真空(kong)充(chong)(chong)氣(qi)(qi)包裝在真空(kong)后再(zai)充(chong)(chong)入氮氣(qi)(qi)、二(er)氧(yang)化碳、氧(yang)氣(qi)(qi)單一(yi)氣(qi)(qi)體(ti)或二(er) 三種氣(qi)(qi)體(ti)的(de)混合氣(qi)(qi)體(ti)。其(qi)(qi)氮氣(qi)(qi)是惰性(xing)氣(qi)(qi)體(ti)，起充(chong)(chong)填作用(yong)，使(shi)袋內(nei)保(bao)持正壓 ，以防止袋外空(kong)氣(qi)(qi)進入袋內(nei)，對食品起到一(yi)個(ge)保(bao)護作用(yong)。其(qi)(qi)二(er)氧(yang)化碳能夠溶(rong)于各類(lei)(lei)脂(zhi)肪或水(shui)，引成酸性(xing)較弱的(de)碳酸，有(you)(you)抑(yi)制霉菌、腐(fu)敗細(xi)菌等微生物的(de)活性(xing)。其(qi)(qi)氧(yang)氣(qi)(qi)具有(you)(you)抑(yi)制厭(yan)氧(yang)菌的(de)生長(chang)繁殖，保(bao)持水(shui)果(guo)、蔬菜的(de)新鮮(xian)(xian)(xian)及(ji)色(se)彩，高濃(nong)度氧(yang)氣(qi)(qi)可使(shi)新鮮(xian)(xian)(xian)肉類(lei)(lei)保(bao)持其(qi)(qi)鮮(xian)(xian)(xian)紅(hong)色(se)。水(shui)果(guo)蔬菜的(de)新鮮(xian)(xian)(xian)可是營養不流失。