真空充(chong)氣包裝的主(zhu)要作(zuo)用(yong)除(chu)真空包裝所具備的除(chu)氧保質功能外，主(zhu)要還有抗壓、阻氣、保鮮等作(zuo)用(yong)，能更有(you)效(xiao)地(di)(di)使(shi)食(shi)(shi)(shi)品長期保持原有(you)的(de)(de)色、香、味、形及(ji)營養價值。另(ling)外(wai)，有(you)許多食(shi)(shi)(shi)品不適宜采(cai)(cai)用(yong)真空(kong)(kong)包(bao)(bao)裝(zhuang)(zhuang)(zhuang)(zhuang)(zhuang)而(er)必須采(cai)(cai)用(yong)真空(kong)(kong)充(chong)(chong)(chong)(chong)氣(qi)包(bao)(bao)裝(zhuang)(zhuang)(zhuang)(zhuang)(zhuang)。如(ru)松脆易碎(sui)食(shi)(shi)(shi)品，易結塊食(shi)(shi)(shi)品，易變形走油食(shi)(shi)(shi)品，有(you)尖(jian)銳棱角或(huo)硬(ying)度(du)較高會刺破(po)包(bao)(bao)裝(zhuang)(zhuang)(zhuang)(zhuang)(zhuang)袋的(de)(de)食(shi)(shi)(shi)品等。食(shi)(shi)(shi)品經真空(kong)(kong)充(chong)(chong)(chong)(chong)氣(qi)包(bao)(bao)裝(zhuang)(zhuang)(zhuang)(zhuang)(zhuang)后，包(bao)(bao)裝(zhuang)(zhuang)(zhuang)(zhuang)(zhuang)袋內充(chong)(chong)(chong)(chong)氣(qi)壓強大于(yu)包(bao)(bao)裝(zhuang)(zhuang)(zhuang)(zhuang)(zhuang)袋外(wai)大氣(qi)壓強，能有(you)效(xiao)地(di)(di)防止食(shi)(shi)(shi)品受壓破(po)碎(sui)變形并不影響包(bao)(bao)裝(zhuang)(zhuang)(zhuang)(zhuang)(zhuang)袋外(wai)觀及(ji) 印刷裝(zhuang)(zhuang)(zhuang)(zhuang)(zhuang)潢。真空(kong)(kong)充(chong)(chong)(chong)(chong)氣(qi)包(bao)(bao)裝(zhuang)(zhuang)(zhuang)(zhuang)(zhuang)在真空(kong)(kong)后再充(chong)(chong)(chong)(chong)入氮氣(qi)、二氧化碳、氧氣(qi)單一氣體或二(er) 三種氣(qi)體的(de)(de)混合氣(qi)體。其氮氣(qi)是惰(duo)性氣(qi)體，起充(chong)填作(zuo)用，使(shi)袋內保(bao)持正壓(ya) ，以(yi)防止袋外(wai)空(kong)氣(qi)進入袋內，對食品起到一(yi)個保(bao)護(hu)作(zuo)用。其二(er)氧化碳能(neng)夠溶于各類脂肪或水(shui)，引成酸性較弱(ruo)的(de)(de)碳酸，有抑制霉菌、腐敗細菌等微(wei)生物的(de)(de)活性。其氧氣(qi)具有抑制厭氧菌的(de)(de)生長繁殖，保(bao)持水(shui)果、蔬菜的(de)(de)新鮮及色彩，高濃度氧氣(qi)可使(shi)新鮮肉類保(bao)持其鮮紅(hong)色。