Study On The Method Of Measuring The Appearance Quality Of Fruit And Vegetable Materials During Drying

Fruits and vegetables are rich in nutrients such as vitamins,minerals and organic acids,which are essential for daily life.However,due to seasonality and perishability,fresh fruits and vegetables often have a high rate of loss,and the development of the fruit and vegetable processing industry can effectively alleviate this problem.Drying is an important method of processing fruits and vegetables.It has been widely used in the fruit and vegetable processing industry.The method generally inhibits the growth of microorganisms by reducing the moisture content of fruits and vegetables,and prolongs the shelf life of materials.But the browning reaction often occurs during the drying process,and in three-dimensional shape,shrinkage and crimp seriously affect the appearance quality of materials.Therefore,it is of great significance to study the method of detecting the appearance quality of fruit and vegetable materials during the drying process.This study designed a set of fruit and vegetable drying device and real-time color detection system,and proposed two new methods of three-dimensional shape detection in the drying process of fruits and vegetables.The specific research contents of the thesis are as follows:1.According to the preliminary exploration of the research on the drying of fruits and vegetables,the selection of components such as centrifugal fan,moisture exhaust fan,steam humidifier,electric heating piece and temperature and humidity controller was determined.A tunnel-type fruit and vegetable drying device was designed.The inside of the device was circulated by hot air circulation to reduce energy consumption and improve temperature and humidity control accuracy.By counting the control range of the controller under different temperature and humidity gradients,the temperature control effect is best when the temperature is low and humidity is high(50 °C,50% RH),and the control range can reach ±0.58 °C.When the temperature is high and humidity is low(80 °C,10% RH),the temperature control effect is the worst,and the control range is ±2.05 °C.When the temperature is high and humidity is low(80 °C,10% RH),the humidity control effect is the best,and the control range can reach ±2.96% RH.When the temperature is low and humidity is high(50 °C,50% RH),the humidity control effect is the worst,and the control range is ±5.11% RH.2.A set of color real-time detection system was designed.According to the test requirements,the selection of industrial cameras and lenses was determined,and the light source was determined to be a ring-shaped LED light source,and a double-diffuse transmission plate was used for lighting.In order to facilitate image acquisition,the color real-time detection software has been developed,including three functions of image online acquisition,processing and data storage,color correction uses a multiple regression method based on a standard 24-color card.In order to verify the feasibility of the color real-time detection system,the on-line test analysis was carried out with the flaky pleurotus eryngii as the test object.The test results show that the value of chromatism(35)E of the materials under different temperature and humidity conditions increases with the drying time.The higher the temperature or humidity,the higher the(35)E value at the end of drying,and the(35)E values of the drying end of the material at 50,60,70,80 °C are 2.09,3.26,5.93,8.15,respectively.The(35)E values of the material drying end points under 10,20,30,and 40% RH conditions were 1.72,4.49,5.69,and 8.90,respectively.3.A new method for detecting the shape of fruits and vegetables during drying.Use the Kinect V2 sensor to build an image acquisition platform to obtain the depth image and color image of the material,and extract the area of the material in the depth image according to the corresponding relationship between the two positions.Then through the image processing method to find the material projection area,depth mean and standard deviation and other parameters,and use this as characteristic parameters to reflect the morphological change of the material during drying.Experiments on potato flakes showed that low temperature(50 °C,60 °C)and high temperature(70 °C,80 °C)had significant effects on shrinkage and curling of potato flakes when dried(P<0.05).The higher the temperature,the greater the shrinkage of the potato flakes.The drying temperature and the degree of curling of the potato chips increased first and then decreased.The curling degree was the highest at 60 °C,and the average depth was 27.81 mm,which was reduced to 18.86 mm at 80 °C.The flatness of potato slices was significantly different at four temperatures(P<0.05).The standard deviation of potato chips at 49 °C was 7.99 mm,and it decreased to 5.71 mm at 80 °C,indicating that the flatness increased with drying temperature.High and increase.4.In order to further improve the detection accuracy,another method for detecting the shape of fruits and vegetables when drying is proposed.Use the Gocator3210 sensor to build a point cloud data acquisition platform to obtain the point cloud image of the material,remove the image background by cloth simulation filtering,remove the noise data by statistical filtering and radius filtering,and reconstruct the 3D surface model of the material using the greedy projection algorithm and the Laplace smoothing algorithm.The surface area and roughness of the material are calculated to reflect the three-dimensional shape change law,and the accuracy of the method is verified by the known surface verified by the vernier caliper.The test was carried out on the flaky pleurotus eryngii.The results showed that the surface area of pleurotus eryngii shrink at different temperature(50,60,70,80 °C)and humidity(10,20,30,40% RH).Both the shrinkage rate and the surface roughness increase with the drying time,and the higher the temperature and humidity,the more severe the deformation of the material,and the greater the shrinkage and roughness.