Electrostatic storage and fresh-keeping technology

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Fruit and vegetable electrostatic storage and preservation technology

brief introduction: This paper describes the research status of bioelectromagnetic effect and fruit and vegetable electrostatic storage technology at home and abroad, and prospects the development and application of this technology

1 overview

fruits and vegetables are rich in nutrition and are indispensable food in people's life. It not only contains the necessary nutrients for the human body, but also the indispensable substances to resist diseases. According to statistics, the output of fruits alone was only 600 tons in 1975, 10 million tons in 1985, 18.3 million tons in 1990, and 30 million tons by 1993. However, due to the great geographical and climatic differences in China, the origin is extremely unbalanced, resulting in a passive situation of "rotten in the peak season, interrupted in the off-season, adjusted outward in the peak season, and asked for in the off-season". At the same time, due to the lack of effective storage methods and transportation equipment suitable for the current economic conditions, a large number of fruits and vegetables in the origin are concentrated, and a large part of them cannot be transported out in time, and quickly deteriorate soon after harvesting and concentration, The annual loss accounts for 30% - 40% of the total output. The deterioration of many fruits and vegetables is accompanied by the production of toxic factors, which not only deprives people of these fruits, but also causes considerable economic losses, pollutes the environment, and seriously frustrates farmers' planting enthusiasm. Post harvest loss of fruits and vegetables is a global problem, which has been widely concerned at home and abroad. On the other hand, the substantial increase in production of fruits and vegetables, the centralized marketing of products, and the changes in people's dietary concepts will inevitably put forward new requirements for the storage and preservation of fruits and vegetables. Therefore, the storage and fresh-keeping processing of fruits and vegetables has become one of the important research topics in the processing of contemporary agricultural products, and it is also a problem that needs to be deeply studied and solved for a long time in the future. Therefore, scholars all over the world are committed to looking for newer and more efficient storage and fresh-keeping technologies

2 research progress on electrostatic storage and fresh-keeping technology of fruits and vegetables

2 Since the 1950s, people have explored the storage of fruits and vegetables in two interrelated ways. By studying the physiological, biochemical and microbial processes of fruits and vegetables after harvest, some scholars tried to decipher the password of the activity mechanism of the universal mechanical experimental machine for teaching in Colleges and universities with the continuous increase of automobile production, so as to provide a reliable theoretical basis for the long-term storage and preservation of fruits and vegetables [1 ~ 3]; More scholars have gradually obtained some practical methods from a large number of storage practices, such as cold storage, frozen storage, controlled atmosphere (Ca and MA), physiologically active substance control, chemical coating and radiation storage. Summarizing their research results shows that the factors affecting the storage stability of fruits and vegetables mainly include: the type and quality of raw materials used, storage temperature, humidity, gas composition, available nutrients, the degree of microbial contamination, the use of growth inhibitors, as well as the type and mode of packaging, the degree of mechanical damage to packaged food in sales and storage, and so on

in practical application, these storage methods have obvious limitations. For example, the most widely used refrigeration and air conditioning technology has some problems, such as poor effect on some difficult to store fruits and vegetables with high water content, such as grass mold, peach, litchi and tomato, large investment, difficult maintenance, and high requirements for the quality of storage and the level of managers. Therefore, as far as these fruits and vegetables are concerned, these technologies can not achieve the expected storage effect. At the same time, because they are closely related to economic conditions and personnel quality, the possibility of practical application is small. That is why it promotes the development of new technologies with obvious fresh-keeping effect, less investment, less energy consumption, more common and practical characteristics

in recent years, some scholars have put forward a new concept of marginal scientific research means - micro energy technology from the field of food processing, combined with physics and physical chemistry, that is, to use weak energy such as electric field, magnetic field, electromagnetic wave, sound wave, pressure field to deal with food processing and other processes in an energy-saving, efficient and high-quality way. On this basis, other scholars [4] further combined fruit and vegetable storage physiology, biochemistry, cell physiology and other disciplines, made use of the "accumulation" effect of electromagnetic micro energy in organisms, and put forward new ideas for the storage and processing of agricultural products to achieve new and energy-saving. This trend not only opened up new fields of electromagnetic technology application, but also found new research means for bioengineering technology and agricultural product processing technology, The preliminary experimental results show that electromagnetic field has the possibility of long-term storage and preservation of fruits and vegetables. Therefore, electromagnetic P preservation technology in the new era is pregnant with great research and development prospects

the concept of micro energy technology comes from the basic research on electromagnetic field that people have already carried out [5]. They believe that all kinds of biological materials that make up organisms, from single cells and biomolecules, to the organism composed of tissues and organs in animal and plant tissues and organs, and even animal and plant objects are composed of charged particles, and all biological systems contain a common electromagnetic factor in the environment in which they live, and also exist in the complex self-regulation system of animals, Energy and information are transmitted through electrical signals at any time in it. Therefore, the existence and influence of external electromagnetic fields are likely to play an important role in the process of realizing various physiological adjustments and life behaviors. Therefore, studying and discussing the effect of external electromagnetic field on life and the response of animals and plants to the effect of external electromagnetic field, that is, the effect of bi2ology inductcd by external electromagnetics, has increasingly become the basis for promoting and developing electromagnetic preservation technology. The feasible method is: by studying the role of electromagnetic field in the fresh-keeping and storage of fruits and vegetables, as well as the regularity and possible mechanism of these roles, we can have a deeper understanding of the physiological metabolism of fruits and vegetables, and study and develop the storage of fruits and vegetables from the perspective of marginal science, combined with the special methods of micro energy utilization to achieve the purpose of energy-saving and efficient fresh-keeping and storage of fruits and vegetables

2. 2 research status of electrostatic storage of fruits and vegetables

preliminary research shows that electrostatic storage of fruits and vegetables is achieved by using negative high-voltage electrostatic field and biological negative effects. In recent years, a large number of experimental reports have shown the potential possibility of this storage method. The test found that 80kV? The hardness and soluble solid content of Red Star Apple stored at 0 ℃ and 90% humidity after three months were 10% and 1.5% higher than those of the control group respectively 8%, and the respiratory intensity decreases by about 10% [6]; Sichuan tangerine at 150kV? The good fruit rate was 49. 5% after 40 days of storage 7%, while the control group was 35%, and the color remained bright and bright; The preliminary electrostatic treatment experiment of honey peach also showed that the hardness and good fruit rate were higher than those of the control group [7]; 150kV? M high-voltage electric field treatment of litchi also achieved success [8]. Compared with the control group, the fruit not only extended the fresh-keeping period for 4 days, but also maintained the characteristics of hard and delicious taste except for the slightly darker color. In addition, there are Yali Pear stored at room temperature for 30 days, whose decay rate is 30% lower than that of the control group, and watermelon stored at room temperature for 30 days, whose decay rate is 80% lower than that of the control group [9]; It also has obvious effects on green pepper [10], citrus, cucumber, sweet potato, melon, etc. Therefore, electrostatic fresh-keeping storage is a better storage method for some difficult to store fruits and vegetables with high water content

from a large number of experimental results, high-voltage electrostatic field is beneficial to the growth of plants, the inhibition of microorganisms, the processing of agricultural products, especially the preservation and storage of fruits and vegetables. However, bioelectromagnetism is a new subject, which is an interdisciplinary subject that studies the relationship and interaction with animal and plant systems, and crosses the boundaries of physics, biology, postharvest physiology of fruits and vegetables and other disciplines. Therefore, the research on the storage of fruits and vegetables under electric field must be combined with relevant disciplines, which is very difficult. For a long time, the repeatability of experimental research is poor, and there is little mechanism research

therefore, China Agricultural University has carried out the following exploration in this field:

(1) obtain the physiological reaction law of fruits and vegetables in the process of electrostatic field preservation through experiments

(2) deeply analyze the distribution law of electric field and potential in fruits and vegetables under high voltage electrostatic field

(3) from the microscopic point of view, at the film level, the formula of graphene loaded into the masterbatch largely depends on the ultimate use to analyze and verify the mechanism of electrostatic preservation and storage of fruits and vegetables. By solving the electric field and potential inside and outside the fruit and vegetable cell membrane, the law of the change of the fruit and vegetable cell membrane potential under the action of the electric field is explored, and then the calculation model of the cell membrane potential is established by using the method of electromagnetic physics; The change law of membrane potential was verified by the measured data; The further research mechanism of cell physiological changes under electric field is proposed

(4) from the perspective of engineering practice, carry out systematic analysis to determine the control or influencing factors in electrostatic field storage, and through a large number of experiments, establish a mathematical model between various electric field factors and respiratory changes of fruits and vegetables under high-voltage electrostatic field, so as to establish an experimental and theoretical basis for further solving the long-term storage problem of some difficult to store fruits and vegetables

(5) discuss the operation characteristics of the storage system, provide feasibility analysis for the actual utilization of the system, and lay the foundation for the application of electromagnetic field theory in fruit and vegetable fresh storage engineering

3 further efforts

(1) continue to conduct comprehensive tracking research on the physiological process of fruits and vegetables stored under electrostatic field

(2) systematically study the effects of electrostatic treatment factors and storage system environmental factors on the storage process of fruits and vegetables

(3) improve the repeatability of the test and promote the development and utilization of this technology

(4 he said that the "people-oriented" reform will "integrate the economic, political, social and ecological environment") from the perspective of the mechanism of transmembrane potential difference, combined with the storage of fruits and vegetables, model analysis, calculation and experimental testing

Author: Wang Xiangyou, Liu Haibo, Li Ritter

reprinted from: China static electricity

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