Tag Archives: bacteria

Foodborne Bacteria: Do You Know How They Grow?

Food safety concerns are on all food manufacturers’ minds (and, honestly, probably in their dreams too), so it is critical to know how bacteria grow.  Armed with that knowledge, we are better able to stay ahead of bacterial contamination in the food manufacturing facilities.

Petri dish with bacteria.

Petri dish with bacteria. Source: processingmagazine.com

Often, when I was in the plant environment, I would refer back to a case study put together by the Royal Society for Public Health in 2010. It laid out some excellent basics on growth factors for bacteria in a concise manner that readers of The Wide Line may appreciate.

The RSPH states, “In order to grow, bacteria require a source of nutrients, an appropriate atmosphere, neutral or alkaline conditions, available moisture and an appropriate temperature. (In turn), the nutrient source needs to have available moisture, a source of energy, nitrogen, vitamins, and minerals.” A large number of bacteria are able to grow with or without oxygen. Some bacteria (obligate aerobes), will only grow if oxygen is present. Other bacteria (obligate anaerobes) will only grow in the absence of oxygen.

The RSPH’s “Growth Requirements of Bacteria” section continues: “Most bacteria grow best in a neutral or alkaline environment. Bacteria do not grow well in foods which are too acidic (with a pH of less than 4.5).”  So, the more acidic the food, the less likely it is to support the growth of bacteria.  In addition, foods that are dried or high in salt or sugar have a reduction in available moisture content, and bacteria will grow poorly on these foods.

Finally, “Most bacteria will not grow in cold conditions, or will only grow and divide slowly. High temperatures will also inhibit the growth of bacteria.”  For example, most food poisoning bacteria die when exposed to a temperature of 70°C for two minutes or more. The optimum temperature range for the growth of most bacteria is 5°C to 63°C, which is known as the ‘temperature danger zone’.

The RSPH concisely acknowledges that there are multiple areas in all food production facilities that need to be assessed for risk regularly, as well as monitored daily in order to prevent microbiological product contamination. All processing steps have the potential to increase the chance of microbial corruption.  Nelson-Jameson carries food safety products that assist with control and surveillance in every step of the production process—from ingredient receiving through manufacturing, storage, and shipping of finished products.  Contact a sales representative today to find out how Nelson-Jameson can help strengthen your food safety prevention and protocol.

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Testing the Water

j0444789What is the difference between water activity and water “moisture” content? Well, it all depends on what you want to achieve. Do you want to monitor the amount of water and dry matter present in a product? Or do you want to increase and monitor the shelf stability of a product?

“Water ‘moisture’ content is the amount of water contained in a product”. Measuring water “moisture” content is better used to determine quality of the process. For example, if the product is a cheese powder that is spray dried, it is common practice to measure the water “moisture” content to determine yield and to ascertain if your drying process is running according to the diagnosed plan.

Water activity is defined as the measurement of the availability of free water for biological reactions—especially the biological reactions that can make humans and animals very sick.  Water activity is more critical in the food industry. Bacteria love water; gram-negative bacteria like E.coli need a minimum of .97 moisture content for growth, and the Staphylococcal toxin produced by Staphylococcus aureus only needs a minimum of .93 for growth. To put this into perspective, know that pure water’s moisture content is 1.00. Thus, it is critical for food manufacturers to know and monitor the water activity before, during, and after manufacturing for safety. See the table below for the water activity and content levels of common foods:

Water Activity of Common Foods (aw)

fresh meats and fish:                     0.99

moist cakes:                                       0.90-0.95

soy sauce:                                           0.80

jams, marmalades, jellies:            0.75-0.80

dried spices, milk powder:           0.20-0.60

Water Content of Common Foods (%)

apples:                 84

peppers:              92

salami, beef       60

dried fruit            31

wheat flour        11

Water activity is crucial to food safety. Microbes are everywhere, and will find any way possible to a food source, ultimately causing spoilage. Moisture analysis monitoring processes are set up to eliminate as many microbes as possible, with the key to moisture control and water activity being to find ways to bind the water so that it doesn’t allow microbes to find a food source—thus extending a product’s shelf life. Contact one of Nelson Jameson’s product specialists today to discuss your moisture analysis and water activity needs.

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Water Savings and Effective Cleaning? Full Steam Ahead!

steam cleanerSteam: this is not really a topic most would like to think about as the temperature climbs. However, it is a topic you may want to take note of though for the next few moments, as it could affect your bottom line this summer and beyond. Steam cleaning is a powerful method used to combat germs and to sanitize surfaces in domestic, commercial, and industrial spaces.

For food operations, there are several key aspects of steam cleaning that are ideal for industrial settings. First, steam cleaning is effective; it kills germs and bacteria. It also attacks grease and cleans surfaces thoroughly. Second, it is cost-effective. Using steam means less chemicals in your plant and it means merely adding water to your steam cleaner to effectively get the job done. Third, the right steam cleaner can reduce your manual labor costs.

If you would like to know more about steam cleaners, and even some currently available close-out specials for your operation and for information on the potential uses and efficacy of steam cleaners, contact our Processing & Flow Control Department at 800-826-8302.

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Making Sense of Listeria

Listeria monocytogenes (ABC News)

Listeria monocytogenes (ABC News)

The Centers for Disease Control estimates “approximately 1600 illnesses and 260 deaths due to listeriosis [infection caused by listeria] occur annually in the United States.” Even though responsible for fewer illnesses than other pathogens that are out there, listeria’s relatively high mortality rate (especially for certain segments of the population) naturally resonates with both consumers and food producers as a focus for concern. This has especially been the case with numerous high-profile listeria cases making headlines in the past several months.

Consumers may be surprised to find out that, opposed to being some isolated super-bug, “Listeria monocytogenes is commonly found in soil and water. Animals can carry the bacterium without appearing ill and can contaminate foods of animal origin, such as meats and dairy products.” Beyond that, food processors, understanding the threat that listeria presents, are especially concerned with the fact that: “When Listeria bacteria get into a food processing factory, they can live there for years, sometimes contaminating food products.”

So what is to be done to combat listeria?   Consumers can check out information on prevention from the CDC here and information from the FDA on proper handling of ready-to-eat, refrigerated foods here. The continuing presence of listeria in the headlines will no doubt also give pause for many food processors to review internal practices/standards, and review local, state, and federal resources to address the issue. Fortunately, risks can be minimized by utilizing programs and products that target some of the following areas: cleaning and sampling; ensuring proper temperatures when processing and handling food; and separating foods and parts of the production/preparation process to avoid cross-contamination.

To assist producers find products that can be of use, Nelson-Jameson has compiled a collection of products, including testing/sampling supplies, color-coded products, and numerous other offerings to both test for and prevent listeria concerns. You can check out these products here.

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An Aerobic Workout…In Your Food Operation

Source: CDC

Source: CDC

Aerobic bacteria (bacteria that require oxygen to live and thrive), like you and I, appreciate a chance to take a breath and reflect on plans for the future.  Single-cell life isn’t so easy, after all! Aerobic bacteria may wonder,” what will happen when I grow up/divide?” and, “Should I go into spoilage or perhaps foodborne illness?” Whatever the case, they sure are busy!

Their oxygen-loving (to merely tolerating) ways make them a desirable key target in the fight against contamination and product spoilage. Opposed to isolating and identifying specific aerobic bacteria, Aerobic Plate Count (APC) tests are utilized as general indicators of the presence of aerobic bacteria. Counting these aerobic colonies, as R. Dale Morton explains in the Compendium of Methods for the Microbiological Examination of Foods 4th Ed., “can be used successfully to gauge sanitary quality, organoleptic acceptability, adherence to good manufacturing practices and, to a lesser extent as an indicator of safety” (63).

Nelson-Jameson handles an array of APC products, including the recently launched 3M Petrifilm Rapid Aerobic Count Plates. The product “facilitates colony enumeration in just 24 hours for most food matrices / environmental samples and resists distortion caused by spreader colonies.”

To learn more about aerobic bacteria click here. For more information on APC products, including the new 3M Petrifilm Rapid Aerobic Count Plates email Jessica Goessl, Technical Sales Manager – Laboratory or call 800-826-8302.

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