真空袋的主(zhu)要作用(yong)是除(chu)氧(yang)(yang)(yang)，以有(you)利于(yu)防(fang)(fang)止(zhi)(zhi)食(shi)(shi)品(pin)(pin)變(bian)(bian)質，其(qi)(qi)原理(li)也比較(jiao)簡(jian)單，因(yin)食(shi)(shi)品(pin)(pin)霉腐變(bian)(bian)質主(zhu)要由(you)微生(sheng)(sheng)(sheng)物(wu)(wu)的活(huo)動造成，而(er)大(da)多數微生(sheng)(sheng)(sheng)物(wu)(wu)（如(ru)(ru)霉菌(jun)和(he)酵母菌(jun)）的生(sheng)(sheng)(sheng)存是需要氧(yang)(yang)(yang)氣(qi)的，而(er)真空包(bao)裝(zhuang)(zhuang)就是運用(yong)這個原理(li)，把包(bao)裝(zhuang)(zhuang)袋內(nei)和(he)食(shi)(shi)品(pin)(pin)細胞內(nei)的氧(yang)(yang)(yang)氣(qi)抽掉，使(shi)微物(wu)(wu)物(wu)(wu)失去(qu)“生(sheng)(sheng)(sheng)存的環境(jing)”。實驗(yan)證明：當包(bao)裝(zhuang)(zhuang)袋內(nei)的氧(yang)(yang)(yang)氣(qi)濃度≤1%時，微生(sheng)(sheng)(sheng)物(wu)(wu)的生(sheng)(sheng)(sheng)長和(he)繁殖(zhi)速(su)度就急劇(ju)下降，氧(yang)(yang)(yang)氣(qi)濃度≤0.5%時，大(da)多數微生(sheng)(sheng)(sheng)物(wu)(wu)將受到(dao)抑制而(er)停止(zhi)(zhi)繁殖(zhi)。（注：真空包(bao)裝(zhuang)(zhuang)不能(neng)抑制厭氧(yang)(yang)(yang)菌(jun)的繁殖(zhi)和(he)酶反(fan)應引起的食(shi)(shi)品(pin)(pin)變(bian)(bian)質和(he)變(bian)(bian)色，因(yin)此(ci)還(huan)需與其(qi)(qi)它輔助(zhu)方法結合，如(ru)(ru)冷藏、速(su)凍、脫(tuo)水、高(gao)溫(wen)殺(sha)菌(jun)、輻(fu)照(zhao) 滅菌(jun)、微波殺(sha)菌(jun)、鹽腌制等。）真空除(chu)氧(yang)(yang)(yang)除(chu)了抑制微生(sheng)(sheng)(sheng)物(wu)(wu)的生(sheng)(sheng)(sheng)長和(he)繁殖(zhi)外(wai)，另(ling)一個重要功能(neng)是防(fang)(fang)止(zhi)(zhi)食(shi)(shi)品(pin)(pin)氧(yang)(yang)(yang)化(hua)(hua)，因(yin)油(you)脂(zhi)類食(shi)(shi)品(pin)(pin)中(zhong)含有(you)大(da)量不飽(bao)和(he)脂(zhi)肪酸(suan)，受氧(yang)(yang)(yang)的作用(yong)而(er)氧(yang)(yang)(yang)化(hua)(hua)，使(shi)食(shi)(shi)品(pin)(pin)變(bian)(bian)味、變(bian)(bian)質，此(ci)外(wai)，氧(yang)(yang)(yang)化(hua)(hua)還(huan)使(shi)維生(sheng)(sheng)(sheng)素A和(he)C損失，食(shi)(shi)品(pin)(pin)色素中(zhong)的不穩定物(wu)(wu)質受氧(yang)(yang)(yang)的作用(yong)，使(shi)顏色變(bian)(bian)暗。所以，除(chu)氧(yang)(yang)(yang)能(neng)有(you)效地防(fang)(fang)止(zhi)(zhi)食(shi)(shi)品(pin)(pin)變(bian)(bian)質，保持其(qi)(qi)色、香(xiang)、味及營養價(jia)值。