Dielectric and thermal mixture equations optimization for ready-to-eat particle foods during radio frequency thawing and reheating simulation

Particle materials with different shapes (ellipsoidal, spherical, and cubic) exhibit distinct void structures and spatial distributions of air gaps under stacking conditions, posing challenges in estimating suitable dielectric properties (DPs) and thermal properties (TPs) mixture equations during simulated radio frequency (RF) thawing and reheating. This study proposed a systematic strategy to identify optimal mixture equations for three components of ready-to-eat mixed fried rice: fried rice, green pea, and sausage. Actual DPs and TPs were measured, and a 27.12 MHz, 50 Ω RF heating model was established and experimentally validated. Subsequently, nine effective DPs and TPs schemes (combined 3 DPs with 3 TPs equations) were derived based on air volume fractions and widely adopted mixture equations. By comparing temperature distribution discrepancies after RF thawing and reheating, the most suitable equation combinations were identified: Landau and Lifshitz, Looyenga equation (LLLE) coupled with Maxwell-Eucken for fried rice, Bottcher equation (BE) coupled with Maxwell-Eucken for green pea, and LLLE coupled with Kopelman for sausage. Further validation under varying system conditions and time nodes confirmed the high reliability of these identified schemes, yielding the root mean square relative error of λ ( RMSRE λ ) below 0.06. Consequently, this study may provide a systematic method for analyzing mixture equations of particle materials during RF treatment, offering a reliable modeling foundation for future research on heating performance improvement. 1. A systematic strategy was proposed to identify suitable DPs and TPs mixture equations for particle foods. 2. Simulation models for RF treatment of fried rice, green pea, and sausage were established and validated. 3. Optimal DPs and TPs equation combinations for three particle samples with different shapes were determined. 4. Identified equation schemes demonstrated high reliability under varied system conditions and time nodes.