真(zhen)空袋(dai)的(de)(de)(de)(de)主要(yao)作用(yong)是(shi)(shi)除(chu)氧(yang)(yang)(yang)，以有(you)利于防止(zhi)食(shi)品(pin)(pin)(pin)變(bian)質(zhi)(zhi)，其(qi)原(yuan)理(li)也比較簡單，因食(shi)品(pin)(pin)(pin)霉腐(fu)變(bian)質(zhi)(zhi)主要(yao)由微(wei)(wei)(wei)(wei)(wei)生(sheng)(sheng)(sheng)物的(de)(de)(de)(de)活動造成，而(er)大多(duo)數微(wei)(wei)(wei)(wei)(wei)生(sheng)(sheng)(sheng)物（如霉菌(jun)(jun)和(he)酵母菌(jun)(jun)）的(de)(de)(de)(de)生(sheng)(sheng)(sheng)存是(shi)(shi)需(xu)要(yao)氧(yang)(yang)(yang)氣(qi)(qi)的(de)(de)(de)(de)，而(er)真(zhen)空包裝就是(shi)(shi)運用(yong)這個(ge)原(yuan)理(li)，把包裝袋(dai)內(nei)(nei)和(he)食(shi)品(pin)(pin)(pin)細胞內(nei)(nei)的(de)(de)(de)(de)氧(yang)(yang)(yang)氣(qi)(qi)抽掉，使(shi)微(wei)(wei)(wei)(wei)(wei)物物失去“生(sheng)(sheng)(sheng)存的(de)(de)(de)(de)環境(jing)”。實驗(yan)證(zheng)明：當包裝袋(dai)內(nei)(nei)的(de)(de)(de)(de)氧(yang)(yang)(yang)氣(qi)(qi)濃度(du)≤1%時(shi)，微(wei)(wei)(wei)(wei)(wei)生(sheng)(sheng)(sheng)物的(de)(de)(de)(de)生(sheng)(sheng)(sheng)長(chang)和(he)繁殖(zhi)速度(du)就急劇(ju)下降(jiang)，氧(yang)(yang)(yang)氣(qi)(qi)濃度(du)≤0.5%時(shi)，大多(duo)數微(wei)(wei)(wei)(wei)(wei)生(sheng)(sheng)(sheng)物將受(shou)到抑(yi)制而(er)停(ting)止(zhi)繁殖(zhi)。（注：真(zhen)空包裝不能(neng)(neng)抑(yi)制厭氧(yang)(yang)(yang)菌(jun)(jun)的(de)(de)(de)(de)繁殖(zhi)和(he)酶(mei)反應引起(qi)的(de)(de)(de)(de)食(shi)品(pin)(pin)(pin)變(bian)質(zhi)(zhi)和(he)變(bian)色，因此還需(xu)與(yu)其(qi)它(ta)輔助(zhu)方(fang)法(fa)結合，如冷藏、速凍、脫水、高溫殺菌(jun)(jun)、輻照 滅菌(jun)(jun)、微(wei)(wei)(wei)(wei)(wei)波殺菌(jun)(jun)、鹽腌制等(deng)。）真(zhen)空除(chu)氧(yang)(yang)(yang)除(chu)了抑(yi)制微(wei)(wei)(wei)(wei)(wei)生(sheng)(sheng)(sheng)物的(de)(de)(de)(de)生(sheng)(sheng)(sheng)長(chang)和(he)繁殖(zhi)外(wai)，另一個(ge)重要(yao)功能(neng)(neng)是(shi)(shi)防止(zhi)食(shi)品(pin)(pin)(pin)氧(yang)(yang)(yang)化(hua)，因油脂(zhi)(zhi)類食(shi)品(pin)(pin)(pin)中(zhong)含有(you)大量不飽(bao)和(he)脂(zhi)(zhi)肪(fang)酸，受(shou)氧(yang)(yang)(yang)的(de)(de)(de)(de)作用(yong)而(er)氧(yang)(yang)(yang)化(hua)，使(shi)食(shi)品(pin)(pin)(pin)變(bian)味、變(bian)質(zhi)(zhi)，此外(wai)，氧(yang)(yang)(yang)化(hua)還使(shi)維生(sheng)(sheng)(sheng)素A和(he)C損失，食(shi)品(pin)(pin)(pin)色素中(zhong)的(de)(de)(de)(de)不穩定物質(zhi)(zhi)受(shou)氧(yang)(yang)(yang)的(de)(de)(de)(de)作用(yong)，使(shi)顏(yan)色變(bian)暗。所(suo)以，除(chu)氧(yang)(yang)(yang)能(neng)(neng)有(you)效地(di)防止(zhi)食(shi)品(pin)(pin)(pin)變(bian)質(zhi)(zhi)，保(bao)持其(qi)色、香(xiang)、味及(ji)營養價值。