Efficacy of a Continuous Dean Flow UV-C System in Almond Milk Pasteurization Using Computational Fluid Dynamics and Biodosimetry

Abstract A continuous Dean flow UV-C system was designed using fluorinated ethylene propylene tubing with UV-C transmission ≈ 60% wrapped in a serpentine path to improve axial mixing with a Dean number > 140. The microbial inactivation efficiency of the system was evaluated using Salmonella Typhimurium, E. coli O157:H7, Staphylococcus aureus, Saccharomyces Cerevisiae, and T1UV inoculated in almond milk (AM) and treated at various fluence levels at an optimized flow rate of 515 ml/min. In addition, a detailed examination of the velocity magnitude at various locations in a dean flow system, especially at the bends, was quantified. The findings indicate that a reduction > 4 log was attained for all specified microorganisms with a reduction equivalent fluence of 22.05 mJ/cm². Additionally, computational fluid dynamics were employed to examine the velocity magnitude and incident radiation field within the tubing. In summary, the system demonstrated effectiveness in inactivating target microorganisms present in almond milk.