Optimization and evaluation of venturi tube reactors for non-thermal milk pasteurization using CFD method.

Area of Science:

• Food Science and Technology
• Fluid Dynamics
• Chemical Engineering

Background:

• Growing demand for preserving food's nutritional and sensory qualities necessitates advanced pasteurization techniques.
• Traditional heat-based pasteurization can degrade food quality.
• Non-thermal methods, such as hydrodynamic cavitation, present a promising alternative.

Purpose of the Study:

• To optimize a Venturi reactor design for efficient milk pasteurization using hydrodynamic cavitation.
• To maximize turbulent kinetic energy (TKE) and minimize energy loss within the Venturi reactor.
• To evaluate the effectiveness of the optimized design in reducing bacterial load while maintaining milk's nutritional and sensory properties.

Main Methods:

• Utilized computational fluid dynamics (CFD) with the k-ε turbulence model for reactor simulation.
• Employed the response surface method (RSM) to optimize key geometric parameters of the Venturi reactor (throat diameter, length, convergence/divergence angles).
• Conducted experimental validation to assess bacterial reduction and impact on milk composition.

Main Results:

• Optimized Venturi reactor dimensions: throat diameter (4.91 mm), length (13.15 mm), convergence angle (19.2°), and divergence angle (8.31°).
• Achieved maximized turbulent kinetic energy (TKE) (0.2438 m²/s² peak, 0.0305 m²/s² average) and minimized energy loss (viscous dissipation 2.69 W, pressure drop 3483 Pa).
• Demonstrated a 2.91 log-reduction in E. coli with negligible impact on milk's fat, protein, and lactose content.

Conclusions:

• The optimized Venturi reactor design effectively achieves non-thermal pasteurization of milk via hydrodynamic cavitation.
• This method ensures microbial safety without compromising the nutritional and sensory quality of milk.
• Hydrodynamic cavitation in optimized Venturi tubes is a viable and efficient alternative to conventional heat pasteurization for the food industry.