[Smart Farmers] How to check if fruits are "injured"? Fruit "Doctor" is now online!

In modern agriculture and food production, ensuring the quality and safety of fruits and vegetables is a vital task. However, internal quality problems of fruits and vegetables are usually difficult to detect, which poses a challenge to producers, retailers and consumers. Fortunately, modern technology has brought an impressive solution, namely near-infrared (NIR) transmission spectroscopy technology. This advanced technology allows us to gain an in-depth understanding of the internal conditions of fruits and vegetables, so that internal defects, rot, pests and nutrients can be detected quickly and accurately. At present, internal defect detection of fruits and vegetables has been widely used in the production and sale of agricultural products.

In the production of agricultural products, pests inside fruits and vegetables are an important issue for agricultural product quality. When detecting pests, NIR transmission spectroscopy technology can identify and determine whether there are pests and diseases inside fruits and vegetables by analyzing transmission spectral data, and conduct quantitative assessments. The same is true for hollowing problems. When detecting the degree of decay inside fruits and vegetables, NIR transmission spectroscopy technology can penetrate the skin of fruits and vegetables, identify the rotten areas inside fruits and vegetables, and quantitatively assess the degree of decay. This can help agricultural product producers and retailers screen out rotten fruits and vegetables in advance to ensure product quality and extend shelf life.

Taking apples as an example, apple core rot and water core disease are two common internal defect diseases, which are very important in apple quality assessment and export quality inspection.

Moldy core disease is an internal disease of apples caused by mold. It usually appears during the storage of the fruit and is often manifested as an imbalance in water potential, resulting in the formation of brown or black mold spots inside the fruit. Moldy core disease is usually detected through visual inspection and fruit cutting. If the fruit shows suspicious signs of lesions, it will be judged to be infected with moldy core disease. In recent years, some new non-destructive detection methods have also been studied for the detection of moldy core disease, including the use of NIR transmission spectroscopy technology, which analyzes the spectral information inside the fruit to detect and predict potential molten core disease lesions in apples, greatly reducing fruit loss and economic losses.

Apple "candy heart" is also a kind of apple disease, namely water core disease. It often occurs in the arid areas of the northwest plateau of China and is a physiological disease. When the diseased fruit is cut open, the intercellular spaces of its internal tissues are filled with cell fluid and appear water-soaked in the center of the fruit. Some also occur around the vascular bundles of the fruit and other parts of the flesh. "Candy heart" usually refers to Fuji apples with obvious water core disease. The water-soaked fruit core formed by the internal disease is often used by merchants as a selling point for publicity.

Apples with water core disease are edible until the water core inside the fruit turns brown and rots. At this time, the apples are rich in water, crisp and juicy, and have a high sugar content, which can satisfy some consumers' pursuit of sweetness. However, it should be noted that although apples with water core disease are edible, their shelf life is relatively short due to the impact of water core disease on the storage of the fruit. Because water core disease causes an increase in the cell sap inside the fruit, this may reduce the storage life of the fruit. Fruits with water core disease are more likely to soften, brown and rot during storage.

At present, water core disease detection mainly relies on visual observation and cutting the fruit for inspection. Water core disease causes the intercellular spaces inside the fruit to be filled with cell fluid, changing the optical properties of the fruit. Near-infrared transmission spectroscopy can detect this optical change and determine the extent and location of water core disease by analyzing the spectral data. Using near-infrared transmission spectroscopy technology to detect water core disease can not only improve detection efficiency and reduce the subjectivity of manual judgment, but also achieve rapid detection of large batches of samples.

In addition to defects, NIR transmission spectroscopy technology can also be used to detect the nutritional components inside fruits and vegetables. By analyzing the transmission spectrum data, the nutritional content inside fruits and vegetables, such as sugar, acidity, vitamin content, etc., can be obtained. This is of great significance for improving the edible value and market competitiveness of products, and optimizing the quality and production process of agricultural products. In addition, NIR transmission spectroscopy technology can also quickly measure the transmission spectrum of fruit and vegetable samples, and by establishing a mathematical model related to defects, it can realize the rapid screening and grading of internal defects in fruits and vegetables. This can improve production efficiency, reduce the cost of manual inspection, and ensure that the fruits and vegetables sold meet quality standards.

In the process of continuous innovation and development, the application of near-infrared (NIR) transmission spectroscopy technology has become a revolutionary technology in the field of modern agriculture and food production. It not only makes the detection of internal quality problems of fruits and vegetables more accurate and efficient, but also effectively improves product quality and competitiveness, and enhances the traceability and management efficiency of the fruit and vegetable industry.

Produced by: Popular Science in China to Benefit Farmers

Scientific Advisor: Guo Zhiming (Professor, School of Food and Bioengineering, Jiangsu University)

Co-ordinators: Liao Danfeng, Zheng Fengmao, Wang Changhai, Zhang Ruijie

Planning: Wu Yuetong

Editor: Wang Yuanyuan (internship)