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Han Donghai: use spectral technology to do "physical examination" for fruits

"it is as simple as passing the security inspection system. During the transportation of apple, the volume, density and other data are detected, which is very time-saving and suitable for assembly line operation." A research group led by Professor Han Donghai of China Agricultural University has made an interesting research in recent years, which is very close to the market demand

this rapid nondestructive testing technology of fruit quality has brought a little new idea to the boring basic research. This project was supported by the National Natural Science Foundation of China in 2006. By means of visible/near-infrared spectroscopy and X-ray imaging technology, researchers conducted basic research on the application of information related to Apple internal and external quality testing, and set up a complete set of instruments and equipment in the process of research and development

the idea of using visible/near-infrared spectroscopy and X-ray imaging technology for fruit detection has been abroad. This time, researchers such as Han Donghai have taken some improvement measures, especially adding the exploratory research of using transmission and diffuse reflection technology to detect apple water heart disease and sugar content at the same time. The results show that this new technology has good effects, and its bright spot is that it has a bright application prospect, provides a theoretical basis for Apple postnatal sorting and storage, and is of great significance in reducing storage losses, ensuring product quality, and improving the added value of the castor plate of the curing box

China is the largest fruit producing country in the world, among which apple and Yali are the most important varieties, but the annual export volume is less, of which the export volume of Apple accounts for only 2.1% of the total output. An important reason that restricts the export of fruits in China is that the sorting and detection ability of fruits in China is weak, the speed is slow, the experimental environmental conditions are poor, and the sorting technology level cannot meet the requirements of the international market. At present, there are many regulations on the appearance quality of fruits in the standards of fruit sales quality in China. Next, I will introduce a simple and intuitive verification method of speed and force value of electronic tensile testing machine. Quality has only two indicators: hardness and soluble solids, while for those indicators that are invisible in appearance but significantly affect the internal quality of fruits, such as apple water heart disease, mold heart disease, internal browning and pear black heart disease, It has not been listed in the quality standard of fruit products. In order to strengthen the competitiveness of Chinese fruits in the international market and meet the quality classification requirements of exported fruits, the internal quality indicators of fruits must be included in the product quality standards. Detection of apple water heart disease and internal browning and detection of pear black heart disease are important indicators to reflect the internal quality of fruit products

because there is no difference in appearance between diseased fruits and normal fruits that produce apple water heart disease, internal browning and pear black heart disease, in the past, the inspection method of the internal quality of diseased fruits can only be carried out by observing the slices of random samples, but this method is a destructive sampling method, which is not only a great waste, but also meaningless to the classification of export products. Therefore, non-destructive and non-destructive testing methods must be used to evaluate and grade the internal quality of fruits in order to meet the requirements of the international market

fruit has certain optical properties, which are reflected by the radiation, transmission, absorption or scattering of multiple or single light based on ultraviolet (UV), visible light and near-infrared light (NIR) in the spectral range. The optical index of the internal quality of fruit is the representation of the correlation between the internal quality characteristics of fruit and the spectral response, which usually refers to pigments and chemical components. The research shows that the optical density of apples gradually decreases with the severity of water heart disease according to the transmission spectra of normal apples and water heart disease apples. According to the spectral energy difference of apples, the difference between water heart disease apples and normal apples can be seen intuitively. The exploratory study of simultaneous detection of apple water core disease and sugar content by transmission combined with diffuse transmission technology is more meaningful

the research of this research group involves the nondestructive measurement of Apple volume by X-ray image method, and the correlation coefficient between the calculated volume of the model and the real volume reaches 0.9203; The identification technology of visible/near-infrared energy spectrum of apple water heart disease and rot heart disease is the best. This cycle is composed of two isothermal processes and two adiabatic processes. The total discrimination rate of the model is 98.1%. The discrimination model is directly established by using energy spectrum to simplify data processing and improve speed. "X-ray can detect the internal density of fruit. Like the perspective principle of human body, the density of water center part and normal pulp part is different. X-ray imaging looks like a planar image, but it is actually a three-dimensional image, covering depth information." Han Donghai explained that the X-ray required for the test is very weak, the time is short, and the radiation level is lower than the international standard, so the fruit can be eaten safely

visible/near-infrared energy spectrum determines the internal information of fruit according to the feedback of light energy loss. This is like a group of deep sleeping molecules inside the fruit. After light energy penetrates into the fruit, the molecules absorb energy and wake up. 100% of the light energy enters, is absorbed by the molecules, and there will be loss after reflection. According to the loss, different internal mechanisms can be judged

the research group proposed that visible/near-infrared transmission spectroscopy has a good effect in detecting fruit lesions, while near-infrared diffuse reflectance technology has an advantage in detecting sugar content. Researchers use the ratio of the volume of the diseased part of the tested apple to the approximate volume of the complete apple as the honey fruit honey index, divide the range value of the honey index, and determine the honey fruit level of the tested Apple according to the range value of the honey index. This method can fill the gap of non-invasive grading honey fruit in China

"Now we have a new idea to develop a portable instrument for near-infrared energy spectroscopy. Our idea is that we can carry it on our shoulders and track the 'health state' of underage fruits still on the trees. For example, when the picking season is approaching, we can detect it once a week, locate a certain number of fruit trees in the southeast, northwest and northwest of an area, establish a health card for them, and find which one in the detection If the fruit on the tree is too small or the sugar content is low, we can consider taking measures such as supplementing nutrition to it alone. This will control the fruit quality in the growth process, reduce the risk of fruit farmers and reduce losses. " Han Donghai is full of confidence after confirming his research. He hopes that this technology can further meet the needs of social production

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