真空充(chong)氣(qi)(qi)(qi)(qi)(qi)(qi)包裝在真空后再充(chong)入(ru)氮氣(qi)(qi)(qi)(qi)(qi)(qi)、二氧(yang)(yang)(yang)化(hua)碳、氧(yang)(yang)(yang)氣(qi)(qi)(qi)(qi)(qi)(qi)單(dan)一氣(qi)(qi)(qi)(qi)(qi)(qi)體或(huo)二、三(san)種氣(qi)(qi)(qi)(qi)(qi)(qi)體的混合氣(qi)(qi)(qi)(qi)(qi)(qi)體。其氮氣(qi)(qi)(qi)(qi)(qi)(qi)是惰性(xing)氣(qi)(qi)(qi)(qi)(qi)(qi)體，起充(chong)填作用(yong)，使(shi)袋內保(bao)持(chi)正(zheng)壓，以(yi)防止(zhi)袋外空氣(qi)(qi)(qi)(qi)(qi)(qi)進入(ru)袋內，對食(shi)品起到一個保(bao)護作用(yong)。其二氧(yang)(yang)(yang)化(hua)碳能夠(gou)溶于各類脂(zhi)肪或(huo)水(shui)(shui)，引(yin)成酸(suan)性(xing)較弱的碳酸(suan)，有(you)抑(yi)制霉菌、腐敗(bai)細菌等微生(sheng)(sheng)物(wu)的活性(xing)。其氧(yang)(yang)(yang)氣(qi)(qi)(qi)(qi)(qi)(qi)具有(you)抑(yi)制厭氧(yang)(yang)(yang)菌的生(sheng)(sheng)長繁殖，保(bao)持(chi)水(shui)(shui)果、蔬(shu)菜的新鮮(xian)及色(se)彩，高濃(nong)度氧(yang)(yang)(yang)氣(qi)(qi)(qi)(qi)(qi)(qi)可(ke)使(shi)新鮮(xian)肉類保(bao)持(chi)其鮮(xian)紅(hong)色(se)。