When considering microorganisms in food, they are frequently associated with beneficial processes. This is no coincidence, as many of them are essential in the production of foods we consume daily. Examples include fermented products such as yogurt, made using lactic acid bacteria like Streptococcus thermophilus and Lactobacillus bulgaricus; beer, produced with the yeast Saccharomyces cerevisiae; and cheeses, where in addition to lactic acid bacteria, fungi such as Penicillium roqueforti in roquefort cheese or Penicillium camemberti in camembert also play a role. Beyond their technological function, some of these microorganisms can also provide health benefits by contributing to the balance of the gut microbiota. In this context, microorganisms are clearly allies.
However, not all of them are harmless. Pathogenic microorganisms can contaminate food and cause illness when consumed. Their presence may result from multiple factors, including contact with animals, the use of contaminated water, or poor hygiene practices during food production and handling. Among them, Listeria monocytogenes stands out as a major concern, responsible for severe foodborne outbreaks and particularly dangerous for vulnerable populations. Alongside it, bacteria such as Salmonella, Campylobacter, and certain strains of Escherichia coli are among the leading causes of foodborne infections in Europe.
According to the European Food Safety Authority (EFSA), there has been an increase in these infections in recent years, partly linked to changes in our eating habits. The consumption of ready-to-eat foods has become increasingly common, including packaged salads, cut fruit, hummus, gazpacho or smoked salmon. Their main advantage is convenience, but they also pose a higher risk, as they are consumed without prior cooking.
This is where temperature plays a key role in food safety. Cold storage, whether through refrigeration or freezing, does not eliminate microorganisms but slows their growth, preventing them from reaching levels that may pose a risk to consumers’ health. In contrast, keeping food at room temperature promotes bacterial multiplication. Therefore, proper storage and maintaining the cold chain are essential. Heat, on the other hand, is the most effective way to eliminate pathogenic microorganisms. Ensuring that food reaches adequate internal temperatures during cooking is crucial for safety. This is especially important not only at home but also when transporting food for consumption outside, such as at the beach or during excursions.
In summary, microorganisms in food can be both allies and enemies. The key lies in understanding their role and applying proper handling and storage practices to ensure food safety.
Sources:
European Food Safety Authority (EFSA). (2025, 8 december). Serious Listeria infections rising in Europe, EU report warns. https://www.efsa.europa.eu/es/news/serious-listeria-infections-rising-europe-eu-report-warns
Postdoctoral researcher in the Department of Food Science and Technology at the University of Córdoba, where she has been conducting her scientific activity since 2021 within the HIBRO research group (AGR-170). She obtained her Bachelor’s Degree in Food Science and Technology and her Master’s Degree in Agri-food Studies from the same institution, and earned her PhD in 2025 within the Biociences and Agri-food Sciences doctoral program. Her doctoral research specialized in the application of sustainable biopreservation methods and predictive models to optimize the quality and microbiological safety of plant-based matrices such as strawberries and tomatoes.
Her research activity focuses on food safety, particularly on the development of biopreservation strategies applicable not only to plant-derived products, but also to dairy, fishery, and meat sectors, with the aim of ensuring food safety and extending shelf life under food loss and waste reduction criteria. Within this framework, her scientific career has been distinguished by the valorization of agricultural residues for the isolation of bioprotective microorganisms and the synthesis of high-value biomaterials, such as cellulose and (ligno)nanocellulose, which are essential for the development of functional and sustainable packaging materials.