May 30, 2024

Taylor Daily Press

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The irritated bacteria adapt

The irritated bacteria adapt

Having just one bacteria can cause a lot of misery. Preventing this is the challenge. Because microorganisms such as bacteria, fungi, and yeasts respond to stimuli and adapt. Suddenly it turns out that heating to 70 degrees is not enough to kill them.

Aldo Evers of Normec Foodcare specializes in microorganisms. According to him, microorganisms have a number of characteristics. They consist of one or more cells, contain organic matter, have metabolism (they can convert substance A into substance B), reproduce, and respond to stimuli from the environment.

According to Evers, the latter is the most important. “If I punch you with a passerby, I will get a reaction. Bacteria, fungi, or yeast do that too. They respond to stimuli and adapt. An example of this is antibiotic resistance. If people use antibiotics often enough, the bacteria learn to defend themselves.” If you do not complete the course of antibiotic treatment, you risk not killing all the bacteria. If one bacteria survives, it becomes resistant and the next treatment will have no effect.


Bacteria in food do the same thing. These also respond to stimuli and adapt. Evers points to a number of studies that prove this. In 1990, scientists discovered that exposure to cold could alter the incorporation of fatty acids into psychrophilic microorganisms, allowing them to grow faster and better after metamorphosis at low temperatures.
In 2021, Spanish scientists concluded that if salmonella is not sufficiently exposed to organic acids – generally preservatives such as citric acid and lactate – it can tolerate heat better. Finally, Evers points to a study done on Listeria in 2023. This study showed that standard heating of salmon, for 60 minutes at 70 degrees, is insufficient for some strains of Listeria. This means that the salmon product is not always safe.
Even Wikipedia says that bacteria adapt. bee Bacteria B.cereus “But recently, strains have also been found in pasteurized milk stored at 4-10 degrees Celsius. These psychoactive strains are able to produce toxins at these low temperatures.

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The models are no longer correct

Evers concludes that the knowledge exists, but not enough is being done with it. Because food companies often continue to rely on “old” models on paper. Evers thinks this is unwise, because: “If bacteria are exposed to sub-lethal stress – that is, they are stimulated but not enough to cause them to die – they will respond to it. Bacteria can become more resistant to salt, acids and antibiotics. As a result, they may “These bacteria are able to grow and survive in more extreme temperatures and conditions than our models no longer expect.”

Fewer obstacles

Aldo Evers: “Bacteria are barriers.”

(© Food Editorial)

Market demands increase this problem. “Consumers want to eat healthy,” Evers says. “This means less salt, less sugar, fewer or no preservatives, and less nitrite.” This increases risks to food safety. Evers compares it to barriers. “The hurdle runners do not fall at the first hurdle, only at the eighth. The same applies to bacteria. Obstacles such as salt, sugar and preservatives are reduced or completely eliminated. This increases the chance that the bacteria will survive the production process.”

Verification process

For the food industry, all this means that the verification process, for example for NVWA, BRC and IFC, is changing. There will be more requirements that need better proof. Evers briefly explains the validation process.

  • Step 1 guidance: Carefully plan the entire process, determine your microbiological load and identify your critical points
  • Step 2 Model: Outline on paper how the steps work, such as values, temperatures, and models
  • Step 3 Implementation: Does the process deliver the same value we expect on paper?
  • Step 4: Startup: Run all processes as shown
  • Step Five: Monitoring: Quality Program

The middle factor, implementation, must be addressed by the food industry in a different way. “Validation is becoming increasingly important,” Evers says. “It can’t be done on paper using just temperature, time and a model, it has to be done live.” He understands that this can be difficult. “It requires, among other things, more time, knowledge and other equipment.”

The food industry is advised to stay informed of the latest developments. “With a little research you will discover that the nature of the bacteria has changed. Also look critically at your process. Don’t think we’ve been doing it this way for years, so things must be fine. If the samples show there are problems with the product, “The first reaction is often to call the cleaning company, but if you’re dealing with bacterial resistance, that won’t help.”


According to Evers, there are many pitfalls in this field. Like corporate blindness. There is often a belief that things have been going well for years, so why should we change anything. Evers: “Things go well for ten years, until something goes wrong. And if you don’t do something, there’s a good chance the problems will pop up again ten years later.” He gives the example of the chocolate industry, where an outbreak occurs every five years, and always in a different factory. “Look at each other and learn from each other,” he advises.

The matrix and plants are also important. Evers gives the example of protein transport. “We are switching from animal proteins to plant proteins. This means that companies are receiving other bacteria that require a different approach. “You have to look at your system differently, and be critical of it.”

Another problem is the relationship between theory and practice. Evers illustrates this with the example of someone who creates a food safety system in an office, but never comes to the workplace himself. “Make sure the system you are using actually works.”

Finally, many companies find this topic difficult. It takes time and knowledge, while many food companies also face staff shortages. But the topic is too important to miss. So Evers says, “If you can’t figure it out on your own… ask for help!” Normec Foodcare is a company that can help with this. “We map out the process, simulate it, on site or in the lab, and come up with the right assessment,” concludes Evers.

This is a report on the lecture “How can microorganisms adapt to their environment to ensure food safety” by Aldo Evers from Normec Foodcare which was held during the food technology event on 15 May.

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