真(zhen)空袋(dai)的(de)(de)(de)主(zhu)要(yao)作(zuo)用是(shi)(shi)除(chu)氧(yang)(yang)(yang)(yang)(yang)，以有利于防(fang)(fang)止(zhi)食(shi)(shi)(shi)品(pin)(pin)變(bian)質(zhi)，其原(yuan)(yuan)理也比較簡(jian)單，因食(shi)(shi)(shi)品(pin)(pin)霉腐變(bian)質(zhi)主(zhu)要(yao)由微(wei)(wei)(wei)生(sheng)(sheng)物的(de)(de)(de)活動造成，而(er)大多數(shu)微(wei)(wei)(wei)生(sheng)(sheng)物（如(ru)霉菌(jun)(jun)和(he)(he)酵母(mu)菌(jun)(jun)）的(de)(de)(de)生(sheng)(sheng)存(cun)是(shi)(shi)需要(yao)氧(yang)(yang)(yang)(yang)(yang)氣的(de)(de)(de)，而(er)真(zhen)空包(bao)裝就(jiu)是(shi)(shi)運用這個原(yuan)(yuan)理，把包(bao)裝袋(dai)內和(he)(he)食(shi)(shi)(shi)品(pin)(pin)細胞(bao)內的(de)(de)(de)氧(yang)(yang)(yang)(yang)(yang)氣抽掉，使(shi)微(wei)(wei)(wei)物物失去“生(sheng)(sheng)存(cun)的(de)(de)(de)環境”。實驗證明：當包(bao)裝袋(dai)內的(de)(de)(de)氧(yang)(yang)(yang)(yang)(yang)氣濃度≤1%時，微(wei)(wei)(wei)生(sheng)(sheng)物的(de)(de)(de)生(sheng)(sheng)長和(he)(he)繁(fan)(fan)(fan)殖(zhi)(zhi)(zhi)速(su)度就(jiu)急劇下(xia)降，氧(yang)(yang)(yang)(yang)(yang)氣濃度≤0.5%時，大多數(shu)微(wei)(wei)(wei)生(sheng)(sheng)物將受到抑(yi)(yi)制(zhi)而(er)停(ting)止(zhi)繁(fan)(fan)(fan)殖(zhi)(zhi)(zhi)。（注：真(zhen)空包(bao)裝不(bu)能(neng)抑(yi)(yi)制(zhi)厭氧(yang)(yang)(yang)(yang)(yang)菌(jun)(jun)的(de)(de)(de)繁(fan)(fan)(fan)殖(zhi)(zhi)(zhi)和(he)(he)酶反應引(yin)起的(de)(de)(de)食(shi)(shi)(shi)品(pin)(pin)變(bian)質(zhi)和(he)(he)變(bian)色(se)，因此(ci)還需與其它輔助方法(fa)結合，如(ru)冷藏、速(su)凍、脫水、高(gao)溫殺菌(jun)(jun)、輻照(zhao) 滅菌(jun)(jun)、微(wei)(wei)(wei)波(bo)殺菌(jun)(jun)、鹽腌制(zhi)等(deng)。）真(zhen)空除(chu)氧(yang)(yang)(yang)(yang)(yang)除(chu)了抑(yi)(yi)制(zhi)微(wei)(wei)(wei)生(sheng)(sheng)物的(de)(de)(de)生(sheng)(sheng)長和(he)(he)繁(fan)(fan)(fan)殖(zhi)(zhi)(zhi)外，另一(yi)個重要(yao)功能(neng)是(shi)(shi)防(fang)(fang)止(zhi)食(shi)(shi)(shi)品(pin)(pin)氧(yang)(yang)(yang)(yang)(yang)化，因油(you)脂(zhi)類食(shi)(shi)(shi)品(pin)(pin)中含有大量不(bu)飽和(he)(he)脂(zhi)肪(fang)酸，受氧(yang)(yang)(yang)(yang)(yang)的(de)(de)(de)作(zuo)用而(er)氧(yang)(yang)(yang)(yang)(yang)化，使(shi)食(shi)(shi)(shi)品(pin)(pin)變(bian)味、變(bian)質(zhi)，此(ci)外，氧(yang)(yang)(yang)(yang)(yang)化還使(shi)維生(sheng)(sheng)素A和(he)(he)C損失，食(shi)(shi)(shi)品(pin)(pin)色(se)素中的(de)(de)(de)不(bu)穩定物質(zhi)受氧(yang)(yang)(yang)(yang)(yang)的(de)(de)(de)作(zuo)用，使(shi)顏色(se)變(bian)暗。所以，除(chu)氧(yang)(yang)(yang)(yang)(yang)能(neng)有效地防(fang)(fang)止(zhi)食(shi)(shi)(shi)品(pin)(pin)變(bian)質(zhi)，保持其色(se)、香、味及(ji)營養(yang)價值。