LISTERIA: A NEW CASE STUDY, IN A DIFFERENT BATTLEFIELD
Hello everyone and welcome again to our Amerex Blog!
As we have mentioned in our previous Blog posts, Listeria monocytogenes, a common bacteria found in the food industry as well as the disease it causes -listeriosis-, are back in the spotlight. As per the information gathered in the last few months, even though it is related to the meat industry, it poses a threat to many other sectors as well.
Therefore, the objective of this Blog post is to ensure that everyone is conscious of another battlefield when it comes to Listeria: dairy industry. Specifically, and as a case study, we would like to explain a very interesting situation that happened at Amerex. Let’s have a look!
Feta cheese is a Greek origin cheese made mainly from goat milk. It is considered a “ready-to-eat meal” by the AESAN as it doesn’t require any cooking or processing to reduce or eliminate the presence of Listeria monocytogenes to bring it within the acceptable range. This is the main reason behind the prevalence of this type of bacteria in this cheese. Furthermore, according to integrated mathematical models in ComBase, an online tool created by a collaboration between Tasmania University and the USDA-ARS for quantitative food microbiology, feta cheese is classified as a food where the growth of Listeria monocytogenes is possible due to its pH, aW and lactic-acid concentration.
Nevertheless, numerous research papers published in major scientific journals proved that feta cheese, in particular, prevents the development of this family of bacteria and, in addition, leads to a progressive inactivation of microorganisms. These researches fool the industry into believing that feta cheese meets the necessary food safety requirements of food safety for Listeria monocytogenes for its entire shelf-life, however, it is important to bear in mind the significance of the Hazard Analysis Critical Control Points (HACCP), such as: contamination level of raw materials, specific processing conditions, etc… All of these are included in the barriers we discussed in the previous post from our Blog.
In fact, these HACCP guidelines contradict the information in the aforementioned scientific journals. The moment any raw material, mainly pasteurized milk, is contaminated during fermentation, it provides ideal conditions for the proliferation of the infectious agent within the first two days. Considering this growth, under certain circumstances, some strains of Listeria monocytogenes can survive a standard pasteurization process; this could be a cause of alarm for human health safety.
It should be noted that the low temperature and low pH conditions during storage provide an ideal environment for the stabilization of the bacteria in high concentrations. In addition, even in temperatures starting 1.7 ºC and above, it cannot be guaranteed that the cheese is free of pathogens. In addition, the regulation parameters specify that, in order to prove that Listeria monocytogenes does not grow in a product, it would have to meet one of the following requirements: pH≤4.4, or aW≤0.92, or a combination of both parameters: pH≤5.0 and aW≤0.94.
Since feta cheese has a pH of 4.4-4.6 and aW of 0.94-0.95, it barely fits within these parameters and it is likely to exceed in some batches. Therefore, taking into account the temperature mentioned above, we could be facing potential threats.
Following this explanation and the previous post from our blog, it is key to try to manufacture a 100% safe food item. It is clear that there is no single formula for achieving this level of absolute safety. However, the more barriers between the pathogen and our product, the better.
This is a problem that affects not only meat and dairy industry, but also other sectors of the food industry that are normally considered exempt for this threat.
There is always something to be done for improving safety. We invite you to share your own concerns, whatever industry you belong to, and we will provide personalized assistance to boost your confidence regarding the launch of products.
Here at Amerex we design our preservatives with specialized technology and are constantly developing our know-how, to achieve one of our main objectives: building a set of barriers that are unbreakable for any harmful microorganism.
Once again… Here we are!
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