Introduction
Fruits and vegetables are rich in vitamins and nutrients, and they play a crucial role in maintaining the daily nutritional intake of the human body [1]. However, fruits and vegetables are fresh foods. They are easily affected by external or internal factors during planting, harvesting, transportation, packaging, and storage, resulting in varying degrees of deterioration and disease in their quality. According to the report released by Chinese official institutions, the post-production loss rate of fruits and vegetables in China is 15–20% and 20–25%, respectively, much higher than the developed countries average level. Furthermore, approximately 200 million tons of fruits and vegetables are lost annually during transportation. The spoilage and decay of these products could provide essential nutritional requirements for close to 200 million individuals but instead result in economic losses of 75 billion yuan [2,3]. In addition, the overuse of pesticides by producers to enhance crop production results in residual pesticides in fruits and vegetables, which pose a significant risk to human health, potentially leading to poisoning and various diseases [4,5,6]. Therefore, developing a rapid, highly accurate, non-destructive fruit and vegetable quality and safety testing technology is highly significant from a practical standpoint. The conventional techniques of assessing the quality of fruits and vegetables mainly rely on sensory evaluation and chemical analysis. However, these methods are vulnerable to interference, exhibit low accuracy, slow detection speed, and require high resource consumption. Therefore, researchers worldwide have continuously explored and developed intelligent non-destructive detection technologies, including Raman spectroscopy, near-infrared spectroscopy, RGB vision detection, electronic nose, acoustic characteristics, dielectric properties, and other emerging nondestructive testing technology [7].
Nondestructive testing technologies commonly used today have their advantages. Near-infrared spectroscopy inspection technology analyzes different spectral features of fruits and vegetables within the near-infrared spectrum. Due to its strong penetrating power, it is primarily employed for evaluating the internal quality of fruits and vegetables. RGB vision detection technology analyzes fruits and vegetables based on their image information, offering high efficiency, automation, and other advantages. It is primarily utilized for the inspection of fruit and vegetable appearance. Electronic nose technology, which simulates the olfactory system of animals, can analyze the odor emitted by fruits and vegetables to distinguish their varieties and quality, with the advantages of rapid detection, high precision, non-destructive, etc., mainly for testing the freshness, maturity, and varieties of fruits and vegetables. Acoustic characteristics technology can be utilized to assess the ripeness, freshness, and overall quality of fruits and vegetables by analyzing their acoustic signals. Dielectric property technology is a non-destructive, fast, and efficient method that measures the dielectric properties of fruits and vegetables to assess their water content, hardness, and other important information.
Raman spectroscopy is a detection technique that utilizes the frequency shift and intensity changes of scattered light when a sample interacts with a laser light source, which allows for the acquisition of molecular vibrational information and enables the analysis and identification of the chemical composition, structure, and properties of the sample. Apart from the common advantages of high efficiency and non-destructive properties, Raman spectroscopy is not interfered with by water. It can be detected through the aqueous solution. Raman spectroscopy detects various types and indexes of fruits and vegetables and is suitable for internal and external quality inspection. Due to its high sensitivity and molecular specificity, this technique excels in detecting trace components often missed by other non-destructive testing methods. By analyzing the characteristic vibration frequency of molecules, it can quickly evaluate the quality and nutritional composition of fruits and vegetables while detecting material composition and structure [8]. Furthermore, this technology can detect hazardous substances and surface pesticide residues in fruits and vegetables. Given its potential for development and application, it is a promising solution for assessing fruit and vegetable quality and safety.
This study elaborates on five types of Raman spectroscopy technologies. It summarizes the current research on applying Raman technology for detecting fruit and vegetable quality and safety, mainly including variety classification, qualitative and quantitative quality analysis, spoilage bacteria leaching, drug residue detection, etc. Furthermore, this study discusses the current difficulties in technology, and practical application of Raman technology, and the development trend of its outlook for the future.
References
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Journal: Horticulturae Authors: Xu et al
Introduction Fruits and vegetables are rich in vitamins and nutrients, and they play a crucial role in maintaining the daily nutritional intake of the human body [1]. However, fruits and vegetables are fresh foods. They are easily affected by external or internal factors during planting, harvesting, transportation, packaging, and storage, resulting in varying degrees of deterioration and disease in their quality. According to the report released by Chinese official institutions, the post-production loss rate of fruits and vegetables in China is 15–20% and 20–25%, respectively, much higher than the developed countries average level. Furthermore, approximately 200 million tons of fruits and vegetables are lost annually during transportation. The spoilage and decay of these products could provide essential nutritional requirements for close to 200 million individuals but instead result in economic losses of 75 billion yuan [2,3]. In addition, the overuse of pesticides by producers to enhance crop production results in residual pesticides in fruits and vegetables, which pose a significant risk to human health, potentially leading to poisoning and various diseases [4,5,6]. Therefore, developing a rapid, highly accurate, non-destructive fruit and vegetable quality and safety testing technology is highly significant from a practical standpoint. The conventional techniques of assessing the quality of fruits and vegetables mainly rely on sensory evaluation and chemical analysis. However, these methods are vulnerable to interference, exhibit low accuracy, slow detection speed, and require high resource consumption. Therefore, researchers worldwide have continuously explored and developed intelligent non-destructive detection technologies, including Raman spectroscopy, near-infrared spectroscopy, RGB vision detection, electronic nose, acoustic characteristics, dielectric properties, and other emerging nondestructive testing technology [7]. Nondestructive testing technologies commonly used today have their advantages. Near-infrared spectroscopy inspection technology analyzes different spectral features of fruits and vegetables within the near-infrared spectrum. Due to its strong penetrating power, it is primarily employed for evaluating the internal quality of fruits and vegetables. RGB vision detection technology analyzes fruits and vegetables based on their image information, offering high efficiency, automation, and other advantages. It is primarily utilized for the inspection of fruit and vegetable appearance. Electronic nose technology, which simulates the olfactory system of animals, can analyze the odor emitted by fruits and vegetables to distinguish their varieties and quality, with the advantages of rapid detection, high precision, non-destructive, etc., mainly for testing the freshness, maturity, and varieties of fruits and vegetables. Acoustic characteristics technology can be utilized to assess the ripeness, freshness, and overall quality of fruits and vegetables by analyzing their acoustic signals. Dielectric property technology is a non-destructive, fast, and efficient method that measures the dielectric properties of fruits and vegetables to assess their water content, hardness, and other important information. Raman spectroscopy is a detection technique that utilizes the frequency shift and intensity changes of scattered light when a sample interacts with a laser light source, which allows for the acquisition of molecular vibrational information and enables the analysis and identification of the chemical composition, structure, and properties of the sample. Apart from the common advantages of high efficiency and non-destructive properties, Raman spectroscopy is not interfered with by water. It can be detected through the aqueous solution. Raman spectroscopy detects various types and indexes of fruits and vegetables and is suitable for internal and external quality inspection. Due to its high sensitivity and molecular specificity, this technique excels in detecting trace components often missed by other non-destructive testing methods. By analyzing the characteristic vibration frequency of molecules, it can quickly evaluate the quality and nutritional composition of fruits and vegetables while detecting material composition and structure [8]. Furthermore, this technology can detect hazardous substances and surface pesticide residues in fruits and vegetables. Given its potential for development and application, it is a promising solution for assessing fruit and vegetable quality and safety. This study elaborates on five types of Raman spectroscopy technologies. It summarizes the current research on applying Raman technology for detecting fruit and vegetable quality and safety, mainly including variety classification, qualitative and quantitative quality analysis, spoilage bacteria leaching, drug residue detection, etc. Furthermore, this study discusses the current difficulties in technology, and practical application of Raman technology, and the development trend of its outlook for the future.
References