Experimental Study On Drying Quality Of Fruit And Vegetable

Drying technology is one of the most basic methods for fruit and vegetable processing.With the improvement of the life quality of consumers,the consumers requirements for dried fruits and vegetables is becoming more and more higher.In order to maximize the retention of color,vitamins and other nutrients of fruits and vegetables,maintain the appearance characteristics of fruits and vegetables,meet the demand of consumer,a variety of fresh fruits and vegetables as raw materials is used for drying experiments in this thesis,and the hot air drying,vacuum drying,hot air-vacuum combined drying and freeze(vacuum)-hot air combined drying are carried out to investigate the effects of different drying methods on drying quality of fruits and vegetables,so as to provide the theory and theoretical basis for the study of drying processes of fruits and vegetables.The experimental results of banana slices under four different drying technology are analyzed through the Excel,Matlab,Origin,and Design-Expert software respectively,and the effects of different drying technology on the drying time(drying rate),rehydration ratio,VC content and shrinkage are investigated in this thesis.The impact of slice thickness,hot-air temperature on the quality of dried banana slices under hot-air drying technology is studied.By the combined way of comprehensive score and comprehensive balance,drying time and other three drying quality evaluation indices are analyzed.The optimum conditions of hot air drying for banana slices is slice thickness 5mm,the hot air temperature 80 ℃.Vacuum drying and hot-air vacuum combined drying experiments adapt orthogonal experiment design method,and the analysis of range and variance is conducted by Matlab software to obtain the influential order of experimental factors on the drying quality and the optimum drying parameters for banana slices.The response surface analysis of common rotary combination design of freeze(vacuum)-hot air combined drying is conducted by the Design-Expert 8.0 software,and the regression equation between the experimental factors and comprehensive score of banana drying quality isobtained for analyzing the interaction effect among these experimental factors.Finally,by comparison,it is concluded that the drying quality of banana slices is the best under the combination of vacuum and hot air drying.The experimental results of bitter gourd slices under four different drying technology are analyzed through the Excel,SPSS,Origin,and Design-Expert software respectively,and the effects of different drying technology on the comprehensive drying quality of bitter gourd slices are investigated.The impact of slice thickness,hot-air temperature on the quality of dried bitter gourd slices under hot-air drying technology is studied.By the combined way of comprehensive score and comprehensive balance,drying time and other three drying quality evaluation indices for bitter gourd slices are analyzed.The optimum condition of hot air drying for bitter gourd slices is slice thickness 4mm,the hot air temperature 67℃.The vacuum drying experiments are designed by the orthogonal test design,and the SPSS22.0 software is used to analyze the range and variance of the obtained experimental data for obtaining the influential order of experimental factors on the drying quality and the optimum drying parameters for bitter gourd slices.The response surfaces analysis for analyzing the influence of the experimental factors on drying time and drying quality comprehensive value at hot-air vacuum combined drying test and freeze hot-air combined drying test are conducted by Design-Expert 8.0 software,and response surface method is used to analyze the experimental factors and drying time and drying quality between the values,and the regression mathematical model of combined drying is established.Finally,by comparison,it is concluded that the drying quality of bitter gourd slices is the best under the freeze hot-air combined drying technology.Due to the heat and mass transfer during the drying process of fruit and vegetable drying is complicated,it is very important to establish a reasonable mathematical model to study the drying mechanism,process optimization and automatic control of fruits and vegetables.In this thesis,through a lot of experimental data,the fitting analysis of six kinds of fruit and vegetable drying thin layer mathematical models established by domestic and foreign scholars are conducted,then a good mathematical model to describe and predict the drying process of fruits and vegetables is established.