Study On Infrared Assisted Spouted Bed Combined Drying Of Fresh Peanut Fruits In Shell

Peanut is an annual edible herb of the Rosaceae family,which is rich in protein and oil,and also contains a variety of nutrients such as VB,VE,folic acid,calcium,phosphorus,iron,etc.,with extremely high edible value.Research shows that 4,700years ago,peanuts already existed in China,and now my country’s annual peanut output ranks first in the world.Due to the growth cycle of peanuts,they are mostly harvested in high temperature and rainy summer,and the moisture content after picking is high,and they are easily corrupted and deteriorated during transportation and storage,which seriously restricts the improvement of their economic benefits.Drying is an effective means to solve the above problems.However,traditional sun drying and conventional hot air drying are not only inefficient,but also cannot meet the effective retention of peanut nutrients and active substances.Far-infrared radiation has the advantages of good thermal effect and energy saving.The spouted bed can make the material do a fountain-type reciprocating motion in the bed,and realize the regular intermittent contact between the material and the hot air in the bed.This study combines the advantages of the two and complements each other.A new type of infrared-spouted bed drying equipment suitable for peanut materials was developed,and based on this platform,the combined drying characteristics of shelled fresh peanuts were characterized.The main research conclusions are as follows:(1).The drying quality indexes such as microstructure,hardness,porosity,amino acid and fatty acid of fresh peanut with shell under different drying conditions and their changing laws during the drying process were studied.In the fast drying stage,the drying rate increased gradually with the change of drying methods,and the drying rate of the infrared spouted bed drying was the highest.Through the observation of microstructure,the drying treatment deformed the structure of peanut shells and peanut kernels,and the porosity increased,and finally was stable,but the porosity of peanut shells still increased when the infrared-spouted bed drying reached the drying end point.Through the puncture test,it can be seen that the hardness of peanut kernels and peanut shells changes in the same trend under different drying methods.Through physical and chemical analysis,it was found that the content of amino acids and fatty acids in peanut kernels decreased significantly under the four drying methods(P<0.05),but the content of amino acids and fatty acids in fresh peanut with shell after drying by infrared-spouted bed was significantly higher.(2).The infrared-spouted bed drying characteristics of fresh peanut with shell were studied,and the optimal results of infrared-spouted bed for fresh peanut with shell were obtained by orthogonal experiments with energy consumption,acid value,total color difference and peroxide value as evaluation indicators.Operation process:The drying temperature and the inlet wind speed had a significant effect on the overall quality of fresh peanut with shell,but the quality of the excipients had little effect.The primary and secondary order of influence was drying temperature>inlet air velocity>excipients mass.The optimal process combination of infra-red-spouted bed drying for fresh peanut with shell was drying temperature of 70°C,inlet air velocity of 19 m/s and mass of excipients of 2 kg.The infrared spouted bed data were fitted by the common mathematical models in 7,and the Midilli model was obtained to describe the drying characteristics of fresh peanut with shells by infrared spouted beds,and it had a strong effect on infrared-spouted bed drying of fresh peanut with shells.(3).Through a large amount of experimental data,a BP neural network moisture content prediction model for the drying of shelled fresh peanut in an infrared spouted bed was established with the MATLAB software system as the platform.The model has been tested to have an excellent ability to predict the change of moisture content during IR-spouted bed drying of shell peanut.Compared with the selected mathematical model,under the given experimental conditions,the R~2 between the predicted value and the experimental value of the Midilli model is 0.9761,and the BP model is 0.9963.The prediction error values of these models differ by 9.79%.Therefore,the BP neural network model performs better.