Analysis of factors that inhibit the growth of Listeria

The NVWA asks producers to control the risk of Listeria monocytogenes in their products. The interpretation of Regulation EC 2073/2005, as described in Info sheet 85, applies as a guideline. With the help of the decision tree on page 20, it can be decided whether or not a certain food product constitutes a risk. In order to do so, analysis of pH and water activity (aw) is necessary.

Predictive models ComBase and FSSP Listeria

If Listeria growth in the product seems possible, on the basis of pH and aw, establishing proper criteria for shelf life is mandatory. Predictive models such as ComBase and FSSP are acknowledged tools for this purpose. FSSP is used most frequently because this model is more complete than ComBase. It contains all of the important factors that inhibit the growth of Listeria, such as pH, nitrite, phenols from smoke, salt in the water phase and organic acids. Nutrilab can analyse all these components with methods that fit the FSSP model. One example is the analysis of phenols.

Phenols vs the growth of Listeria

The smoking of products, such as fish and meat products, inhibits the growth of Listeria. Phenols are responsible for this. With 15 ppm (mg/kg) phenols, the shelf life can be doubled. Different methods are used by several laboratories for determining the amount of phenols in a product. These all result in very different outcomes. Nutrilab uses the method that best fits FSSP.

Currently, Nutrilab has a great deal of experience with modelling using FSSP. Additionally, we are conducting challenge tests with which we are going to test the growth speed of Listeria in practice. 

If you want to know more about controlling the Listeria risk, the necessary analysis package or challenge tests, please contact Gerard Kramer via +31(0)183-446302 or [email protected].

References
http://fssp.food.dtu.dk/
https://www.combase.cc/index.php/en/