真空(kong)(kong)(kong)袋(dai)(dai)的(de)(de)(de)主要作(zuo)用是(shi)除(chu)氧(yang)(yang)(yang)(yang)(yang)(yang)，以有(you)利于防(fang)止(zhi)(zhi)食(shi)(shi)品(pin)變(bian)(bian)(bian)質，其原理也比較(jiao)簡(jian)單，因食(shi)(shi)品(pin)霉(mei)腐變(bian)(bian)(bian)質主要由微(wei)生(sheng)(sheng)物的(de)(de)(de)活(huo)動造成(cheng)，而(er)大多數(shu)微(wei)生(sheng)(sheng)物（如霉(mei)菌(jun)和(he)(he)酵母菌(jun)）的(de)(de)(de)生(sheng)(sheng)存是(shi)需要氧(yang)(yang)(yang)(yang)(yang)(yang)氣(qi)的(de)(de)(de)，而(er)真空(kong)(kong)(kong)包裝就是(shi)運用這個原理，把(ba)包裝袋(dai)(dai)內(nei)和(he)(he)食(shi)(shi)品(pin)細(xi)胞(bao)內(nei)的(de)(de)(de)氧(yang)(yang)(yang)(yang)(yang)(yang)氣(qi)抽掉，使(shi)(shi)微(wei)物物失去“生(sheng)(sheng)存的(de)(de)(de)環境(jing)”。實驗證(zheng)明：當包裝袋(dai)(dai)內(nei)的(de)(de)(de)氧(yang)(yang)(yang)(yang)(yang)(yang)氣(qi)濃度≤1%時(shi)(shi)，微(wei)生(sheng)(sheng)物的(de)(de)(de)生(sheng)(sheng)長(chang)(chang)和(he)(he)繁(fan)(fan)(fan)殖(zhi)(zhi)速度就急劇下降，氧(yang)(yang)(yang)(yang)(yang)(yang)氣(qi)濃度≤0.5%時(shi)(shi)，大多數(shu)微(wei)生(sheng)(sheng)物將(jiang)受到抑制(zhi)(zhi)而(er)停止(zhi)(zhi)繁(fan)(fan)(fan)殖(zhi)(zhi)。（注(zhu)：真空(kong)(kong)(kong)包裝不(bu)(bu)(bu)能抑制(zhi)(zhi)厭氧(yang)(yang)(yang)(yang)(yang)(yang)菌(jun)的(de)(de)(de)繁(fan)(fan)(fan)殖(zhi)(zhi)和(he)(he)酶反應引起的(de)(de)(de)食(shi)(shi)品(pin)變(bian)(bian)(bian)質和(he)(he)變(bian)(bian)(bian)色(se)(se)，因此(ci)還需與其它輔(fu)助(zhu)方法結(jie)合，如冷藏、速凍、脫(tuo)水、高溫(wen)殺菌(jun)、輻照 滅(mie)菌(jun)、微(wei)波殺菌(jun)、鹽腌(a)制(zhi)(zhi)等。）真空(kong)(kong)(kong)除(chu)氧(yang)(yang)(yang)(yang)(yang)(yang)除(chu)了抑制(zhi)(zhi)微(wei)生(sheng)(sheng)物的(de)(de)(de)生(sheng)(sheng)長(chang)(chang)和(he)(he)繁(fan)(fan)(fan)殖(zhi)(zhi)外，另一個重(zhong)要功能是(shi)防(fang)止(zhi)(zhi)食(shi)(shi)品(pin)氧(yang)(yang)(yang)(yang)(yang)(yang)化，因油(you)脂類食(shi)(shi)品(pin)中含有(you)大量不(bu)(bu)(bu)飽和(he)(he)脂肪酸，受氧(yang)(yang)(yang)(yang)(yang)(yang)的(de)(de)(de)作(zuo)用而(er)氧(yang)(yang)(yang)(yang)(yang)(yang)化，使(shi)(shi)食(shi)(shi)品(pin)變(bian)(bian)(bian)味(wei)、變(bian)(bian)(bian)質，此(ci)外，氧(yang)(yang)(yang)(yang)(yang)(yang)化還使(shi)(shi)維(wei)生(sheng)(sheng)素A和(he)(he)C損失，食(shi)(shi)品(pin)色(se)(se)素中的(de)(de)(de)不(bu)(bu)(bu)穩定物質受氧(yang)(yang)(yang)(yang)(yang)(yang)的(de)(de)(de)作(zuo)用，使(shi)(shi)顏(yan)色(se)(se)變(bian)(bian)(bian)暗(an)。所以，除(chu)氧(yang)(yang)(yang)(yang)(yang)(yang)能有(you)效地(di)防(fang)止(zhi)(zhi)食(shi)(shi)品(pin)變(bian)(bian)(bian)質，保持其色(se)(se)、香(xiang)、味(wei)及營(ying)養價值(zhi)。