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

In this work,the principle and dynamic of superheated steam puffing fruit and vegetable were analyzed,the mathematical models of the core temperature of fruit and vegetable and the quality of water condensation which were changing with heating transfer time were established and the model to show puffing dynamic was set up by using green apple as thin layer material.The effects of superheated steam temperature,pressure and the moisture content of preliminary drying on the models were investigated as well.Hopefully,it would provide theoretical guidance for the development of a new type technology and process of superheated steam puffing fruit and vegetable and provide theoretical basis for puffing equipment research.The main conclusions could be summarized as follows:1.The mathematical model of the core temperature of fruit and vegetable which were changing with heating transfer time was established by using the principle of the transient heat conduction in heat transfer.The model expressed:(?).It could accurately predict the core temperature of fruit and vegetable changing with heating transfer time under different superheated steam temperature and the moisture content of preliminary.All of the determination coefficients(R2)reached more than 0.98.2.The mathematical model of the quality of water condensation changing with heating transfer time was established by using the law of the conservation of energy on the basis of the core temperature model.The model expressed:(?).It couid accurate predict the quality of water condensation changing with heating transfer time under different superheated steam temperature,pressure and the moisture content of preliminary.All of the determination coefficient(R2)reached more than 0.97.3.By the quantitative analyzing to the dynamic of superheated steam puffing with engineering thermodynamics and calculus,the mathematical model of the dynamic of superheated steam puffing fruit and vegetable was established.The model expressed:(?).It could accurated reflect the contribution of superheated liquid and superheated steam during puffing and predict expansion ratio of material under different superheated steam temperature,pressure and the moisture content of preliminary.All of the determination coefficient(R2)reached more than 0.99.? While superheated steam temperature were in the range of 430K?470K,the higher the temperature,the slowly bigger the expansion ratio.It indicated that the work of superheated liquid had a dominant position during superheated steam puffing fruit and vegetable.? While superheated steam pressure were in the range of 0.1MPa?0.5MPa,the higher the pressure,the significantly bigger the expansion ratio.It indicated that the pressure was an important factor to determine the puffing of fruit and vegetable.? While the moisture content of preliminary were in the range of 15%?35%,the higher the moisture content,the bigger the expansion ratio.It indicted futher that the work of superheated liquid had more bigger contribution than the work of superheated steam during the puffing of fruit and vegetable.