真空(kong)充(chong)(chong)(chong)氣(qi)(qi)包裝(zhuang)在真空(kong)后再充(chong)(chong)(chong)入氮氣(qi)(qi)、二氧(yang)(yang)化碳(tan)(tan)、氧(yang)(yang)氣(qi)(qi)單一氣(qi)(qi)體(ti)(ti)或(huo)(huo)二、三(san)種(zhong)氣(qi)(qi)體(ti)(ti)的(de)混合氣(qi)(qi)體(ti)(ti)。其(qi)(qi)氮氣(qi)(qi)是惰(duo)性氣(qi)(qi)體(ti)(ti)，起(qi)充(chong)(chong)(chong)填(tian)作用(yong)(yong)，使(shi)袋(dai)內保(bao)(bao)持正(zheng)壓，以防止(zhi)袋(dai)外(wai)空(kong)氣(qi)(qi)進(jin)入袋(dai)內，對食品起(qi)到(dao)一個保(bao)(bao)護作用(yong)(yong)。其(qi)(qi)二氧(yang)(yang)化碳(tan)(tan)能夠(gou)溶(rong)于各類脂肪或(huo)(huo)水，引成(cheng)酸性較弱的(de)碳(tan)(tan)酸，有抑制霉菌、腐敗細菌等微生(sheng)物的(de)活性。其(qi)(qi)氧(yang)(yang)氣(qi)(qi)具(ju)有抑制厭氧(yang)(yang)菌的(de)生(sheng)長繁(fan)殖，保(bao)(bao)持水果、蔬菜的(de)新(xin)鮮(xian)及色彩，高濃度(du)氧(yang)(yang)氣(qi)(qi)可使(shi)新(xin)鮮(xian)肉類保(bao)(bao)持其(qi)(qi)鮮(xian)紅(hong)色。