真空(kong)充(chong)氣(qi)(qi)(qi)包裝在真空(kong)后(hou)再充(chong)入氮氣(qi)(qi)(qi)、二氧(yang)化碳、氧(yang)氣(qi)(qi)(qi)單(dan)一(yi)氣(qi)(qi)(qi)體或二 三種氣(qi)(qi)(qi)體的混(hun)合氣(qi)(qi)(qi)體。其(qi)(qi)氮氣(qi)(qi)(qi)是(shi)惰性(xing)氣(qi)(qi)(qi)體，起充(chong)填作用(yong)，使(shi)袋(dai)內(nei)保(bao)持正壓 ，以(yi)防(fang)止(zhi)袋(dai)外空(kong)氣(qi)(qi)(qi)進入袋(dai)內(nei)，對食品(pin)起到(dao)一(yi)個(ge)保(bao)護(hu)作用(yong)。其(qi)(qi)二氧(yang)化碳能夠溶于各類(lei)(lei)脂肪或水(shui)，引成酸性(xing)較弱的碳酸，有(you)抑制(zhi)霉(mei)菌、腐(fu)敗細菌等微(wei)生物的活性(xing)。其(qi)(qi)氧(yang)氣(qi)(qi)(qi)具有(you)抑制(zhi)厭氧(yang)菌的生長繁殖(zhi)，保(bao)持水(shui)果(guo)(guo)、蔬菜的新(xin)鮮(xian)(xian)(xian)及(ji)色(se)彩，高(gao)濃度氧(yang)氣(qi)(qi)(qi)可使(shi)新(xin)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)(guo)蔬菜的新(xin)鮮(xian)(xian)(xian)可是(shi)營養不流失。