Category Archives: Microbiology Investigations

Information – Cleaning Your Refrigerator Because of a Food Recall

Posted on September 14, 2021 by | Leave a comment

CDC

If you have a recalled food item in your refrigerator, it’s important to throw out the food and clean your refrigerator. Germs in the recalled food could spread to drawers or shelves in your refrigerator.

How to Clean Your Refrigerator After a Food Recall

Items needed to clean your refrigerator:

items needed to clean refrigerator

  • Sealed bags
  • Hot, soapy water
  • Clean towels
  • Optional: water + bleach
Standing next to refrigerator

Download refrigerator cleaning infographic pdf icon[PDF – 1 page]

Step 1 – Throw out recalled food

  • Throw out the recalled food, and any other foods stored with it or touching it.
  • Put it in a sealed bag in the garbage.
  • If the recalled food was stored in a reusable container, wash it with hot, soapy water before reusing.
Step 1 to cleaning your fridge throw out recalled food

Step 2 – Empty your refrigerator

  • Empty the rest of the items in your refrigerator and put them on a counter or table while you clean.
  • Take out shelving, drawers, and any other removable parts.
  • Don’t leave unrefrigerated food out for more than 2 hours.

Step 3 – Wash removable parts

  • Wash shelving, drawers, and any other removable parts by hand with hot, soapy water.
  • Dry with a clean towel.
  • Don’t run cold glass shelves or drawers under hot water because the glass could crack. Let them come to room temperature first.

Step 4 – Clean and sanitize inside the refrigerator

  • Wipe the inside of the empty refrigerator with hot, soapy water; then wipe with clean water to rinse off soap.
  • Dry with a clean towel.
  • Don’t forget to wipe inside the doors and any drawers that cannot be removed.
Step 2 of cleaning fridge wash shelving and removable parts with soap and water

* Optional step

Use a solution of 1 tablespoon of liquid bleach in 1 gallon of water to sanitize your refrigerator. Do this after cleaning the refrigerator with hot, soapy water.

Picture of bleach and bucket

Step 5 – Return shelves, drawers, and food

  • Put the shelves, drawers, and other removable parts back in the refrigerator, along with the other items you took out.
  • Wipe food containers and drink containers with hot, soapy water before returning to the clean refrigerator.

And don’t forget!

  • Wash your hands with water and soap once you’ve finished cleaning.
  • Use hot, soapy water to wipe kitchen counters that held food, drinks, refrigerator parts, and any cleaning materials.
  • Wash any towels you used to dry the refrigerator before using them again.

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Posted in Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Safety, microbial contamination, Microbiological Risk Assessment, Microbiology, Microbiology Investigations

Research – The influence of organic load and free chlorine on Salmonella cross-contamination of tomatoes in a model flume system

Posted on September 13, 2021 by | Leave a comment

Journal of Food Protection

The process of washing tomatoes in dump (flume) tanks has been identified as a potential source of cross-contamination. This study’s objective was to assess the potential for Salmonella enterica cross-contamination at various inoculation levels at the presence of 0 and 25 mg/L free chlorine (HOCl) and organic matter.  Uninoculated tomatoes were introduced into a laboratory-based model flume containing tomatoes inoculated with a cocktail of five rifampicin-resistant Salmonella enterica serovars at 104, 106, or 108 CFU/tomato in water containing 0 or 25 mg/L HOCl and 0 or 300 mg/L chemical oxygen demand (COD). Uninoculated tomatoes were removed from the water at after 5, 30, 60, 120 s and were placed in bags containing tryptic soy broth supplemented with rifampicin and 0.1% sodium thiosulfate. Following incubation, enrichments were plated on tryptic soy agar supplemented with rifampicin and xylose lysine deoxycholate agar to determine the presence of Salmonella. HOCl and pH were measured before and after each trial. The HOCl in water containing 300 mg/L COD significantly (P≤0.05) declined by the end of each 120 s trial, most likely due to the increased demand for the oxidant. Higher inoculum levels and lower HOCl concentrations were (P≤0.05) significant factors that contributed to increased cross-contamination seen in this study. When HOCl levels were at 25 mg/L, no Salmonella was recovered on non-inoculated tomatoes under all conditions when inoculum levels were at 104 CFU/tomato. When the inoculum was increased to 106 and 108 CFU/tomato, cross-contamination was observed, independent of COD levels. The results from this study show that the currently required sanitizer level (e.g., 100 or 150 mg/L) for flume water may be higher than necessary and warrants re-evaluation.

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Posted in Food Micro Blog, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Technology, microbial contamination, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Research, Salmonella, Technology

Information – Lettuce, Other Leafy Greens, and Food Safety

Posted on September 13, 2021 by | Leave a comment

CDC

Eurofins Food Testing UK

Vegetables are an important part of a healthy, balanced diet. Leafy vegetables (called leafy greens on this page) such as lettuce, spinach, cabbage, kale, and bok choy, provide nutrients that help protect you from heart disease, stroke, and some cancers.

But leafy greens, like other vegetables and fruits, are sometimes contaminated with harmful germs. Washing does not remove all germs because they can stick to the surfaces of leaves and even get inside them. If you eat contaminated raw (uncooked) leafy greens, such as in a salad, you might get sick. To prevent contamination, leafy greens should be grown and handled safely at all steps in the journey from farm to fork.

  • CDC estimates that germs on produce that is eaten raw cause a large percentage of U.S. foodborne illnesses (also called food poisoning).
  • Leafy greens and other vegetable row crops are a major source of E. coli O157 infections.
  • Other harmful germs found on leafy greens include norovirus, Salmonella, Listeria, and Cyclospora.

Although anyone can get food poisoning, these groups are more likely to get sick and to have a more serious illness:

  • Adults aged 65 and older
  • Children younger than 5 years
  • People who have health problems or take medicines that lower the body’s ability to fight germs and sickness (a weakened immune system)
  • Pregnant women

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Posted in Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Safety, microbial contamination, Microbiological Risk Assessment, Microbiology, Microbiology Investigations

Information – Cold Food Storage Chart

Posted on September 12, 2021 by | Leave a comment

Follow the guidelines below 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.

Looking for a specific item? Check out FoodKeeper to find storage tips for over 650 food and beverages.

PDF Table

Food Type Refrigerator
(40 °F or below)		 Freezer
(0 °F or below)
Salad Egg, chicken, ham, tuna, and macaroni salads 3 to 4 days Does not freeze well
Hot dogs Opened package 1 week 1 to 2 months
Unopened package 2 weeks 1 to 2 months
Luncheon meat Opened package or deli sliced 3 to 5 days 1 to 2 months
Unopened package 2 weeks 1 to 2 months
Bacon and sausage Bacon 1 week 1 month
Sausage, raw, from chicken, turkey, pork, or beef 1 to 2 days 1 to 2 months
Sausage, fully cooked, from chicken, turkey, pork, or beef 1 week 1 to 2 months
Sausage, purchased frozen After cooking, 3-4 days 1-2 months from date of purchase
Hamburger, ground meats and ground poultry Hamburger, ground beef, turkey, chicken, other poultry, veal, pork, lamb, and mixtures of them 1 to 2 days 3 to 4 months
Fresh beef, veal, lamb, and pork Steaks 3 to 5 days 4 to 12 months
Chops 3 to 5 days 4 to 12 months
Roasts 3 to 5 days 4 to 12 months
Ham Fresh, uncured, uncooked 3 to 5 days 6 months
Fresh, uncured, cooked 3 to 4 days 3 to 4 months
Cured, cook-before-eating, uncooked 5 to 7 days or “use by” date 3 to 4 months
Fully-cooked, vacuum-sealed at plant, unopened 2 weeks or “use by” date 1 to 2 months
Cooked, store-wrapped, whole 1 week 1 to 2 months
Cooked, store-wrapped, slices, half, or spiral cut 3 to 5 days 1 to 2 months
Country ham, cooked 1 week 1 month
Canned, labeled “Keep Refrigerated,” unopened 6 to 9 months Do not freeze
Canned, shelf-stable, opened

Note: An unopened, shelf-stable, canned ham can be stored at room temperature for 2 years.

 3 to 4 days 1 to 2 months
Prosciutto, Parma or Serrano ham, dry Italian or Spanish type, cut 2 to 3 months 1 month
Fresh poultry Chicken or turkey, whole 1 to 2 days 1 year
Chicken or turkey, pieces 1 to 2 days 9 months
Eggs Raw eggs in shell 3 to 5 weeks Do not freeze in shell. Beat yolks and whites together, then freeze.
Raw egg whites and yolks

Note: Yolks do not freeze well

 2 to 4 days 12 months
Raw egg accidentally frozen in shell

Note: Toss any frozen eggs with a broken shell

 Use immediately after thawing Keep frozen, then
refrigerate to thaw
Hard-cooked eggs 1 week Do not freeze
Egg substitutes, liquid, unopened 1 week Do not freeze
Egg substitutes, liquid, opened 3 days Do not freeze
Egg substitutes, frozen, unopened After thawing, 1 week or refer to “use by” date 12 months
Egg substitutes, frozen, opened After thawing, 3 to 4 days or refer to “use by” date Do not freeze
Casseroles with eggs After baking, 3 to 4 days After baking, 2 to 3 months
Eggnog, commercial 3 to 5 days 6 months
Eggnog, homemade 2 to 4 days Do not freeze
Pies: Pumpkin or pecan After baking, 3 to 4 days After baking, 1 to 2 months
Pies: Custard and chiffon After baking, 3 to 4 days Do not freeze
Quiche with filling After baking, 3 to 5 days After baking, 2 to 3 months
Soups and stews Vegetable or meat added 3 to 4 days 2 to 3 months
Leftovers Cooked meat or poultry 3 to 4 days 2 to 6 months
Chicken nuggets or patties 3 to 4 days 1 to 3 months
Pizza 3 to 4 days 1 to 2 months

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Posted in Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Testing, Food Safety, microbial contamination, Microbiological Risk Assessment, Microbiology, Microbiology Investigations

Information – Four Steps to Food Safety: Clean, Separate, Cook, Chill

Posted on September 10, 2021 by | Leave a comment

CDC

Following four simple steps at home—Clean, Separate, Cook, and Chill—can help protect you and your loved ones from food poisoning.
Clean your hands

Clean: Wash your hands and surfaces often

  • Germs that cause food poisoning can survive in many places and spread around your kitchen.
  • Wash hands for 20 seconds with soap and water before, during, and after preparing food and before eating.
  • Wash your utensils, cutting boards, and countertops with hot, soapy water.
  • Rinse fresh fruits and vegetables under running water.
separate meats from vegetables don't cross contaminate

Separate: Don’t cross-contaminate

  • Raw meat, poultry, seafood, and eggs can spread germs to ready-to-eat foods—unless you keep them separate.
    • Use separate cutting boards and plates for raw meat, poultry, and seafood.
    • When grocery shopping, keep raw meat, poultry, seafood, and their juices away from other foods.
    • Keep raw meat, poultry, seafood, and eggs separate from all other foods in the fridge.
Cook to the right temperature

Cook: To the right temperature

  • Food is safely cooked when the internal temperature gets high enough to kill germs that can make you sick. The only way to tell if food is safely cooked is to use a food thermometer. You can’t tell if food is safely cooked by checking its color and texture.
  • Use a food thermometer to ensure foods are cooked to a safe internal temperature. Check this chart for a detailed list of foods and temperatures
    • 145°F for whole cuts of beef, pork, veal, and lamb (then allow the meat to rest for 3 minutes before carving or eating)
    • 160°F for ground meats, such as beef and pork
    • 165°F for all poultry, including ground chicken and turkey
    • 165°F for leftovers and casseroles
    • 145°F for fresh ham (raw)
    • 145°F for fin fish or cook until flesh is opaque
Refrigerate food promptly to avoid food poisoning

Chill: Refrigerate promptly

Bacteria can multiply rapidly if left at room temperature or in the “Danger Zone” between 40°F and 140°F. Never leave perishable food out for more than 2 hours (or 1 hour if it’s hotter than 90°F outside).

  • Keep your refrigerator at 40°F or below and know when to throw food out.
  • Refrigerate perishable food within 2 hours. (If outdoor temperature is above 90°F, refrigerate within 1 hour.)
  • Thaw frozen food safely in the refrigerator, in cold water, or in the microwave. Never thaw foods on the counter, because bacteria multiply quickly in the parts of the food that reach room temperature.

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Posted in Food Micro Blog, Food Microbiology Blog, Food Microbiology Testing, Food Safety, microbial contamination, Microbiological Risk Assessment, Microbiology, Microbiology Investigations

Research – Survival of Escherichia coli and Listeria innocua on Lettuce after Irrigation with Contaminated Water in a Temperate Climate

Posted on September 9, 2021 by | Leave a comment

MDPI

Microbial disease outbreaks related to fresh produce consumption, including leafy green vegetables, have increased in recent years. Where contamination occurs, pathogen persistence may represent a risk for consumers’ health. This study analysed the survival of E. coli and L. innocua on lettuce plants watered with contaminated irrigation water via a single irrigation event and within stored irrigation water. Separate lettuce plants (Lactuca sativa var. capitata) were irrigated with water spiked with Log10 7 cfu/mL of each of the two strains and survival assessed via direct enumeration, enrichment and qPCR. In parallel, individual 20 L water microcosms were spiked with Log10 7 cfu/mL of the individual strains and sampled at similar time points. Both strains were observed to survive on lettuce plants up to 28 days after inoculation. Direct quantification by culture methods showed a Log10 4 decrease in the concentration of E. coli 14 days after inoculation, and a Log10 3 decrease in the concentration of L. innocua 10 days after inoculation. E. coli was detected in water samples up to 7 days after inoculation and L. innocua was detected up to 28 days by direct enumeration. Both strains were recovered from enriched samples up to 28 days after inoculation. These results demonstrate that E. coli and L. innocua strains are able to persist on lettuce after a single contamination event up until the plants reach a harvestable state. Furthermore, the persistence of E. coli and L. innocua in water for up to 28 days after inoculation illustrates the potential for multiple plant contamination events from stored irrigation water, emphasising the importance of ensuring that irrigation water is of a high quality. View Full-Text

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Posted in E.coli, escherichia coli, Food Micro Blog, Food Microbiology, Food Microbiology Research, Food Microbiology Testing, Listeria, Listeria innocua, microbial contamination, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Research

Information – Selecting and Serving Produce Safely

Posted on September 9, 2021 by | Leave a comment

FDA

As you enjoy fresh produce, follow these safe handling tips to help protect yourself and your family.

Fruits and vegetables are an important part of a healthy diet. Your local markets carry a wide variety of nutritious fresh fruits and vegetables. However, harmful bacteria that may be in the soil or water where produce grows can come in contact with fruits and vegetables and contaminate them. Fresh produce may also become contaminated after it is harvested, such as during storage or preparation.

Eating contaminated produce can lead to foodborne illness, often called “food poisoning.” So as you enjoy fresh produce, follow these safe handling tips to help protect you and your family.

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Posted in Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Testing, Food Safety, microbial contamination, Microbiological Risk Assessment, Microbiology, Microbiology Investigations

Research – Germany reveals insights from enlarged Campylobacter surveillance

Posted on September 8, 2021 by | Leave a comment

Food Safety News

German experts have presented results so far from increased surveillance of Campylobacter infections.

In Germany, around 60,000 cases are reported every year. Mainly contaminated food of animal origin are identified or suspected as sources of infection.

Intensified molecular surveillance of Campylobacter from human infections at the National Reference Center (NRZ) for Salmonella and other Bacterial Enteric Pathogens at the Robert Koch-Institut (RKI) was set up in 2019.

In 2020, the NRZ received 1,299 Campylobacter isolates from human infections for surveillance and subtyping. There were 55,831 reported cases in the same year. More than 25 different laboratories contributed a diverse range of isolates. More than 80 percent were Campylobacter jejuni and 15 percent Campylobacter coli.

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Posted in Campylobacter, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, microbial contamination, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Research

Information – Fruits and Vegetable Safety

Posted on September 8, 2021 by | Leave a comment

Click to access fruit-veggie-safety-H.pdf

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Posted in Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Testing, Food Safety, microbial contamination, Microbiological Risk Assessment, Microbiology, Microbiology Investigations

Research – Impact of Interventions on the Survival of Salmonella enterica I 4,[5],12:I:- in Pork

Posted on September 7, 2021 by | Leave a comment

Journal of Food Protection

A mixed culture of different isolates of Salmonella serovar I 4,[5], 12:i:- was compared to a mixed culture of reference Salmonella serovars as well as non-pathogenic Escherichia coli surrogates.. The two groups of Salmonella were compared for their resistance to commonly used pork carcass interventions, survival in ground pork and thermal resistance in ground pork. There were no observed differences between the response of the two different groups of Salmonella serovars and the non-pathogenic E. coli surrogates within intervention type.  There were no observed differences in the recovery and survival of the two different groups of Salmonella serovars in pork which had been treated with interventions, ground and stored at 5 o C for two weeks. Finally, there were no observed differences in heat resistance between the two different groups of Salmonella serovars in ground pork which had been treated with interventions, ground and stored at 5 o C for two weeks. However, there were observed differences in heat resistance in both groups of Salmonella serovars associated with refrigerated storage. The heat resistance of both groups of Salmonella serovars decreased after refrigerated storage. The results of these experiments demonstrate that there were no observed differences between the responses of Salmonella serovar I 4,[5], 12:i:- when compared to the reference Salmonella serovars to commonly used interventions in the pork industry, and therefore do not present a unique challenge to the pork industry.

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Posted in Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, microbial contamination, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Research, Salmonella