Study Of Chestnut Defect Detection And Storage Characteristics Based On X-ray Imaging Technology

Chestnut is an important economic tree species in China,and its fruit is fresh and sweet,rich in protein,carbohydrates,fat,vitamins and other nutrients.However,the water content of chestnuts after harvesting is very high and the respiration is vigorous,and their quality is easily affected by the storage conditions.For example,uncomfortable temperature or humidity conditions can lead to internal defects such as mold,insect infestation and calcification of chestnuts,and these defects cannot be observed externally.The traditional damage observation method can only be assessed by sampling,which can result in wasted samples and is highly subjective.Commercial screening methods for substandard chestnuts are mainly flotation methods,which not only have low reliability,but also tend to increase the risk of chestnut spoilage in humid environments.In this paper,we investigate the detection of chestnut defects and storage characteristics using X-ray imaging technology as follows:1.Using the principle and characteristics of X-ray digital imaging system,the internal quality of chestnut is non-destructively discerned according to the internal quality difference and the law of ray attenuation.The optimal parameters for scanning chestnuts with X-ray imaging equipment were determined and the original images were acquired,and then the X-ray images were pre-processed by removing background interference from the images,enhancing internal features and image segmentation.It was observed that the defective features inside the chestnut would affect the Xray imaging effect,and the grayscale analysis of the radiographic image concluded that the worse the quality of the chestnut,the lower the overall grayscale of the radiographic image.Finally,by searching for local minima in the image,the defects in the chestnuts can be successfully found,thus screening out some of the unhealthy chestnuts.2.Due to the limitations of X-ray digital imaging,which is only suitable for roughly determining the internal quality of chestnuts,X-ray computed tomography(CT)technology is proposed to accurately analyze and discriminate the quality of chestnuts.The image processing software was used to calculate the body gray parameters and porosity of the chestnut CT images,and thus 47 chestnuts with severe defects were distinguished from268 validation sets with an accuracy of 93.7%.By comparing the CT images with slices of chestnuts,it was determined that the grayscale values of normal tissues ranged from 600 to 1200,and outside this range belonged to high grayscale calcified tissues with low grayscale worm holes,mold spots,cavities,or inner skin.Based on the morphological differences of the lowgray defects,the anisotropy and sphericity of each characteristic morphology were calculated to further differentiate them,and finally 85 lightly defective chestnuts were found,with an accuracy of 83.6%.3.To investigate the effects of differences in chestnut quality and storage conditions on the quality of chestnuts after harvesting,the weight loss,moisture content and polysaccharide content of "Qianxi" and "Luotian" chestnuts were measured under three common storage conditions(room temperature,refrigerated and frozen).It was found that the porosity of CT images correlated with the weight loss of chestnuts,and the moisture content had more influence on the grayness of CT images than the polysaccharide content.Under ambient storage environment,the first 5 weeks were the peak period for chestnut mold and insect disease development,while the quality of chestnuts under refrigerated and frozen storage conditions was always more stable.