| The moisture content of the fresh Zanthoxylum bungeanum is almost 200%,and the quality can be easily influenced by water,temperature,light and oxygen,and which may cause huge waste.After being harvested,drying is an important process for the Zanthoxylum bungeanum,which has significant influences on transporting and storing.If the drying process is mishandled,it will cause serious damage to its quality and lead to the loss of nutrient,and even seriously reduce its economic benefit.What's more,the traditional methods of drying have disadvantages such as low efficiency and poor quality.Vacuum drying is a novel technology which combines virtues of high quality,energy conservation,protecting the environment and so on.Therefore,the vacuum drying will be adopted to the Zanthoxylum bungeanum on the following aspects:(1)The characteristic of vacuum drying of Zanthoxylum bungeanum were investigated in this part.The drying temperature(50?60?70?),vacuum degrees(-0.02?-0.04?-0.06Mpa)and the load of(30?40?50g)were selected to established the comprehensive test in order to analysis the dehydration characteristics under different drying conditions.By the seven traditional models were investigated on these evaluation index about R Square(R2),Residual Sum of Squares(SSE)and chi-square(?2),and experimental data were simulated.The results showed that the cubic model had a large decision coefficient and a small error value that much more adequate for describing the dehydration characteristics of the Zanthoxylum bungeanum.(2)The BP network was established for the vacuum drying of the Zanthoxylum bungeanum.Taking drying time,vacuum degree,temperature and load as the network input,and moisture as the output,the Matlab neural network tool box was selected trained 894 experimental data of 25 groups,and two groups data was fitted.The results showed that BP network has a great fitting degree,the average relative error E(%)are 8.698% and 6.593% respectively.The BP model can directly and accurately predict the moisture of the Zanthoxylum bungeanum.(3)Analysis of vacuum drying process and model establish of the Zanthoxylum bungeanum based on Weibull function.The Weibull function and its scale parameter ? and shape parameter ? were adopted to analysis the drying process and the model was established of vacuum drying of the Zanthoxylum bungeanum.The result showed that the Weibull function model has a high degree of fit for the vacuum drying of the Zanthoxylum bungeanum,the temperature is the main factor affecting the vacuum drying of the Zanthoxylum bungeanum.With the increase of temperature,the scale parameter ? of Weibull model decreases and the effective diffusion coefficient increased,indicated that drying rate increases,the drying time cut down.The shape parameter ? of Weibull function is greater than one indicated that the vacuum drying of the Zanthoxylum bungeanum has a significant acceleration phase.(4)Preliminary study quality on vacuum drying of the Zanthoxylum bungeanum by using chromatic aberration and aperture ratio.The result showed that with the increased of temperature the greater of the chromatic aberration.With the increasing of the temperature and vacuum degree,the greater of the aperture ratio.Therefore,the low temperature is used for drying the Zanthoxylum bungeanum to obtain the quality.(5)Optimization of vacuum drying technic of the Zanthoxylum bungeanum.Three factors and three index were selected to the ternary quadratic rotation combination experiments to optimize the drying technology.The Design-Expert 8.0 software and the response surface method were used to analysis the interactions that factors effect on index.The single-index analysis was carried out by the response surface method,and the weighted average method was used to determine the Zanthoxylum bungeanum vacuum dry the best process parameters was the temperatue of 62.18?,the vacuum degree was-0.054 Mpa,the load is 37.23 g.In this condition,the relative error of each index was less than 10%,had a highly reliable. |
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