SIKKER ­– Harnessing microbial synergies for safer dairy

Dairy foods represent one of the top categories, in terms of food loss and waste, and it is estimated that approximately a quarter of all dairy products are lost at the production level or wasted at the retail or consumer level, annually. Dairy products are susceptible to spoilage by various microorganisms, both during and after manufacturing, which has large economic consequences for the dairy industry. Equally important to consider, are the presence of pathogenic microorganisms, that may cause disease or even death. The aim of SIKKER is to investigate the potential of using a naturally occurring antimicrobial substance (reuterin) to prevent unwanted microbial growth in dairy products.

By: Grith Mortensen

In the European Union, as much as 0.4% of all foodborne outbreaks are due to contaminated cheese, and thus efficient measures to control growth of undesired microorganisms are needed. Reuterin is an antimicrobial substance produced by the probiotic lactic acid bacterium Lactobacillus reuteri. Research has shown that Lb. reuteri can prevent growth of both spoilage and pathogenic microorganisms often associated with dairy products. Reuterin is effective against Listeria monocytogenes, a potentially deadly pathogen, which has been found in bulk tanks used for milk storage and Staphylococcus aureus, the most frequent cause of mastitis, which is also responsible for foodborne outbreaks. Reuterin is also active against fungi, and yeasts contaminating fermented milks and other dairy products.

The researchers in this project will screen lactic acid bacteria that can produce glycerol from milk-based substrates as Lb. reuteri produces reuterin in the presence of glycerol. In addition, they will characterize the glycerol-producing bacterial strains in order to learn more about the metabolic pathways. Finally, they will try to produce reuterin directly in the product and investigate the bioprotective effect. This will be carried out in small-scale cheese trials first, - if promising results are obtained it will subsequently be scaled up into real dairy scale production.

The project will contribute with knowledge on how to extend shelf life of dairy products, avoid food waste, and how to use residual streams without jeopardizing food safety.