真(zhen)空袋的(de)主(zhu)要(yao)(yao)作(zuo)用(yong)是(shi)除氧(yang)(yang)(yang)(yang)(yang)(yang)(yang)，以有(you)利于防(fang)止(zhi)(zhi)食品(pin)變(bian)(bian)質，其原理(li)(li)也比較簡(jian)單，因食品(pin)霉(mei)腐變(bian)(bian)質主(zhu)要(yao)(yao)由微(wei)(wei)(wei)生(sheng)(sheng)物(wu)(wu)的(de)活(huo)動(dong)造成(cheng)，而大多(duo)數微(wei)(wei)(wei)生(sheng)(sheng)物(wu)(wu)（如(ru)霉(mei)菌(jun)(jun)和酵母菌(jun)(jun)）的(de)生(sheng)(sheng)存(cun)(cun)是(shi)需要(yao)(yao)氧(yang)(yang)(yang)(yang)(yang)(yang)(yang)氣的(de)，而真(zhen)空包裝(zhuang)(zhuang)就(jiu)是(shi)運用(yong)這個原理(li)(li)，把包裝(zhuang)(zhuang)袋內(nei)和食品(pin)細(xi)胞內(nei)的(de)氧(yang)(yang)(yang)(yang)(yang)(yang)(yang)氣抽掉，使(shi)微(wei)(wei)(wei)物(wu)(wu)物(wu)(wu)失(shi)去“生(sheng)(sheng)存(cun)(cun)的(de)環(huan)境”。實驗證明：當包裝(zhuang)(zhuang)袋內(nei)的(de)氧(yang)(yang)(yang)(yang)(yang)(yang)(yang)氣濃度(du)≤1%時，微(wei)(wei)(wei)生(sheng)(sheng)物(wu)(wu)的(de)生(sheng)(sheng)長和繁(fan)(fan)(fan)殖速度(du)就(jiu)急劇下降，氧(yang)(yang)(yang)(yang)(yang)(yang)(yang)氣濃度(du)≤0.5%時，大多(duo)數微(wei)(wei)(wei)生(sheng)(sheng)物(wu)(wu)將受(shou)到抑(yi)制而停止(zhi)(zhi)繁(fan)(fan)(fan)殖。（注：真(zhen)空包裝(zhuang)(zhuang)不(bu)能(neng)抑(yi)制厭(yan)氧(yang)(yang)(yang)(yang)(yang)(yang)(yang)菌(jun)(jun)的(de)繁(fan)(fan)(fan)殖和酶反應引(yin)起的(de)食品(pin)變(bian)(bian)質和變(bian)(bian)色(se)，因此還(huan)(huan)需與其它輔(fu)助(zhu)方法結(jie)合，如(ru)冷藏(zang)、速凍、脫(tuo)水、高溫殺菌(jun)(jun)、輻照 滅(mie)菌(jun)(jun)、微(wei)(wei)(wei)波(bo)殺菌(jun)(jun)、鹽腌制等。）真(zhen)空除氧(yang)(yang)(yang)(yang)(yang)(yang)(yang)除了抑(yi)制微(wei)(wei)(wei)生(sheng)(sheng)物(wu)(wu)的(de)生(sheng)(sheng)長和繁(fan)(fan)(fan)殖外，另一個重要(yao)(yao)功能(neng)是(shi)防(fang)止(zhi)(zhi)食品(pin)氧(yang)(yang)(yang)(yang)(yang)(yang)(yang)化(hua)(hua)，因油脂(zhi)類食品(pin)中(zhong)含有(you)大量不(bu)飽和脂(zhi)肪(fang)酸，受(shou)氧(yang)(yang)(yang)(yang)(yang)(yang)(yang)的(de)作(zuo)用(yong)而氧(yang)(yang)(yang)(yang)(yang)(yang)(yang)化(hua)(hua)，使(shi)食品(pin)變(bian)(bian)味、變(bian)(bian)質，此外，氧(yang)(yang)(yang)(yang)(yang)(yang)(yang)化(hua)(hua)還(huan)(huan)使(shi)維生(sheng)(sheng)素A和C損失(shi)，食品(pin)色(se)素中(zhong)的(de)不(bu)穩定物(wu)(wu)質受(shou)氧(yang)(yang)(yang)(yang)(yang)(yang)(yang)的(de)作(zuo)用(yong)，使(shi)顏(yan)色(se)變(bian)(bian)暗。所以，除氧(yang)(yang)(yang)(yang)(yang)(yang)(yang)能(neng)有(you)效(xiao)地(di)防(fang)止(zhi)(zhi)食品(pin)變(bian)(bian)質，保(bao)持其色(se)、香、味及(ji)營(ying)養(yang)價值。