Application of Oxygen and CO2 in Suction Gas Detector for Fruits and Vegetables
Fresh fruits and vegetables are still alive after picking, carrying out metabolic activities dominated by respiration. Due to being separated from the parent body, the supply of materials and energy is interrupted, and life can only be maintained by consuming carbohydrates, pectin, vitamins, organic acids and other substances in the fruit, which will inevitably lead to a decline in the quality of fruits and vegetables. The core issue of fresh fruits and vegetables is how to slow down breathing, inhibit metabolism, and make fresh fruits and vegetables in a dormant or semi-dormant state. In addition to the method of refrigeration, the commonly used methods of preservation of fruits and vegetables are refrigeration in controlled atmosphere warehouses or composite modified atmosphere packaging plus refrigeration. At present, the most advanced fresh-keeping method in the world is the use of composite modified atmosphere packaging and refrigeration, which can achieve a perfect combination of modified atmosphere chain and cold storage chain.
The principle of composite modified atmosphere fresh-keeping packaging is to use composite fresh-keeping gas to replace the air in plastic bags or packaging boxes that have been loaded with fruits and vegetables, change the gas ratio in plastic bags or packaging boxes, and form micro air in bags or boxes. Adjusting the environment—that is, forming a micro-air conditioning warehouse, coupled with refrigeration, so as to slow down the metabolism of fresh fruits and vegetables and prolong the freshness of fruits and vegetables.
Modified atmosphere fresh-keeping gas is generally composed of carbon dioxide (CO2), nitrogen (N2), oxygen (O2) and so on. Reducing the O2 content can slow down the respiration of fruits and vegetables and inhibit metabolism; appropriately increasing the concentration of CO2 gas can further slow down the respiration of fruits and vegetables; When the packaging communicates with the outside air, it plays a role in controlling the mixing ratio. Different food fruits and vegetables have different composition and proportion of fresh-keeping gas, which mainly depends on some characteristics of different fruits and vegetables themselves. Therefore, in order to achieve modified atmosphere preservation of fruits and vegetables, it is necessary to analyze the gas composition in the modified atmosphere packaging. It is necessary to equip a "gas detector" to analyze the gas composition in the modified atmosphere packaging, and to choose the best combination with specific actual tests. Compare. The gas analyzer is equipped with an oxygen sensor and a CO2 sensor at the same time, which can test the content of oxygen and carbon dioxide at the same time. It is specially used for the determination of the content and mixing ratio of oxygen and carbon dioxide in sealed packaging bags, bottles, cans and other packages; it is suitable for production lines, Quickly and accurately evaluate the content and proportion of gas components in packages in warehouses, laboratories, etc., so as to guide production and ensure the realization of product shelf life.
The sensor for detecting O2 and CO2 content in the gas detector, ISweek Gongcai.com recommends that the oxygen sensor use the fluorescence principle Lox-02 fluorescent oxygen sensor (O2 concentration range 0-25%) and the high-speed response infrared carbon dioxide sensor SprintIR, through accurate measurement The concentration of oxygen and carbon dioxide is used to adjust the atmosphere in the modified atmosphere packaging, thereby prolonging the freshness of fresh fruits and vegetables.
In addition, the freshness of fruits and vegetables also has the important problem of water penetration. Once the water is lost, it will have a great impact on the taste of the product. Some units use the method of injecting a small amount of water into the packaging, but this method is not advisable, because if the moisture in the packaging is too large, it will accelerate the spoilage of the product. In fact, this problem can be solved by controlling the permeability (permeability or barrier performance) of the packaging to water vapor. Selecting appropriate materials can reduce the outward penetration of water and at the same time reasonably control the penetration of compound gas.
