Page 39 - FoodFocusThailand No.245 September 2026

SMART
SMART PRODUCTION PRODUCTION

FASTER, BETTER, LEANER:

SCALING UP LIQUID PROCESSING WITH

CONTINUOUS MICROWAVE HEATING

The global food industry is seeking processing technologies that balance microbial safety with fresh-like
quality. High temperature short time (HTST) pasteurization using Plate Heat Exchangers (PHEs) is widely
used, but surface-to-center heat transfer creates temperature gradients, exposing the product near the heat-
transfer surface to excessive heat. This can cause protein denaturation, sugar degradation, and fouling,
reducing heat-transfer efficiency and increasing the need for Clean-In-Place (CIP) operations.

Microwave heating provides an alternative through Current State of Continuous Flow Microwave
volumetric heating, in which electromagnetic energy Heating
penetrates the product and generates heat throughout the CFMH is a promising technique because it enables volumetric
material rather than transferring heat from the surface inward. heating without an intermediate heat-transfer medium (Estel et
This enables rapid temperature elevation and can reduce al., 2017). In contrast, CFMH processing effectively distributes
the thermal gradients and localized overheating associated the generated heat, thereby diluting hot spots and reducing
with conventional conductive heating. the inherent risk of product overheating (Yang et al., 2023).
However, conventional microwave systems have been These advantages make CFMH highly suitable for various
limited by low energy efficiency and poor heating uniformity. industrial applications, offering enhanced safety, improved
Mechanical stirrers and turntables can improve field temperature control, and broader feasibility.
distribution but introduce moving components, maintenance Advances in computational power and algorithms
requirements, and equipment wear. Frequency modulation enable researchers to simulate the interaction between
can also improve heating uniformity but requires sophisticated electromagnetic fields, heat transfer, and fluid dynamics
and costly solid-state electronics. These limitations have for the development of CFMH. Multiphysics modelling
encouraged the development of Continuous-Flow can therefore be used to predict temperature distribution,
Microwave Heating (CFMH), which combines volumetric optimize applicator geometry, and evaluate operating
microwave heating with continuous processing that can parameters before experimental or industrial implementation
improve electromagnetic field distribution across a moving (Yang et al., 2023).
fluid stream (Guo et al., 2023). Nevertheless, several challenges remain. Limited
By combining the volumetric advantages of microwave microwave penetration depth and variations in material
energy with the high-throughput capabilities of a continuous- homogeneity can produce uneven electromagnetic energy
flow design, CFMH addresses the scalability challenge. It absorption, resulting in hot spots and potentially thermal
maintains a steady “cold spot” temperature for safety while runaway. Therefore, improving heating efficiency, temperature
avoiding boundary-layer overheating that affects PHEs, uniformity, and adaptability to different food matrices remains
offering a sustainable solution for liquid food processing. essential.

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