真空(kong)(kong)充(chong)(chong)氣(qi)(qi)(qi)包裝在真空(kong)(kong)后再充(chong)(chong)入氮氣(qi)(qi)(qi)、二(er)氧(yang)化碳(tan)、氧(yang)氣(qi)(qi)(qi)單(dan)一(yi)氣(qi)(qi)(qi)體或二(er) 三(san)種氣(qi)(qi)(qi)體的(de)混合氣(qi)(qi)(qi)體。其氮氣(qi)(qi)(qi)是(shi)惰性(xing)氣(qi)(qi)(qi)體，起(qi)充(chong)(chong)填(tian)作(zuo)用(yong)，使袋內保持(chi)正壓(ya) ，以防止(zhi)袋外(wai)空(kong)(kong)氣(qi)(qi)(qi)進入袋內，對食品起(qi)到一(yi)個保護(hu)作(zuo)用(yong)。其二(er)氧(yang)化碳(tan)能夠溶于各(ge)類(lei)脂(zhi)肪或水，引成酸性(xing)較弱(ruo)的(de)碳(tan)酸，有抑制(zhi)霉菌(jun)(jun)、腐敗(bai)細菌(jun)(jun)等(deng)微生物的(de)活(huo)性(xing)。其氧(yang)氣(qi)(qi)(qi)具有抑制(zhi)厭氧(yang)菌(jun)(jun)的(de)生長繁殖，保持(chi)水果(guo)、蔬菜(cai)的(de)新(xin)鮮(xian)(xian)及色彩，高濃(nong)度氧(yang)氣(qi)(qi)(qi)可使新(xin)鮮(xian)(xian)肉類(lei)保持(chi)其鮮(xian)(xian)紅色。水果(guo)蔬菜(cai)的(de)新(xin)鮮(xian)(xian)可是(shi)營養不流失。