36 Microbial Pathogens
Learning Objectives
Give examples of microbial pathogens and the sanitation and health risks thereof
Microorganisms
There are 5 types of microorganisms:
Bacteria, Yeast, Moulds, Parasites and Viruses
Microorganisms can be beneficial (i.e. yeast for brewing and baking, bacteria in yogurt, etc.). Some microorganisms may just cause spoilage while others cause disease.
Pathogens
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Listed below are common pathogens:
Salmonella
Foodborne bacteria with 1,300 types known. One of the most severe infections caused by salmonella is typhoid fever. The main sources and carriers of salmonella in the food industry are most poultry, eggs and cracked eggs, shellfish, raw milk, and service workers with unwashed hands. People and animals may be carriers without showing any symptoms.
Safeguards:
- Cook products to an internal temperature over 60°C (140°F) for 12 minutes to kill salmonella.
Escherichia coli (E. coli)
A bacterium found naturally in the intestines of humans or other animals. The strain common to the meat and food industry is E. coli 0157:H7. E. coli does not cause a disease and is not considered parasitic because its source of food is the body waste in the intestinal tract. However, should E. coli gain access to the kidneys, bladder, or other internal organs, it can become parasitic and produce infections that can turn fatal. E. coli outbreaks associated with domestic animals (mainly beef) have strained the meat industry when it has been discovered in ground meat supplies. In addition, E. coli has occurred in milk, cheese, and related foods as well as in plants and plant products irrigated with contaminated groundwater supplies.
Safeguards:
- Understand that E. coli cannot be destroyed by freezing.
- Cook products such as ground meat to a core temperature of 71°C (160°F) to kill E. coli.
- Follow and enforce good personal hygiene (hand washing) after using the toilet.
- Follow industry safeguards to prevent contamination during the harvesting of animals, especially during the removal of the hide, which is often covered in fecal matter. (One large harvesting plant in Alberta has a state-of-the-art hide wash to help eliminate contamination prior to removal of the hide.)
- Take the preventive measure, which should now be a common practice, of carefully trimming meat surfaces on sub-primals that are near the aitch bone portion of the pelvis and anal canal. These areas are located on the hip and sirloin, especially on the hindquarters of beef carcasses and pork and lamb legs.
Clostridium botulinum
an anaerobic microorganism (it grows without air) which forms spores that exist over a wide range of temperatures. The organism itself does not cause illness, but the toxin it produces is one of the most deadly known to humankind. The spores can survive in frozen, raw, and precooked food. Although it is not a frequent cause of illness, it is considered the most serious to deal with in the food industry. This nasty organism is found in the intestines of humans and animals and in soil and streams. The major source of botulinum is swollen and damaged canned products and/or air-tight packages such as vacuum-sealed products with low acid foods such as beans, fish, and meats.
Safeguards:
- Understand that the spores of the organism are very heat resistant and can survive boiling temperatures.
- During any food packaging process, ensure product is heated to a core temperature of 82°C (180°F) for 20 minutes to kill any toxins.
Listeria Monocytogenes
Listeria is commonly found in soil, stream water, sewage, plants, foods made from milk, and processed foods such as hot dogs and deli meats. It can also be found in uncooked meat and vegetables and fruit such as apples and cantaloupes. Animals can also be carriers. Contamination may occur after cooking and before packaging. Listeria is responsible for listeriosis, a rare but potentially lethal foodborne infection. Listeria can grow in temperatures from 4°C to 37°C (40°F to 96°F), which is human body temperature. The bacterium is known to cause meningitis, a potentially fatal disease.
Safeguards:
- Implement thorough cleaning practices especially for equipment used to slice or needle meats (tenderize). This includes fully disassembling equipment, then scrubbing, rinsing, sanitizing, and air drying.
- Keep all floors and drains thoroughly cleaned; these areas are often overlooked and are known to be breeding grounds for listeria.
- Institute a deep-cleaning plan for any processing area as part of a sanitation program. This involves committing to extensive cleaning of the whole work area several times throughout the working year, including cleaning floors, walls, and drains and the complete disassembly of all equipment.
https://opentextbc.ca/meatcutting/chapter/diseases-associated-with-meat/
Bacteria/ Microorganisms Growth
The following factors encourage bacteria growth:
- Temperature: most microbes grow best between 4C-60C. We call this the danger zone. This is why we cook certain products (ground beef is cooked to 165C) and refrigerate or freeze others. Cooking can kill most microbes and refrigeration and freezing will slow the growth.
- pH (Acidity) – most microbes grow between pH 4-7
- Water Activity (Aw) – this is amount of water that is available in a food for microbes.
- Air – some microorganisms require air to grow and others can grow without it (aerobic or anaerobic). Facultative anaerobes can grow in both conditions.
- Nutrients – bacteria eat everything we eat!
Cleaning is the process of removing soil and debris from the surface. Sanitizing is the process of reducing the microbial load on a surface. A dirty or non-clean surface cannot be properly sanitized.
Proper sanitation is a critical step in reducing or eliminating pathogens in a processing facility. Sanitation is different for different industries. Most sanitation is wet sanitation. However, dry sanitation is often used in the milling and bakery industries. The presence of water can cause harmful mold and yeast growth in dry processing environments.
Dry cleaning is ideal for food processing plants which require little to no moisture as moisture can grow pathogens and also ruin the food. It is an effective method for reducing microbial growth and pests, but it does not fully sanitize an area. Dry cleaning is done using equipment such as brushes, brooms and vacuums. Like always in the food processing industry, cross contamination is a large concern. It is important to have measures in place to properly label the tools so they are only ever used for their specific purpose. For example, a brush used to clean a counter should not also be used to sweep the floor. It is also important to start a dry cleaning from the top (ex. countertop or shelf), and work down to the bottom (ex. floor).
Priority Allergens
Severe allergic reactions (e.g. anaphylactic reaction) occur when the body’s immune system strongly reacts to a particular allergenic protein or irritant. These reactions may be caused by food, insect stings and medications.
Health Canada, the Canadian Food Inspection Agency (CFIA), allergy associations, and the medical community have identified the key substances most frequently associated with food allergies and allergic-type reactions. These substances are often referred to as priority food allergens. Health Canada and CFIA have developed a series of pamphlets with information for consumers about each of the priority allergens:
- Eggs
- Milk
- Mustard
- Peanuts
- Crustaceans and molluscs
- Fish
- Sesame seeds
- Soy
- Sulphites
- Tree nuts
- Wheat and triticale
It is important to follow the procedure indicated by the food processing plant when cleaning and sanitizing, dealing with, and labeling the allergens. Some things to be aware of with allergen control are:
- Approved suppliers
- Proper segregation or separate storage of non-allergen from allergen containing ingredients
- Identify allergens on label (color coding)
- Staff training
- Adequate cleaning
- Batch traceability
This information was taken from the government of Canada website. A complete copy is available for free from https://www.canada.ca/en/health-canada/services/food-nutrition/food-safety/food-allergies-intolerances/food-allergies.html