A new research project seeks to develop a mathematical model which predicts the growth of Listeria bacteria in cheese. The project will be carried out by ph.d. student Per Sand Rosshaug at LIFE, the Faculty of life sciences at the University of Copenhagen, in cooperation with DHI.
The model facilitates and shortens the process of experiments e.g. in relation to process- and product development, and can be used in the assessment of the shelf life of the product. Focus is on Listeria in blue and white mould cheese which in Denmark is produced by Arla under the name of “Klosterkrone” but probably it can be used with other kind of cheese and bacteria. Per Sand Rosshaug expects to use the ECO Lab technology from the MIKE package and to further develop the ECO Lab functionality for instance by coupling neural networks with ECO Lab.
Artificial neural networks are a kind of artificial intelligence able to estimate unknown variables from recognising a pattern based on historical patterns. In relation to this project the neural networks should predict the growth rates of Listeria with different combinations of the environmental parameters.
A serious problem concerning food safety
Listeria bacteria represent a major problem concerning food safety. The bacteria can cause acute blood poisoning, meningitis and infections of children immediately before or after delivery. Knowledge about growth, survival and deactivation of this pathogenic organism is hence very important.
In dairy products the bacteria can be found in the raw milk, but there is also a risk of contamination of the milk or the cheese later during the process.
The legislation of the EU suggests the use of mathematical modelling in the assessment of the microbiological safety in food products, but it hasn’t gained ground in the food industry yet. In particular this is due to the lack of user friendly software which allows the user to easily perceive the information of the model.
Many parameters influence the growth
Several parameters need to be considered when estimating the growth of Listeria. The temperature of the product, the water activity, the pH, the carbon dioxide, the organic acid, the nitrite, natural antimicrobials, essential oils and also the interaction between lactic bacteria and Listeria.
No model exists today that describes the combination of all these parameters and also considers the spatial variation of these parameters in the product.