基于MRI和CFD的快速烹饪过程猪肉中水分迁移规律研究

Based on the study of the optimization of moisture in the cooking process, we found that the law of moisture change obviously does not meet the first-order kinetic equation, so it cannot be optimized by adopting the dynamics of quality change. At present, the most feasible method is to obtain the whole temperature history and moisture change law of the food materials which is thought as particles through numerical simulation of heat/mass transfer processing, and optimize the process according to the simulation results. Our research team has constructed a heat/mass transfer model applied in the cooking process. Although this model can accurately simulate the temperature history, there is a big gap between the prediction of the water change and the measured value, especially it is difficult to achieve simultaneous accurate simulation of temperature and moisture changes law. The law of moisture change and its influencing factors in cooking process are the problems that must be solved in the optimization of cooking process. The reasons for the lack of the model have been initially analyzed. Based on this, the heat/mass transfer model is updating, and Low Field NMR Technology and MRI technology are used to obtain the spatial distribution of moisture and verify the reliability of moisture prediction more accurately. At the same time, according to the principle of water distribution, with the objective function of the optimal moisture content and the optimal model with the maturity value as the limiting function, the solution method of the control equation will be established, and the search for the optimal operating conditions is calculated to construct a universal cooking moisture transfer model. Finally, these studies in conjunction with the extension of numerical simulation technology, contribute to a more comprehensive reveal the inherent law culinary science.

基于前期开展烹饪过程中水分优化研究，发现水分变化规律明显不符合一级动力学方程，故无法采取品质变化动力学进行优化。目前，可行的手段中最优为通过热/质传递进行数值模拟获得烹饪原料颗粒的全局温度历史和水分变化规律后，依据模拟结果进行工艺优化。申请人课题团队已构建了烹饪过程中热/质传递模型，此模型虽然能够准确地模拟温度历史，但对水分变化的预测与实测值差距较大，尤其是难以达到同时准确模拟温度和水分变化规律。而烹饪过程中的水分变化规律及其影响因素，是烹饪工艺优化必须解决的问题。已初步分析模型不足的原因基于此，完善热/质传递模型，积累模型关键参数，利用低核磁共振及其成像技术，拿到水分空间分布，验证模型可靠性。后期，以水分含量最优为目标函数，以成熟值指标为限制函数的优化模型，建立控制方程的求解方法，计算搜索最优操作条件。最后，通过上述研究结合数值模拟技术的延伸应用，有助于更全面的揭示烹饪科学的内在规律。

中国居民饮食摄入的主要形式是烹饪食品。而烹饪自动化是社会发展的必然，有巨大经济潜力。两者都迫切需要关于烹饪品质形成与控制的基础研究。因此，在参数确定及数学模型控制方程完善的基础上模拟得到颗粒食品中心温度变化和水分含量分布模拟值。利用热电偶实时测定采集油炒过程中颗粒食品中心温度曲线，利用MRI和MATLAB数学软件获取颗粒食品水分含量分布实测值，通过颗粒食品中心温度及水分含量分布的实测值与模拟值对比验证完善后的数学模型可靠性。并构建考虑原料收缩现象、水分蒸发现象、基于多相多孔介质理论的中式快速烹饪热/质传递数学模型，延长考虑原料收缩现象的热/质传递数学模型的最大模拟时长，以满足中式快速烹饪过程研究需求；使用MRI方法验证了模型水分分布模拟的准确性，获取爆炒过程中原料烹饪收缩时内部温度和水分全局变化规律。.项目主要研究内容：1）为证明所建油传热数学模型的准确性与适用性，本文以颗粒食品水分分布为模型验证指标，利用低场核磁共振成像软件及MATLAB软件构建了颗粒食品水分含量分布测定的试验方法，获得了猪里脊肉在油炒过程的水分含量分布实测值。2）构建了考虑蒸发、收缩现象的爆炒过程中热/质传递数学模型并进行验证。新构建数学模型包含3个控制方程、2个收缩方程、7个边界条件和8个初始条件，27个附加方程及48个相关参数，并确定了有限元分析软件COMSOL的求解方法。而且发现颗粒特征尺寸、能量传递速率和流体-颗粒的换热时间/接触面积对颗粒成熟时间和含水率等烹饪品质有极显著（P<0.01）影响；颗粒切割越细、预热油温越高、搅拌操作越剧烈，其内部升温更快，烹饪成熟所需时间更短，烹饪品质越好。.中式烹饪是中国十多亿国民的主要饮食形式，对中式烹饪开展系统、深入地研究，把握烹饪过程传热与品质变化的内在原理，以推进烹饪科学的进步及烹饪的自动化、标准化，有助于揭示烹饪科学的内在规律，利于中式烹饪的对外宣传和推广。..