Comparative study between conventional and microwave‐assisted pasteurization of packaged milk by finite element modeling

In this study, a comprehensive computer simulation model was developed to evaluate and compare temperature distribution, flow pattern, slowest heating zone (SHZ) location, and processing time in prepackaged milk during microwave-assisted pasteurization (MWP) and conventional pasteurization (CNP). Temperatures predicted by simulations were successfully validated against experimental data. C value, color, and thiamine kinetics coupled to temperatures predicted by simulation model were used to assess the impact of the process on product quality. Considering an equivalent microbial safety between both processes, MWP achieves a more uniform heating and, consequently, reductions of 28.6% in processing time and 14.8% in overall quality losses. Color changes were 35.5% and 37.0% for MWP and CNP, respectively; while thiamine losses were lower than 1% in both cases. Additionally, container orientation was evaluated for MWP, showing that horizontal orientation provided better temperature distribution and reduced quality losses. Practical applications Pasteurization has to ensure the prolongation of food lifetime, while the quality of product should be preserved. Minimizing the quality losses and at the same time for providing an adequate process with a desired sterility is one of the challenges to canning industry. In this sense, MWP provides an alternative to reduce damages to food quality in comparison with traditional treatment. Volumetric heating of microwave, can be extremely beneficial for liquids, such as milk, solving the fouling problem of heat transfer surfaces existing in conventional process. This study found that MWP and the horizontal position could be considered alternatives of processing to reduce the severity of the thermal treatment of milk and hence obtain a product of higher quality. This batch pasteurization using microwaves can represent a technological advance to apply by small dairy producers in rural areas, with possibility to be scaled up it to a higher production level.