Study On The Dynamic Mechanism Of Saturated Steam Puffing Fruit And Vegetable

In this study,the mechanism of saturated steam heating and puffing fruit and vegetable technology was analyzed,the mathematical models of the core temperature of fruit and vegetable and the quality of water condensation which were changing with heating time were established and the puffing model to show the dynamic relationship was set up by using Carrot for raw materials.The effects of moisture content of Carrot by predewatering and the temperature of saturated steam on the models were investigated as well.Hopefully,it would provide theory and technical support for production and the basis for equipment research.The following researches were obtained from this paper.1.The mathematical models of the core temperature of fruit and vegetable and the quality of water condensation which were changing with heating time were based on the contents of heat transfer theory,such as unsteady heat conduction and phase changed convection heat transfer.? The lumped-capacity method was not applicable to analyze the core temperature of fruit and vegetable and the quality of water condensation changing with heating time during saturated steam heating,namely the temperature gradient in the internal space of fruit and vegetable cannot be neglected.? The mathematical model of the core temperature of fruit and vegetable changing with heating time was established with an analytic approach to the unsteady heat conduction processes in one-dimensional.The model expressed:T=Tsat-(Tsat-Ts).P1exp(-?t/r02?12)(t?20s).It could accurately predict the core temperature of fruit and vegetable changing with heating time during different temperature of saturated steam heating different moisture content of fruit and vegetable,and all of the determination coefficients(R2)reached 0.97.While the moisture contents of fuit and vegetable were in the range of 20%? 32%,the higher the moisture content,the lower the model alignment.? The mathematical model of the quality of water condensation changing with heating time was established with the law of the conservation of energy.The model expressed:predict the quality of water condensation changing with heating time during different temperature of saturated steam heating different moisture content of fruit and vegetable,and all of the determination coefficients(R2)reached 0.95.2.The puffing model was established with engineering thermodynamics and elasticitymechanics.The model expressed:S=exp[989Wg+W1)/8K?r03].It could accurately predict expansion ratio during different temperature of saturated steam puffing different moisture content of fruit and vegetable,and all of the determination coefficients(R2)reached 0.95.I While the moisture contents of fruit and vegetable were in the range of 20%?32%,the higher the moisture content,the bigger the expansion ratio.It further indicated that the work of superheated liquid flash evaporation in the organization of fruit and vegetable had an important position during saturated steam puffing fruit and vegetable.II While the temperature of saturated steam were in the range of 390K ? 430K,the higher the temperature,the bigger the expansion ratio.It indicated that the temperature of saturated steam was more important key factors of the expansion ratio than the moisture content of fruit and vegetable.