真空(kong)充(chong)氣包(bao)裝的主要(yao)作用除真空(kong)包(bao)裝所具備的除氧(yang)保質(zhi)功能外，主要(yao)還有抗壓(ya)、阻氣(qi)、保鮮等作用(yong)，能(neng)更有(you)效地(di)使食(shi)(shi)(shi)(shi)品(pin)長期(qi)保持原有(you)的色、香(xiang)、味(wei)、形及營養價值。另外(wai)(wai)，有(you)許多食(shi)(shi)(shi)(shi)品(pin)不適宜采用(yong)真空(kong)(kong)包裝(zhuang)(zhuang)而必(bi)須采用(yong)真空(kong)(kong)充(chong)氣(qi)包裝(zhuang)(zhuang)。如(ru)松脆易碎食(shi)(shi)(shi)(shi)品(pin)，易結塊食(shi)(shi)(shi)(shi)品(pin)，易變形走(zou)油食(shi)(shi)(shi)(shi)品(pin)，有(you)尖銳棱(leng)角或硬(ying)度較高會刺破包裝(zhuang)(zhuang)袋(dai)的食(shi)(shi)(shi)(shi)品(pin)等。食(shi)(shi)(shi)(shi)品(pin)經真空(kong)(kong)充(chong)氣(qi)包裝(zhuang)(zhuang)后，包裝(zhuang)(zhuang)袋(dai)內(nei)充(chong)氣(qi)壓(ya)強大于包裝(zhuang)(zhuang)袋(dai)外(wai)(wai)大氣(qi)壓(ya)強，能(neng)有(you)效地(di)防止(zhi)食(shi)(shi)(shi)(shi)品(pin)受壓(ya)破碎變形并不影(ying)響包裝(zhuang)(zhuang)袋(dai)外(wai)(wai)觀及 印刷裝(zhuang)(zhuang)潢。真空(kong)(kong)充(chong)氣(qi)包裝(zhuang)(zhuang)在真空(kong)(kong)后再充(chong)入氮(dan)氣(qi)、二氧(yang)化碳、氧(yang)氣(qi)單一氣體或(huo)二 三種氣體的混合氣體。其(qi)氮氣是惰(duo)性氣體，起(qi)充填(tian)作(zuo)用，使袋內保持(chi)(chi)(chi)正壓(ya) ，以防(fang)止袋外(wai)空氣進(jin)入袋內，對食品起(qi)到(dao)一(yi)個保護作(zuo)用。其(qi)二氧(yang)(yang)化碳(tan)能夠溶(rong)于各(ge)類脂肪(fang)或(huo)水，引成酸(suan)性較弱的碳(tan)酸(suan)，有抑(yi)制霉菌、腐敗細菌等(deng)微生物的活性。其(qi)氧(yang)(yang)氣具(ju)有抑(yi)制厭氧(yang)(yang)菌的生長繁殖，保持(chi)(chi)(chi)水果、蔬(shu)菜的新鮮及色彩，高濃度(du)氧(yang)(yang)氣可使新鮮肉類保持(chi)(chi)(chi)其(qi)鮮紅(hong)色。