真空(kong)袋的(de)主要(yao)作用(yong)是(shi)除氧(yang)(yang)(yang)(yang)(yang)，以(yi)有利于防止(zhi)食(shi)(shi)品(pin)(pin)(pin)變(bian)質(zhi)(zhi)(zhi)，其(qi)原(yuan)理(li)(li)也比較簡單，因食(shi)(shi)品(pin)(pin)(pin)霉(mei)腐變(bian)質(zhi)(zhi)(zhi)主要(yao)由微(wei)生(sheng)(sheng)(sheng)物(wu)的(de)活動造(zao)成，而(er)大(da)多數(shu)微(wei)生(sheng)(sheng)(sheng)物(wu)（如霉(mei)菌(jun)和(he)酵母菌(jun)）的(de)生(sheng)(sheng)(sheng)存是(shi)需要(yao)氧(yang)(yang)(yang)(yang)(yang)氣(qi)的(de)，而(er)真空(kong)包(bao)裝(zhuang)就是(shi)運用(yong)這個原(yuan)理(li)(li)，把(ba)包(bao)裝(zhuang)袋內(nei)和(he)食(shi)(shi)品(pin)(pin)(pin)細胞(bao)內(nei)的(de)氧(yang)(yang)(yang)(yang)(yang)氣(qi)抽掉，使(shi)微(wei)物(wu)物(wu)失(shi)去“生(sheng)(sheng)(sheng)存的(de)環(huan)境”。實驗證明(ming)：當包(bao)裝(zhuang)袋內(nei)的(de)氧(yang)(yang)(yang)(yang)(yang)氣(qi)濃(nong)度≤1%時，微(wei)生(sheng)(sheng)(sheng)物(wu)的(de)生(sheng)(sheng)(sheng)長和(he)繁(fan)殖速(su)度就急劇(ju)下降(jiang)，氧(yang)(yang)(yang)(yang)(yang)氣(qi)濃(nong)度≤0.5%時，大(da)多數(shu)微(wei)生(sheng)(sheng)(sheng)物(wu)將受到抑(yi)(yi)制而(er)停止(zhi)繁(fan)殖。（注：真空(kong)包(bao)裝(zhuang)不能(neng)抑(yi)(yi)制厭氧(yang)(yang)(yang)(yang)(yang)菌(jun)的(de)繁(fan)殖和(he)酶反應(ying)引起的(de)食(shi)(shi)品(pin)(pin)(pin)變(bian)質(zhi)(zhi)(zhi)和(he)變(bian)色，因此(ci)還(huan)(huan)需與其(qi)它輔助方法結合，如冷(leng)藏、速(su)凍、脫水、高溫(wen)殺菌(jun)、輻照(zhao) 滅菌(jun)、微(wei)波殺菌(jun)、鹽腌制等。）真空(kong)除氧(yang)(yang)(yang)(yang)(yang)除了抑(yi)(yi)制微(wei)生(sheng)(sheng)(sheng)物(wu)的(de)生(sheng)(sheng)(sheng)長和(he)繁(fan)殖外，另一(yi)個重要(yao)功能(neng)是(shi)防止(zhi)食(shi)(shi)品(pin)(pin)(pin)氧(yang)(yang)(yang)(yang)(yang)化，因油脂(zhi)類食(shi)(shi)品(pin)(pin)(pin)中含有大(da)量不飽和(he)脂(zhi)肪(fang)酸，受氧(yang)(yang)(yang)(yang)(yang)的(de)作用(yong)而(er)氧(yang)(yang)(yang)(yang)(yang)化，使(shi)食(shi)(shi)品(pin)(pin)(pin)變(bian)味(wei)、變(bian)質(zhi)(zhi)(zhi)，此(ci)外，氧(yang)(yang)(yang)(yang)(yang)化還(huan)(huan)使(shi)維生(sheng)(sheng)(sheng)素(su)A和(he)C損失(shi)，食(shi)(shi)品(pin)(pin)(pin)色素(su)中的(de)不穩定(ding)物(wu)質(zhi)(zhi)(zhi)受氧(yang)(yang)(yang)(yang)(yang)的(de)作用(yong)，使(shi)顏色變(bian)暗。所以(yi)，除氧(yang)(yang)(yang)(yang)(yang)能(neng)有效地防止(zhi)食(shi)(shi)品(pin)(pin)(pin)變(bian)質(zhi)(zhi)(zhi)，保持其(qi)色、香、味(wei)及營養價值(zhi)。