Views: 0 Author: Site Editor Publish Time: 2022-10-15 Origin: Site
使人类生存的空气里O2含量为20．98％(V／V) 人、动物、植物在呼吸时，都是从空气中吸进02 吐出CO2，从化学机理来讲．呼吸就是缓慢的氧化．为了抑制蔬菜、水果的呼吸强度，缓慢其新陈代谢过程，阻止发芽，放慢熟化过程，就采用提高CO 2含量降低O2含量，并使CO2和O2相对稳定于一定的比例之下，CO2还具有定菌作用，能抑制微生物细菌的繁衍。CO2气调法是一种不添加任何防腐剂的保鲜方法，该方法可靠性强，具有较大的应用价值在使用CO2保鲜同时目前也经常使用高纯氨N2 (99 .999％V／V)进行保鲜，现将经过长期试验及运用有利于保鲜贮藏和包装的CO2与O2 配气比值及相关技术参数，
C0 2对新鲜蔬菜及水果进行贮藏包装保蛘方面．具有一定的效果和有效性．实 践证明，对蛋类的保鲜也有成就．其原理是久放的蛋类，在其内部C02通过蛋壳上的微孔，逐渐释放．造成蛋中PH值增大，使蛋白缩合成水样蛋白，如果用30％一6o％(V／V) CO2充气包装，贮藏经6～10小时，包装内的CO2通过蛋壳微孔进入蛋内．能够延缓形成水样蛋白的速度，从而达到保鲜的目的。 用塑料食品包装袋或其他无毒密封容器包装海鱼、海产品，先将袋或容器抽成真空后，将21％(V／V)O2， 19％(V／V)N2 ，60％ (v／v)CO2的配比气注入．或以上述配比气置换袋或容器中空气，然后控制温度3℃左右，贮存十月其外形和鲜味与刚捕捞上来相差无几，故又称为无冰保鲜法。
在粮食的贮存方面用C02比通常的薰蒸剂效果好，美国艾尔科大米公司进行一系列大规模试验表明C02能穿透装有500吨大米的密封贮存库，在通人C02，24小时后，发现供试验用的大米中的成虫死掉99％，因此在欧洲、美洲、澳大利亚、日本等已普遍使用CO2来贮存粮食．我国北方和南方也有些地区已采用CO2来除去粮食中的米虫，取得较好的效果。是有利的，当然，对杀灭这些害虫也是有利的。实验室试验的很好参数为：温度为(25±3)℃；CO2气体浓度达到25 ～35（%V/V） ；谷蠹杀虫保持时间为72 h以上；米象杀虫保持时间为48 h以上，能1O0％的杀死储粮成虫。实验仓的试验验证了实验室的试验结果，杀虫的较好温度是(25士3)℃ ，但杀虫的持续时间应延长到10 d以上，CO2浓度达到25 ～35％ ，在气密性能良好的仓房内能100％消灭储粮成虫，达到防治效果。由此可见，CO2气调防治储粮害虫的方法是行之有效的。 国外制作汉堡牛排腊肠等内制品的过程中，把雪花状干冰直接添加到剁肉机和搅拌机中，利用固体C02急骤的冷却来降低内制品的温度、抑制细菌的繁殖，保持内制品新鲜，并以食品包装袋迅速将其包装以防止二次污染，从而达到无菌环境的加工要求。
CO2 mainly comes from synthetic ammonia tail gas, lime kiln release gas, CO2 natural gas well, wine and alcohol fermentation gas, blast furnace pipeline flue gas, etc. CO2 from different sources mentioned above is separated, recovered and purified after a series of physical and chemical processes. Use, such as for gas packaging, carbonated beverages, tobacco puffing, extraction of pharmaceutical products, etc., using CO2 to naturally reduce oxygen, and modified atmosphere preservation has become a relatively modern storage and packaging method commonly used in the world. CO2 modified atmosphere preservation is to inject high-purity CO2 (over 99.5% V/V) into a closed storage and packaging container to reduce the O2 content, inhibit biological respiration in fruits and vegetables, and curb the reproduction of germs to achieve the purpose of preservation. This method of using CO2 to prevent insects and keep fresh has been widely used, and even CO2 gas packaging is used in the military industry, such as the packaging of some high-precision components, components and anti-oxidation electronic components, CO2 laser weapons, etc. As we all know, fresh-keeping at home and abroad usually adopts: modified atmosphere fresh-keeping and vacuum fresh-keeping. In terms of modified atmosphere preservation, a large number of storage and preservation application tests have been done in China. Modified atmosphere preservation can only be said to be a relatively mature technology in storage and packaging preservation. In my country, CO2 has great application potential in preservation technology. Currently, it is mainly lacking. Promotion and application of technical personnel. As a result, it is not yet universally applicable. Because of its effectiveness in storage and packaging, modified atmosphere preservation has been well applied and promoted in many fields abroad.
The O2 content in the air that enables humans to live is 20.98% (V/V) When people, animals, and plants breathe, they all inhale O2 from the air and exhale CO2. From a chemical mechanism perspective. Breathing is slow oxidation. In order to inhibit the respiration intensity of vegetables and fruits, slow down their metabolic process, prevent germination, and slow down the ripening process, the CO2 content is increased to reduce the O2 content, and the CO2 and O2 are relatively stable under a certain ratio. Bacterial effect, can inhibit the reproduction of microbial bacteria. CO2 modified atmosphere method is a fresh-keeping method without adding any preservatives. This method is highly reliable and has great application value. At the same time, high-purity ammonia N2 (99 .999% V/V) is often used for fresh-keeping with CO2. For fresh-keeping, the gas distribution ratio and related technical parameters of CO2 and O2, which are beneficial to fresh-keeping storage and packaging, will now be used after long-term experiments.
CO2 stored in modified atmosphere packaging: The gas must meet the national standard GB1917-94 (fermentation method) food additive CO2 standard and GB10621-89 (lime kiln method and synthetic ammonia method) food additive CO2 standard (including other gases used in gas packaging , and must also be issued to meet the standards) Can not use any direct source of CO2 gas containing toxic and harmful impurity components without separation and purification, which must be strictly required in the modified atmosphere method. In gas packaging, only gas preservation is concerned, and Not to mention the gas quality and the influence of gas quality on packaging and storage items, this is a vague concept.
C0 2 Storage, packaging and preservation of fresh vegetables and fruits. Has a certain effect and effectiveness. Practice has proved that the preservation of eggs also has achievements. The principle is that in eggs that have been laid for a long time, C02 is gradually released through the micropores on the eggshell. Cause the pH value in the egg to increase, so that the protein is condensed into water-like protein. If it is air-packed with 30%-6o% (V/V) CO2, and stored for 6 to 10 hours, the CO2 in the package will enter the egg through the eggshell micropores. Inside. It can delay the formation of water-like protein, so as to achieve the purpose of preservation. Use plastic food packaging bags or other non-toxic airtight containers to pack marine fish and seafood. After the bag or container is evacuated, 21%(V/V)O2, 19%(V/V)N2 , 60% (v /v) Proportional gas injection of CO2. Or replace the air in the bag or container with the above-mentioned proportion of gas, and then control the temperature to about 3 ℃, and store it in October.
In the storage of grain, the effect of using C02 is better than that of the usual fumigant. A series of large-scale experiments conducted by the American Alco Rice Company show that C02 can penetrate the sealed storage warehouse containing 500 tons of rice. Later, it was found that 99% of the adult worms in the rice used for the test died, so CO2 has been widely used to store food in Europe, America, Australia, Japan, etc. In some areas in northern and southern my country, CO2 has been used to remove rice worms in food, and good results have been achieved. It is beneficial, of course, to kill these pests. The good parameters of the laboratory test are: the temperature is (25±3)℃; the CO2 gas concentration reaches 25 ～35(%V/V) ; the insecticidal holding time of the beetle is more than 72 h; the rice weevil insecticidal holding time is More than 48 hours, it can kill 100% of stored grain adults. The experiment in the experimental chamber verified the results of the laboratory test. The best temperature for insecticide is (25±3)℃ , but the duration of insecticidal should be extended to more than 10 d, and the CO2 concentration should reach 25 ～35% . In the warehouse with good performance, 100% of the stored grain worms can be eliminated, and the control effect can be achieved. It can be seen that the CO2-controlled atmosphere method is effective for controlling stored grain pests. In the process of making hamburger steak sausages and other internal products abroad, the snowflake-shaped dry ice is directly added to the meat chopper and mixer, and the solid CO2 is used for rapid cooling to reduce the temperature of the internal products, inhibit the reproduction of bacteria, and keep the internal products fresh. It is quickly packaged in food packaging bags to prevent secondary pollution, so as to meet the processing requirements of aseptic environment.
CO2 is inseparable from modified atmosphere fresh-keeping storage packaging, and it has a large potential commercial packaging market. Therefore, the modified atmosphere packaging machine for food has become a market trend of food packaging. As early as the middle of the last century, foreign developed regions have used the modified atmosphere preservation technology for food packaging, and are favored by consumers.