Xie Yitong, Jin Xin, Bi Jinfeng
Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences (CAAS) / Key Laboratory of Agro-Products Processing, Ministry of Agriculture and Rural Affairs, Beijing 100193, PR China; College of Food Science, Shenyang Agricultural University, Shenyang 110866, China.
Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences (CAAS) / Key Laboratory of Agro-Products Processing, Ministry of Agriculture and Rural Affairs, Beijing 100193, PR China.
Food Res Int. 2025 Nov;219:116989. doi: 10.1016/j.foodres.2025.116989. Epub 2025 Jul 5.
While restructuring agricultural products enhances heat and mass transfer during freeze-drying, the underlying mechanisms remain poorly understood. This study employed a multiscale approach, combining freezing dynamics, sublimation drying kinetics, X-ray tomography, gas permeability assessments, thermodynamic parameters analysis, and mathematical modeling to systematically investigate the differences in transfer properties between natural and restructured peaches across the freezing and sublimation drying processes. Key results demonstrated that restructuring decreased the freezing time by 21.30 min-26.70 min and the sublimation time by 24 h-32 h, achieving an overall time reduction of 25.27 %-33.73 % compared to natural peaches. Microstructural analysis showed that restructuring significantly modified pore architecture, resulting in increased average pore size, overall porosity, open porosity, pore connectivity, specific surface area, and gas permeability, while simultaneously reducing closed porosity and relative apparent density. Thermodynamic characterization further revealed that restructuring not only reduced the heat capacity but also enhanced the thermal conductivity of peaches across the freezing and sublimation drying stages. The developed model successfully predicted experimental parameters and provided visualizations of the temporal evolution of the solidification and sublimation fronts, along with vapor velocity, temperature, and pressure distributions. Particularly noteworthy was the observation that restructured peaches exhibited lower pressure at the interface and accelerated movement of the sublimation front during the sublimation stage. These findings collectively demonstrate that restructuring significantly improved the heat and mass transfer characteristics of peaches during freezing and sublimation, enabling a more energy-efficient and environmentally friendly freeze-drying process with promising industrial applications.
虽然对农产品进行重组可增强冷冻干燥过程中的传热传质，但其中的潜在机制仍知之甚少。本研究采用多尺度方法，结合冷冻动力学、升华干燥动力学、X射线断层扫描、气体渗透性评估、热力学参数分析和数学建模，系统地研究了天然桃和重组桃在冷冻和升华干燥过程中传质特性的差异。关键结果表明，与天然桃相比，重组使冷冻时间缩短了21.30分钟至26.70分钟，升华时间缩短了24小时至32小时，总时间减少了25.27%至33.73%。微观结构分析表明，重组显著改变了孔隙结构，导致平均孔径、总孔隙率、开孔孔隙率、孔隙连通性、比表面积和气体渗透性增加，同时降低了闭孔孔隙率和相对表观密度。热力学表征进一步表明，重组不仅降低了桃在冷冻和升华干燥阶段的热容，还提高了其热导率。所建立的模型成功地预测了实验参数，并提供了凝固和升华前沿随时间演变的可视化结果，以及蒸汽速度、温度和压力分布。特别值得注意的是，观察到重组桃在升华阶段界面处的压力较低，升华前沿移动加快。这些发现共同表明，重组显著改善了桃在冷冻和升华过程中的传热传质特性，实现了更节能、更环保的冷冻干燥过程，具有广阔的工业应用前景。
