summer and winter grown cilantro, respectively, result in over 10 cases per year in the United States. This is reflected in real life where illnesses from cilantro are seen rarely but outbreaks have occurred. Sensitivity analysis and scenario testing demonstrated that ensuring clean and high quality irrigation water and preventing temperature abuse during transportation from farm to retail, are key to reducing overall risk of illness.
Posted in Contaminated water, E.coli, E.coli O157, E.coli O157:H7, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, microbial contamination, Microbiology, Research, STEC, STEC E.coli, Uncategorized, Water, water microbiology, Water Safety
UK -Cardiff City Road restaurant found infested with salmonella-carrying cockroaches
A popular City Road café in the Welsh capital was closed down after around 100 cockroaches were discovered in the kitchen and dining area.
The insects were found at Mr Tikka on City Road in Roath, Cardiff, when council officers carried out an unannounced routine inspection on May 7 of last year.
When officers arrived, the owner, Rubi Begum, was seen sweeping two live insects off the counter and white powder – believed to be an insecticide – was on the kitchen floor.
More insects, including German cockroaches, which pose a significant health risk, were later discovered in the kitchen and dining area where customers were eating.
Posted in bacterial contamination, cross contamination, food contamination, Food Hygiene, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Pathogen, Food Safety, Food Spoilage, Food Testing, microbial contamination, Research, Salmonella, Uncategorized
Research – Raw is risky: Why salads are the biggest source of food poisoning and what to do to avoid it
Brian Adam of Intallght writes just over a year ago, the United States saw the largest outbreak of E. coli since 2006; affecting at least 98 people in more than 20 states. The origin wa bagged romaine lettuce. Unfortunately, this is not an isolated case. Vegetables and fresh fruit have become a real headache for food safety experts.
Today in the United States, fresh vegetables are the largest source of food poisoning. In Europe, the figures are not so pristine, but the bacteria and viruses associated with this type of food also are to blame for the vast majority of poisonings. We are facing a real danger for food safety: salads.
Research – Growth and survival of foodborne pathogens during soaking and drying of almond (Prunus dulcis) kernels
The practice of soaking almonds prior to consumption is popular both commercially and at home. The food safety implications of soaking almonds was investigated through analysis of blogs and videos (n = 85 recipes) to identify both the reasons for soaking almonds and the common practices employed. Among the recipes analyzed, the most common reasons for soaking almonds (94.1%) were perceived benefits such as improved digestion and nutrient uptake. Most recipes (34.1%) suggested soaking at “room temperature” for times that ranged from 4 to 24 h or, more commonly, “overnight” (51.8%). Post-soaking drying instructions were provided in 40 recipes (47.1%). Among those providing a drying temperature (31.8%), 85% specified 66°C and lower. To evaluate the growth of foodborne pathogens during almond soaking, separate cocktails of Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella enterica were inoculated onto raw almonds or into the soak water (almonds-to-water ratios of 1:1 and 1:3 [w/v]). Populations were monitored during soaking at 15, 18, and 23°C for up to 24 h, and during post-soak drying at 66°C for 14 h (for Salmonella only). At 15°C and a 1:1 almond:water ratio, no significant population increase (P > 0.05) was observed between 0 and 24 h for any of the pathogens. At 18°C, increases of 0.63, 1.70, and 0.88 log CFU/sample were observed over 24 h for populations of E. coli O157:H7, L. monocytogenes, and Salmonella, respectively. Populations of E. coli O157:H7, L. monocytogenes, and Salmonella increased by 3.48, 3.22, and 3.94 log CFU/sample, respectively, after 24 h at 23°C. When soaked almonds were dried for 14 h at 66°C, moisture and water activity decreased from 40% to ~6% and 0.99 to 0.60, respectively, but no significant reduction in Salmonella populations was observed. Recommendations for using shorter times (<8 h) and cooler temperatures (≤15°C) should reduce the potential for foodborne pathogens, if present, to grow during soaking of almonds.
Research – Sporeforming Bacteria Associated with Dairy Powders Can be Found in Bacteriological Grade Agar-Agar Supply
Thermophilic sporeforming bacteria are found ubiquitously in natural environments and therefore are present in a number of agricultural food products. Spores produced by these bacteria can survive harsh environmental conditions encountered during food processing and have been implicated in food spoilage. During research efforts to develop a standardized method for enumerating spores in dairy powders, the dairy powder associated thermophilic sporeformer Anoxybacillus flavithermus was discovered growing in un-inoculated control plates of Tryptic Soy agar (TSA) supplemented with 1% w/v starch, after incubation at thermophilic (55°C) growth temperatures. This paper reports the investigation into the source of this thermophilic sporeformer in TSA medium components and characterization of the bacterial isolates collected. Aqueous solutions of Tryptic Soy broth (TSB) powder from four suppliers and four agar-agar powders (two manufacturing lots from one supplier; Agar A_1 and Agar A_2, and two from separate suppliers; Agar B and Agar C) were subjected to two different autoclave cycle times (121°C for 15 min or 121°C for 30 min) and then prepared as TSA. After incubation at 55°C for 48h, bacterial growth was only observed in media prepared from both lots of Agar A agar-agar powder, and only when they were subjected to a 15 min autoclave cycle, implicating these powders as a source of the sporeformer contamination. Genetic characterization of 49 isolates obtained indicated the presence of five unique rpoB allelic types (ATs) of the thermophilic sporeformer, Geobacillus spp . in agar-agar powder from Agar A. These results not only highlight the importance of microbiological controls, but also alert researchers to the potential for survival of thermophilic sporeformers such as Anoxybacillus and Geobacillus in microbiological media used for detection and enumeration of these same thermophilic sporeformers in products like dairy powders.
Spain – Spain plans to tighten rules for marketing of unpasteurised milk
Spanish scientists have proposed additional requirements for the marketing of raw milk but have not gone as far as to ban it.
European regulation allows unpasteurized milk for direct human consumption to be placed on the market without treatment to kill bacteria, parasites and viruses. The current situation in Spain follows this legislation with no additional requirements so raw milk can be sold regardless of volume.
The Spanish Agency for Food Safety and Nutrition (AESAN) asked its Scientific Committee to assess whether risk management measures related to raw milk intended for direct human consumption are adequate to provide a high level of consumer protection. Or if it was necessary to prohibit raw milk sold in this way in Spain.
Proposed measures include microbiological criteria, mandatory packaging of milk and indicating on the label: “Raw milk without thermal treatment: boil before consumption” and “Maintain refrigerated at temperatures between 1 and 4 degrees C (34 to 39 degrees F).
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