Category Archives: Food Microbiology Research

Research – Microbial contamination of grocery shopping trolleys and baskets in west Texas, 2020

Barf Blog

Indicator microorganisms evaluated were those detected by aerobic plate count (APC), yeast and molds (YM), Enterobacteriaceae (EB). Environmental listeria (EL), coliforms (CF), and E. coli (EC).  In addition, listeria monocytogenes, staphylococcus aureus, Escherichia coli O157 and salmonella sp. Were tested for.  Trolley grills (n=36) had 2.7 x 10CFU/cm2.  Trolley handles (n=36) had 2.7 x 10of CF and 5.2 CFU/cm2 of YM.  The bottom of handheld baskets (n=25) had 3.5 x 105 CFU/cm2 of CF and 5.07 CFU/cmof EC.  S. aureus was found on 96% of the baskets, 50% of the trolley handles (18 out of 36 samples), and 42% of the trolleys’ grills.  E. coli O157 was identified on 17% of baskets, 3% on trolley grills, and 3% on handles.  Salmonella sp. was detected on 16% of baskets and 8% of trolley grills.  L. monocytogenes was detected on 17% of the bottoms of handheld baskets but on none of the other samples. 

Research -Evaluation of the Efficacy of Three Direct Fed Microbial Cocktails To Reduce Fecal Shedding of Escherichia coli O157:H7 in Naturally Colonized Cattle and Fecal Shedding and Peripheral Lymph Node Carriage of Salmonella in Experimentally Infected Cattle

Journal of Food Protection

ABSTRACT

Two experiments were conducted to evaluate the feeding of direct fed microbials (DFMs) on fecal shedding of Escherichia coli O157:H7 in naturally infected cattle (experiment I) and on Salmonella in the feces and peripheral lymph nodes (PLNs) of experimentally infected cattle (experiment II). Thirty cattle, 10 per treatment, were used in each experiment. Treatments in experiment I consisted of a control (lactose carrier only); DFM1, a 1:1 ratio of Enterococcus faecium and Lactobacillus animalis; and DFM2, a 1:1 ratio of Lactobacillus acidophilus and Pediococcus acidilactici. In Experiment II, DFM1 was replaced with DFM3, a 1:2 ratio of Lactobacillus reuteri and other Lactobacillus strains. Additives were mixed in water and applied as a top-dressing to each pen’s daily ration for 50 days. Approximately half-way through each experiment, the DFM concentration was doubled for the remainder of the study. Fecal samples were collected throughout experiment I and cultured for E. coli O157:H7. Cattle in experiment II were inoculated intradermally with Salmonella Montevideo on days 32, 37, and 42 and then necropsied on days 49 and 50 (five cattle per treatment on each day). Innate immune function was assessed on days 29, 49, and 50. In experiment I, fecal concentration and prevalence of E. coli O157:H7 were not different (P > 0.10) nor was there an effect (P = 0.95) on the percentage of super shedders (cattle shedding ≥3.0 log CFU/g of feces). In experiment II, no treatment differences (P > 0.05) were observed for Salmonella in the PLNs except for the inguinal nodes, which had a significantly lower Salmonella prevalence in DFM-supplemented cattle than in the controls. Immune function, as measured by monocyte nitric oxide production and neutrophil oxidative burst, was decreased (P < 0.05) in the DFM treatment groups. Although results of this research indicate little to no effect of these DFMs on E. coli O157:H7 or Salmonella in cattle, an increase in the duration of administration to that similar to what is used for commercial cattle might elicit treatment differences.

HIGHLIGHTS
  • Direct fed microbials were evaluated for pathogen mitigation in cattle.

  • No treatment effects on fecal shedding of E. coli O157:H7 were observed.

  • DFM treatment reduced Salmonella in only one the four lymph node types examined.

  • Under these experimental conditions, short-term feeding of DFMs failed to mitigate pathogens.

 

Information -Food Poisoning

foodsafety.gov

Food poisoning—any illness or disease that results from eating contaminated food—affects millions of Americans each year. While the American food supply is among the safest in the world, the Federal government estimates that there are about 48 million cases of foodborne illness annually—the equivalent of sickening 1 in 6 Americans each year. And each year these illnesses result in an estimated 128,000 hospitalizations and 3,000 deaths.

Causes of Food Poisoning

  • Bacteria and Viruses: Bacteria and viruses are the most common cause of food poisoning. The symptoms and severity of food poisoning vary, depending on which bacteria or virus has contaminated the food.
  • Parasites: Parasites are organisms that derive nourishment and protection from other living organisms known as hosts. In the United States, the most common foodborne parasites are protozoa, roundworms, and tapeworms.
  • Molds, Toxins, and Contaminants: Most food poisoning is caused by bacteria, viruses, and parasites rather than toxic substances in the food. But some cases of food poisoning can be linked to either natural toxins or added chemical toxins.
  • Allergens: Food allergy is an abnormal response to a food triggered by your body’s immune system. Some foods, such as nuts, milk, eggs, fish, crustacean shellfish, tree nuts, peanuts, wheat or soybeans, can cause allergic reactions in people with food allergies.

Click the link above for more information.

Research – Effect of Eryngium caeruleum essential oil on microbial and sensory quality of minced fish and fate of Listeria monocytogenes during the storage at 4°C

Wiley Online

The present study investigated in vitro antimicrobial activity of Eryngium caeruleum essential oil (EEO) against five foodborne pathogenic bacteria based on microdilution and disk diffusion methods. Moreover, its effects on specific spoilage microorganisms, inoculated Listeria monocytogenes, and its sensory changes in minced fish were evaluated during 12 days of storage at refrigeration temperature. The results showed that Staphylococcus aureus and Escherichia coli were the most sensitive and the most resistant bacteria with a minimum inhibitory concentration of 0.125 and 1 mg/ml, as well as inhibition zones of 15.66 and 11.66 mm, respectively. Regarding the antimicrobial effect of EEO on the microbial profile and inoculated L. monocytogenes, treating with 0.4% EEO caused a significant decrease in the studied microorganisms when compared to the control group (p < 0.05). In addition, considering the sensory evaluation, the best scores were observed for the samples treated with 0.2% and 0.4% EEO. However, none of the groups obtained acceptable scores until the final day of storage except for the color attribute. In general, sensory evaluation and its correlation with microbial counting indicated that the treatment with 0.4% EEO was able to preserve the microbial quality of the minced fish at refrigeration temperature without any undesirable sensory effects.

Research – Thermal and Chemical Treatments To Reduce Salmonella on Alfalfa (Medicago sativa) and Broccoli (Brassica oleracea var. italica) Seeds before and during the Sprouting Process: A Hurdle Approach

Journal of Food Protection

ABSTRACT

Sprouts are vehicles of foodborne diseases caused by pathogens such as Salmonella. The aim of this study was to evaluate thermal and chemical treatments applied as a hurdle approach to reduce Salmonella in alfalfa (Medicago sativa) and broccoli (Brassica oleracea var. italica) seeds before and during their germination. Seeds, inoculated and then dried at 55°C for 48 h, were subjected to a chemical treatment and a thermal shock with (i) 75 mM caprylic acid at 70°C for 5 s, (ii) 0.04% CaO at 70°C for 5 s, or (iii) 1% H2O2 at 70°C for 5 s. After each treatment, seeds were immersed in water at 3°C for 5 s. Next, the imbibition process was carried out with 0.016% H2O2 at pH 3.0. Finally, the seeds were transferred to a rotary drum-type germinator and were sprayed with the same chemical solution that was applied before the imbibition process, for 20 s at intervals of 5 min for 40 min at 3 rpm. All chemical treatments reduced Salmonella at least 5 log CFU/g on both seeds. Germination rates between 90 and 93% were obtained after application of thermal and chemical treatments. Salmonella was not detected after the imbibition stage when caprylic acid and H2O2 treatments were applied. However, during the germination process of both seeds, Salmonella counts of >6 log CFU/g were obtained despite all treatments being applied at different stages of the sprouting process. These results demonstrated that thermal and chemical treatments used as a hurdle approach to control Salmonella on alfalfa and broccoli seeds significantly reduced the pathogen concentration on seeds >5 log but were ineffective to eliminate Salmonella and to control its growth during the sprouting process. The production of safe sprouts continues to be a major challenge for industry.

HIGHLIGHTS
  • A hurdle approach reduces Salmonella concentration >5 log on alfalfa and broccoli seeds.

  • Germination rates over 90% were reached on alfalfa and broccoli seeds after sequential treatments.

  • Salmonella counts increase during germination, despite the efficacy of previous treatments on seeds.

  • Production of safe sprouts continues to be a major challenge for industry.

Research – Foodborne Illness and the Struggle for Food Safety

CDC

Professor Timothy D. Lytton, a keen scholar of regulatory evolution, provides a lively and well-documented guide to 150 years of major advances in food safety regulation and prevention in the United States. He starts with the early efforts to cleanse and regulate the milk supply in the 19th century that ultimately led to near-universal pasteurization. Efforts to make canned food free of botulism in the 1920s led to a new focus on critical control steps in processing, using sufficient time and heat to eliminate the risk, and thus to a new general approach based on process control. Modernizing meat inspection with process control logic in the 1990s and the recent efforts to make fresh produce safer in the 2000s take the reader to the controversies of the present day.

This book fills a critical gap, weaving the history of public health, regulatory agencies, and the food industry together with issues of immediate concern today. It is an innovative perspective that captures the complexity of the system beyond the scientific report or published regulation. The book should be of interest to students and practitioners of public health and food science and anyone interested in making food reliably safe.

With fresh examples and detailed interviews, Lytton illustrates the dynamic interplay of outbreak investigations, better prevention strategies developed by industry, consumer advocacy, and regulations. He explains why the resulting balance is a punctuated equilibrium, with longer steady states ending in momentous rapid change. Large and catastrophic outbreaks come as the final trigger, as “focusing events” that, with media coverage, increase public attention and create pressure for change. Lytton tells the striking and less well-known story of what happens behind the scenes as food safety champions within the industry push new solutions and voluntary standards forward, show how they could reduce contamination, and gain adherents up and down the food supply chain, thus leading the way for others in industry and regulators to follow. He also deftly outlines the complex roles of third-party auditors, who provide information to one company about the safety practices of its suppliers, and provides a fresh perspective on the growing role that liability insurers may play in the future.

This is history that uplifts, showing how we honor those who suffered from and died of a foodborne disease that is now preventable in the form of better practices and safer food today. In the crucible of public action, it reminds us all how these advances begin and, with feedback and learning, how they can succeed.

Information – Food Safety Charts – Cold Food Storage Chart

Food Safety.gov 

Follow the guidelines at the link above for storing food in the refrigerator and freezer. The short time limits for home-refrigerated foods will help keep them from spoiling or becoming dangerous to eat. The guidelines for freezer storage are for quality only—frozen foods stored continuously at 0 °F or below can be kept indefinitely.

Information – Food Safety – People At Risk

Food Safety.gov

Food poisoning or foodborne illness can affect anyone who eats food contaminated by bacteria, viruses, parasites, toxins, or other substances, but certain people are more likely to get sick or to have a serious illness.

Know whether you’re in a group of people who are more likely to get food poisoning, and make safer choices to reduce your risk for foodborne illness.

People at risk include:

If you or someone you care for are included in one of these groups, follow our four basic steps to food safety and the additional tips included below.

Clean: Wash hands and surfaces often.

Separate: Separate raw meat and poultry from ready-to-eat food.

Cook: Cook food to the right temperature.

Chill: Chill raw meat and poultry, as well as cooked leftovers, promptly (within 2 hours).

Click on the link above for more information.

Information – Food Safety Charts – Food Safety During Power Outage

Food Safety.gov

Refrigerated Food and Power Outages: When to Save It and When to Throw It Out

As the USDA notes in Keeping Food Safe During an Emergency, your refrigerator will keep food safe for up to 4 hours during a power outage. Keep the door closed as much as possible. Discard refrigerated perishable food such as meat, poultry, fish, eggs, and leftovers after 4 hours without power.

After a power outage never taste food to determine its safety. You will have to evaluate each item separately—use this chart  in the link above as a guide.

When in Doubt, Throw it Out!

Research – Prevalence of Salmonella in cucumbers, antibiotic and acid resistances and description of the kinetic behavior with dynamic model during storage

Wiley Online

This study isolated Salmonella from cucumbers, analyzed the antibiotic resistance and acid resistance for the isolates and developed a dynamic model. Salmonella prevalence in cucumbers and their resistances were determined. To describe the kinetic behavior of Salmonella isolates, the isolates were inoculated into cucumbers, and Salmonella cell counts were enumerated during storage at 10–30°C. The Baranyi model was fitted to the cell count data to calculate kinetic parameters (lag phase duration [LPD] and maximum specific growth rate (μmax)], and a polynomial model was fitted to the kinetic parameters as a function of temperature. The model performance was evaluated with root mean square error (RMSE). Using these models, a dynamic model was developed. Salmonella were detected in 3 of 24 cucumbers, all of which were multidrug‐resistant and one was acid‐resistant. As storage temperature increased, LPD decreased and μmax increased. These models were appropriate with 0.367 of RMSE. These results suggest that cross‐contaminated Salmonella could increase during transportation, and it may lead to human infection.