真空(kong)袋(dai)(dai)的(de)(de)主(zhu)要作(zuo)用是除(chu)氧(yang)(yang)(yang)，以有(you)(you)利于防(fang)止(zhi)(zhi)食(shi)(shi)品(pin)(pin)變(bian)質(zhi)(zhi)，其(qi)(qi)原理也比較(jiao)簡單，因食(shi)(shi)品(pin)(pin)霉腐(fu)變(bian)質(zhi)(zhi)主(zhu)要由微生(sheng)(sheng)(sheng)(sheng)物(wu)(wu)的(de)(de)活動造成(cheng)，而大多數微生(sheng)(sheng)(sheng)(sheng)物(wu)(wu)（如(ru)霉菌和酵母菌）的(de)(de)生(sheng)(sheng)(sheng)(sheng)存是需(xu)要氧(yang)(yang)(yang)氣(qi)的(de)(de)，而真空(kong)包裝(zhuang)就是運用這個(ge)原理，把包裝(zhuang)袋(dai)(dai)內和食(shi)(shi)品(pin)(pin)細胞內的(de)(de)氧(yang)(yang)(yang)氣(qi)抽掉，使微物(wu)(wu)物(wu)(wu)失(shi)去“生(sheng)(sheng)(sheng)(sheng)存的(de)(de)環境”。實驗證明：當(dang)包裝(zhuang)袋(dai)(dai)內的(de)(de)氧(yang)(yang)(yang)氣(qi)濃(nong)度≤1%時，微生(sheng)(sheng)(sheng)(sheng)物(wu)(wu)的(de)(de)生(sheng)(sheng)(sheng)(sheng)長(chang)和繁殖(zhi)速度就急劇下(xia)降，氧(yang)(yang)(yang)氣(qi)濃(nong)度≤0.5%時，大多數微生(sheng)(sheng)(sheng)(sheng)物(wu)(wu)將受到抑(yi)制(zhi)(zhi)而停止(zhi)(zhi)繁殖(zhi)。（注(zhu)：真空(kong)包裝(zhuang)不(bu)能抑(yi)制(zhi)(zhi)厭氧(yang)(yang)(yang)菌的(de)(de)繁殖(zhi)和酶反應引起(qi)的(de)(de)食(shi)(shi)品(pin)(pin)變(bian)質(zhi)(zhi)和變(bian)色(se)，因此還需(xu)與其(qi)(qi)它輔助(zhu)方法(fa)結合，如(ru)冷藏、速凍、脫水(shui)、高(gao)溫殺菌、輻(fu)照 滅菌、微波殺菌、鹽(yan)腌制(zhi)(zhi)等。）真空(kong)除(chu)氧(yang)(yang)(yang)除(chu)了抑(yi)制(zhi)(zhi)微生(sheng)(sheng)(sheng)(sheng)物(wu)(wu)的(de)(de)生(sheng)(sheng)(sheng)(sheng)長(chang)和繁殖(zhi)外(wai)，另一個(ge)重要功能是防(fang)止(zhi)(zhi)食(shi)(shi)品(pin)(pin)氧(yang)(yang)(yang)化，因油(you)脂類食(shi)(shi)品(pin)(pin)中(zhong)含有(you)(you)大量不(bu)飽(bao)和脂肪酸，受氧(yang)(yang)(yang)的(de)(de)作(zuo)用而氧(yang)(yang)(yang)化，使食(shi)(shi)品(pin)(pin)變(bian)味(wei)、變(bian)質(zhi)(zhi)，此外(wai)，氧(yang)(yang)(yang)化還使維生(sheng)(sheng)(sheng)(sheng)素(su)A和C損(sun)失(shi)，食(shi)(shi)品(pin)(pin)色(se)素(su)中(zhong)的(de)(de)不(bu)穩定物(wu)(wu)質(zhi)(zhi)受氧(yang)(yang)(yang)的(de)(de)作(zuo)用，使顏色(se)變(bian)暗。所以，除(chu)氧(yang)(yang)(yang)能有(you)(you)效地防(fang)止(zhi)(zhi)食(shi)(shi)品(pin)(pin)變(bian)質(zhi)(zhi)，保持其(qi)(qi)色(se)、香、味(wei)及營養(yang)價值(zhi)。