烹饪过程动力学函数、优化模型及火候定义

    Kinetic functions, optimizing model and definition of "Huohou" for Chinese cooking

    • 摘要: 为揭示烹饪的内在技术原理,在烹饪过程原理之上开展了深入的动力学分析。由于烹饪的非稳态特性,可以用蒸煮值等动力学参数来描述烹饪过程的食品品质变化,并认为烹饪的技术关键是使原料在达到成熟的同时过热最小,由此提出和定义了新的动力学函数--成熟值和过热值,分析了不同空间位置的成熟值和过热值,均给出了数学表达式。同时建立了以过热值为目标函数、成熟值为约束函数、传热条件为优化变量的烹饪优化数学模型。得到烹饪的广义火候定义:烹饪过程中使菜肴品质达到最优的一切温度控制手段;以及动力学定义:在菜肴的蒸煮值达到成熟值的同时使得过热值最小的烹饪操作。分析表明,烹饪过程是由一系列控制方程和参数决定的,是有规律的、可控的。

       

      Abstract: As the most important technical term of traditional Chinese cuisine, "Huohou" originally means the degree of heating, and also implies the appropriate termination of cooking. There is not unanimous understanding of "Huohou" in the published literature; some of the existing concepts were mostly descriptive without theory support, and several of them contain conspicuous mistakes. In this thesis, as the third of a series of six theses, the author tried to define "Huohou" with quantitative equations on the bases of kinetics and heat transfer, and reveal the key principle of Chinese cooking technology. The quality factors of maturity for finished products in cuisine can be characterized by one or more indicators about flavor chemistry, pigment chemistry, texture, microbiology, toxicology, etc. Usually, the quality factors are merely for solid particles. Transient heat transfer is the basic characteristic of solid particles in cuisine, hence there are different temperature histories in different heat transfer characteristic dimensions of a particle; thus, the intraparticle quality distribution is brought about. Ordinarily, the last mature point is the coldest spot in the food system, which should be the center of particles in general. Along with the food center reaching maturity, the excentral part has already been overheated, particularly the surface, where quality deterioration is produced. Therefore, it was suggested that the goal of "Huohou" is to minimize quality degradation via overheating while food materials are heated to maturity. In order to express the degree of maturing quantitatively under variations of temperature, several novel kinetics functions are put forward for the cooking process, including maturity value (M value), maturity time tM and overheated value (O value). The maturity value was physically defined as the equivalent heating time to a reference temperature when cooking quality reaches maturity, and maturity value is the C value at maturity time. The overheated value was physically defined as the equivalent heating time that forms quality deterioration for relative reference temperature when cooking quality reaches the overall maturity. Maturity values and overheated values may appear in different spatial positions in the food system in cuisine, such as surface maturity value, volume average maturity value, surface overheated value and volume average overheated value. According to the experience of other thermal processes, like thermal sterilization, we extrapolated that there are the optimal conditions of heat transfer operating for cooking quality in thermal process of liquid-particles in traditional Chinese cuisine only if Z value of maturation quality factor and Z value of overheated quality factor are not the same. Based on the governing equations for heat and mass transport processes, an optimal model was constructed for mixture of liquid and particles in typical Chinese cuisine, which has a constraint condition as the C value equals maturity value; an objective condition to minimize the overheated value; and design variables including the parameters of heat transfer controlling, such as liquid temperature and the heating power. Thus, "Huohou" was synoptically defined as the cooking-temperature regimes that can enable cooking quality to achieve optimal, and it was dynamically defined as the cooking operation minimizing the overheated value while ensuring that the cooking value reaches maturity.

       

    /

    返回文章
    返回