Pasteurized milk products, such as fresh milk, cheese, and yogurt, are among the food categories with a high frequency of consumption, making monitoring and compliance with hygiene and safety rules particularly important for public health. This is compounded by recent legislative reforms that have increased the shelf life of milk, resulting in the need to redesign and adapt the quality and safety management system.
The heat treatment of pasteurization applied to raw milk is considered sufficient to kill all forms of bacteria, but it cannot control the spores of bacilli that may be present in it. In particular, the presence of Bacillus cereus spores in raw milk, which result from on-farm contamination of the milk (soil, grass, manure, feed, milking, and collection equipment), is considered of paramount importance for the shelf life of the final product. Spores survive pasteurization, and in special cases (cold-hardy strains), their growth is not completely inhibited by refrigeration. If the temperature conditions of the cold chain (from production in the factory to consumption) allow it, the growth of B. cereus may adversely affect both the quality and safety of the product before the end of its shelf life.
It is widely known that B. cereus can potentially cause two types of food poisoning: the emetic type and the diarrheal type. At the same time, it can cause a change in the structure of milk, known as ‘sweet coagulation,’ which leads to the organoleptic rejection of pasteurized milk products.
The literature data above are in full agreement with the experience of the Greek dairy industry, which considers B. cereus as one of the most important safety and quality problems in pasteurized milk products.
Currently, most B. cereus control systems in milk, based on classical microbiological analyses of the final product, cannot guarantee consumer protection since complete control of the products is economically and practically impossible. Moreover, traditional sampling does not take into account factors that have a significant impact on safety and quality. Finally, the classical control approach is deterministic, ignoring the high variability of factors that significantly influence microbial growth and determine the degree of risk, such as the initial level of contamination, temperature conditions during distribution and preservation, and shelf life. Therefore, the necessity of introducing a modern control system for B. cereus in milk, mainly based on prevention rather than control of the final product, is highlighted.
The development of new technologies in the field of food microbiology now allows their integration into the production process. The technologies of ‘omics’ and ‘quantitative microbiology’ are two scientific fields that have been developing rapidly but autonomously in recent years. The use of omics technologies, after appropriate bioinformatics analysis, can lead to the rapid identification of markers of microorganisms involved in the final quality and safety of food. In addition, quantitative microbiology can provide, through mathematical models, accurate predictions of the influence of environmental parameters (e.g., temperature) on microbial behavior. The combination of Risk Analysis technologies, as proposed by the World Health Organization (WHO) and the European Food Safety Authority (EFSA), is also possible.
Based on the needs created by the above situations, the scope of the research project is the development and combined application of genomic, transcriptomic, and mathematical prediction tools as the basis of an active risk management system for B. cereus in Greek milk.
In summary, the objectives of the project are as follows:
– To study the presence/concentration of B. cereus in raw and pasteurized milk and to isolate B. cereus strains.
– The phenotypic and molecular characterization of B. cereus strains.
– Identification of molecular markers related to the psychrotrophic nature, pathogenicity, and spoilage potential of B. cereus through
