真(zhen)空(kong)(kong)充(chong)氣(qi)(qi)(qi)(qi)(qi)包裝在真(zhen)空(kong)(kong)后再充(chong)入氮(dan)氣(qi)(qi)(qi)(qi)(qi)、二(er)氧化(hua)碳、氧氣(qi)(qi)(qi)(qi)(qi)單一(yi)氣(qi)(qi)(qi)(qi)(qi)體或二(er) 三種氣(qi)(qi)(qi)(qi)(qi)體的混合(he)氣(qi)(qi)(qi)(qi)(qi)體。其(qi)氮(dan)氣(qi)(qi)(qi)(qi)(qi)是惰性氣(qi)(qi)(qi)(qi)(qi)體，起(qi)充(chong)填作用(yong)，使(shi)袋內(nei)保(bao)持正(zheng)壓 ，以(yi)防止袋外空(kong)(kong)氣(qi)(qi)(qi)(qi)(qi)進入袋內(nei)，對食品起(qi)到一(yi)個保(bao)護作用(yong)。其(qi)二(er)氧化(hua)碳能夠溶(rong)于各類脂肪(fang)或水(shui)，引成(cheng)酸性較弱的碳酸，有抑(yi)制霉菌(jun)、腐(fu)敗細菌(jun)等(deng)微生物的活性。其(qi)氧氣(qi)(qi)(qi)(qi)(qi)具(ju)有抑(yi)制厭氧菌(jun)的生長(chang)繁(fan)殖，保(bao)持水(shui)果(guo)、蔬(shu)菜的新(xin)鮮(xian)及(ji)色彩，高濃度氧氣(qi)(qi)(qi)(qi)(qi)可使(shi)新(xin)鮮(xian)肉類保(bao)持其(qi)鮮(xian)紅色。水(shui)果(guo)蔬(shu)菜的新(xin)鮮(xian)可是營養不流失。