Fresh fruits and vegetables are still living organisms after harvesting, and carry out metabolic activities dominated by respiration. Because of the separation from the mother, the material and energy supply is interrupted, and only by consuming carbohydrates, pectin, vitamins, organic acids and other substances in the fruit to sustain life, this will inevitably lead to a decline in the quality of fruits and vegetables. The core problem of fruit and vegetable preservation 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 refrigerating, the commonly used methods for preserving fruits and vegetables are air-conditioning or refrigerated packaging and refrigeration. At present, the international advanced preservation method adopts composite air-conditioning packaging and refrigeration, which can achieve a perfect combination of air-conditioning chain and cold chain.
The principle of the composite modified atmosphere packaging is to replace the air in the plastic bag or the packaging box filled with fruits and vegetables with the composite fresh-keeping gas, and change the gas ratio in the plastic bag or the packaging box to form the micro gas in the bag or in the box. Adjust the environment - that is, the formation of a micro-acoustic library, coupled with refrigeration, so as to slow down the metabolism of fresh fruits and vegetables, and extend the preservation of fruits and vegetables.
The modified atmosphere gas is generally composed of carbon dioxide (CO2), nitrogen (N2), oxygen (O2) and the like. Reducing the O2 content can slow the breathing of fruits and vegetables and inhibit metabolism; properly increasing the concentration of CO2 gas can further slow the breathing of fruits and vegetables; N2 is an inert gas, and does not work with fruits and vegetables, but it is not only used as a filling gas, but in the atmosphere When the package communicates with the outside air, it plays a role in controlling the mixing ratio. Different foods and vegetables, the composition and proportion of fresh gas are different, depending on some characteristics of different fruits and vegetables. Therefore, in order to achieve fresh-keeping of fruits and vegetables, it is necessary to analyze the gas components in the modified atmosphere packaging. It is necessary to equip the “top air analyzer†for the analysis of the internal gas components of the modified atmosphere packaging, and to select the best with the actual actual test. Matching.
The HGA-01 top air body analyzer manufactured by Labthink () is specialized in sealing oxygen, carbon dioxide gas content in packaging bags, bottles, cans, etc. Determination of mixing ratio; suitable for quickly and accurately evaluating the content and proportion of gas components in the package in production lines, warehouses, laboratories, etc., thereby guiding production and ensuring the shelf life of the product.
In addition, fresh fruits and vegetables, as well as important problems of water penetration, once the water loss will have a great impact on the taste of the product. Some units use a small amount of water in the package, but this method is not preferable because if the moisture in the package is too high, the product will be spoiled. In fact, this problem can be solved by controlling the permeability of the package for water vapor transmission (barrier or barrier properties). The selection of suitable materials can reduce the outward penetration of moisture while controlling the penetration of the composite gas. Specific testing requires the use of water vapor transmission rate testing equipment, such as TSY-T series moisture permeability tester, PERME W3/330, etc. are ideal choices. Of course, the control of the barrier performance is inseparable from the control of the gas permeation amount, and the quality control can be performed by the VAC-V1 and VAC-V2 differential pressure gas permeation instruments.
In fact, regarding the control of the preservation of fruits and vegetables through modified atmosphere packaging, relevant institutions and scientific research departments in various countries are conducting research. This is a systematic project. There are many other detection projects in addition to barrier performance and headspace analysis. However, both the scientific research institutions and the premise of enterprise control and research need to be equipped with professional top air analyzers and instruments such as gas permeability testers and moisture permeability testers.