The 5 Most-Feared Pathogens for Dairy Foods
Thousands of companies across the world manufacture food products that are wholly comprised of dairy, or contain dairy elements.
As with any classification of food product, threats to food safety and quality can occur in dairy when there are infractions during production, handling or transfer of products.
These threats can result in the growth of pathogens in products, which in turn can harm consumers. Pathogens cause disease when ingested, to the tune of more than 25,000 confirmed cases of foodborne illnesses in people across the U.S. in 2016 (CDC.gov).
With that in mind, here’s an overview of the five most-feared pathogens that can occur in dairy foods, how and why they occur, and preventive measure to avoid them.
1. Salmonella species
There are more than 2,400 known species of Salmonella, and all are considered pathogenic to humans. Salmonella is a zero-tolerance organism in all food products because doses of less than 1,000 cells can be infective. For every illness linked to Salmonella, the Center for Disease approximates that an additional 30 cases are un-diagnosed.
This pathogen differs from some others on the list when it comes to food products. Salmonella is extremely heat tolerant particularly in low moisture and high fat foods, meaning it can survive during the cooking or baking processes that would typically inactivate pathogens.
Sources: Unpasteurized milk, insects, birds, soil, humans, environmental hazards
2. Listeria monocytogenes
Just a few Listeria cells can prove harmful to infants, the elderly and immuno-compromised individuals. Less than 100 cells is considered an infective dose, and the organism thrives in cold environments such as refrigerated manufacturing environments and cold storage. These environmental and storage conditions are typical for the production of dairy products.
Being thorough in both product preparation and facility sanitation is key to preventing Listeria. It can be readily destroyed by pasteurization and cooking in the food product itself, but proper (lethal) sanitation of equipment and surfaces will protect ensure products are safe from post processing contamination.
Sources: Unpasteurized milk, soil, sewage, decaying plant material, rodents and other animals, poorly designed equipment
3. Cronobacter sakazakii (Enterobacter sakazakii)
The presence of this pathogen is primarily associated with dry milk powders that have been compromised. The natural source or habitat for Cronobacter is not known but it has been isolated from dairy powders and infant formula, cereals, and starchy foods. Dry conditions must be maintained in dryer conveying equipment, powder storage and bagging areas, or moisture will pose the threat of activating Cronobacter.
Like Listeria, Cronobacter is susceptible to pasteurization. After the pasteurization process, good personal hygiene on the part of the production staff and alignment with GMP’s is crucial to maintain the integrity of dried dairy powders.
Sources: unknown; environment-driven
4. Staphylococcus aureus (toxin)
Staphylococcus is tolerant to salty and dry conditions, making cheese products especially susceptible for contamination. Food handling behaviors and hygiene after pasteurization prove imperative for protecting dairy products from Staphylococcus aureus and toxin production.
Similar to Cronobacter, maintaining dry conditions throughout the dry milk production facility is important. The dryer conveying system, powder storage and bagging areas need to be free from standing water to help protect product from the introduction and growth of Staphylococcus.
Sources: skin, nasal passage, mastitic cows
5. Bacillus cereus (toxin)
This organism produces heat-resistant endosopores that can be activated for growth of vegetative cells in a wide range of temperatures. Toxin production initiates after spore activation and vegetative cell growth. It’s considered a moderate pathogen, but is of primary concern for infant nutrition because of their underdeveloped immune systems.
Dairy products that are heat-treated, and then held at elevated temperatures for long periods of time, can be at risk. Temperatures should be at or above 140 degrees Fahrenheit to control growth or product should be cooled and stored quickly.
Sources: Milk, soil, rice and other grains, vegetables, meat