Understanding and predicting bacterial behaviour in foods is vital to establish food safety. Although in the past most microbiological studies were conducted in liquid systems (broths), it is well known that bacterial behaviour changes fundamentally when grown in structured, solid-like environments. Additionally, the food industry is evolving towards a more sustainable approach, following consumer demands for more healthy and more natural food products. Therefore, the production as well as the composition of food products is changing. Examples of such changes are the reduction of fat, salt or sugar contents, or the replacement of commercial artificial food additives and common food preservation technologies with alternative more natural or milder approaches. However, many of these ingredients, additives and technologies also serve food safety purposes. Therefore, emerging mild preservation technologies, such as natural antimicrobials and non-thermal processing methods, are being recognised as potential alternatives to standard food safety protocols. However, these newly emerging mild technologies are generally less effective than traditional approaches and show to have greater potential when used in combination with other treatments. To explore the potentials of novel ‘hurdle approaches,’ additional studies are needed to provide a more comprehensive understanding of their action, in systems that can mimic the structural and biochemical composition of foods.

           In this thesis a novel tri-phasic 3D food model system of tuneable properties was developed and fully characterised. Thereafter, a systematic assessment of the impact of fat concentration on different cutting-edge mild preservation approaches to control pathogenic bacteria took place.

More specifically, structured complex food model systems were developed and used for fundamental microbiological studies of single- and co-cultures of foodborne bacteria, including L. monocytogenes, E. coli, L. lactis and P. aeruginosa. The macroscopic growth kinetics and microscopic spatial organisation was used to determine changes in their behaviour towards bacterial antagonistic mechanisms, natural antimicrobials (grape seed extract and nisin) and a non-thermal preservation treatment (cold atmospheric plasma).

The findings of this work illustrated the importance of conducting microbiological studies in more realistic food model systems to be able to draw conclusions for the environment they mimic. Moreover, our data highlighted the promising potential of novel preservation techniques in enhancing food safety, with careful consideration of food structure, complexity, and environmental conditions.