真空(kong)充(chong)氣(qi)(qi)包裝在真空(kong)后再充(chong)入氮(dan)氣(qi)(qi)、二(er)(er)氧化(hua)碳、氧氣(qi)(qi)單(dan)一(yi)(yi)氣(qi)(qi)體或(huo)(huo)二(er)(er) 三種氣(qi)(qi)體的混合氣(qi)(qi)體。其(qi)(qi)(qi)氮(dan)氣(qi)(qi)是惰性氣(qi)(qi)體，起充(chong)填作用，使袋內保(bao)(bao)持(chi)(chi)正壓 ，以防止(zhi)袋外空(kong)氣(qi)(qi)進入袋內，對食品起到一(yi)(yi)個保(bao)(bao)護作用。其(qi)(qi)(qi)二(er)(er)氧化(hua)碳能夠溶于(yu)各類脂肪(fang)或(huo)(huo)水，引(yin)成酸性較弱的碳酸，有抑(yi)制(zhi)霉菌、腐敗細菌等微生(sheng)(sheng)物的活性。其(qi)(qi)(qi)氧氣(qi)(qi)具有抑(yi)制(zhi)厭(yan)氧菌的生(sheng)(sheng)長(chang)繁殖，保(bao)(bao)持(chi)(chi)水果、蔬(shu)菜(cai)的新鮮(xian)(xian)及色彩，高(gao)濃(nong)度氧氣(qi)(qi)可使新鮮(xian)(xian)肉(rou)類保(bao)(bao)持(chi)(chi)其(qi)(qi)(qi)鮮(xian)(xian)紅色。水果蔬(shu)菜(cai)的新鮮(xian)(xian)可是營養不流失。