Enhancing heating uniformity in microwave pasteurization through eccentric rotation and bubbling: method and applications.

Microwave technology, with its advantage of rapid heating, offers a promising alternative to traditional heat pasteurization methods. However, its industrial application is constrained by inherent heating non-uniformity, especially evident in high-viscosity foods. Therefore, improving heating uniformity is crucial for enhancing the efficacy and efficiency of microwave pasteurization. In this study, Escherichia coli was used as the indicator microorganism to quantitatively assess the unevenness of heating in a small-scale single-mode microwave system. To enhance the uniformity of the thermal field, a combined perturbation strategy of eccentric rotation and bubbling was proposed. The optimal uniformity parameters suitable for viscosity ranges of 1-1500 mPa·s were identified. Experimental results demonstrated that the eccentric rotation-bubbling-assisted microwave treatment (MRW-UH) significantly improved the heat uniformity in foods of varying viscosities. Validation in representative food systems, including raw milk, blueberry jam, and sesame paste, further confirmed that MRW-UH exhibited superior stability in microbial control during storage when compared to conventional microwave heating and conductive heating. Additionally, MRW-UH more effectively preserved key quality attributes such as pH, titratable acidity, alkaline phosphatase activity, antioxidant capacity, and color. In summary, this study established a microwave pasteurization method based on eccentric rotation and bubbling perturbation, providing a feasible technical approach for uniform, efficient, and quality-preserving microwave pasteurization in foods of varying viscosities.