Impact of food matrix on pathogen heat inactivation in almond beverage and bovine milk during batch pasteurization

The present study aimed to provide a comprehensive understanding regarding the thermal inactivation of Listeria monocytogenes, Salmonella Typhimurium and Escherichia coli in bovine milk and a plant-based milk alternative-almond beverage. Thermal inactivation was performed with the method of batch pasteurization at 62°C for 30 minutes in a temperature-controlled water bath. The outcome for Listeria monocytogenes displayed a distinct difference in survival between the two liquid matrices. Bovine milk provided a more favorable environment for the pathogen’s survival compared to almond beverage. Specifically, Listeria monocytogenes remained detectable at a level of 3.5 log10CFU/mL until 20 minutes (T20) of batch pasteurization, while no viable cells were detected in the almond beverage, indicating that almond beverage did not support the pathogen’s survival under the applied thermal conditions. In the simulated Escherichia coli and Salmonella Typhimurium contamination experiment, the obtained results demonstrated that Escherichia coli did not preserve its viability in both bovine milk and almond beverage. The food matrix plays a key role in understanding the effects of batch pasteurization on pathogens, as it affects microbial behavior and survival, especially in hybrid products that combine dairy and non-dairy ingredients, like almond and bovine milk, which pose distinct microbial challenges. However, the present study intends to serve as a reference point, providing baseline insights that can guide and support future investigations involving a broader range of milk and plant-based drink products.