真(zhen)空(kong)袋的(de)(de)(de)主要作用是除(chu)(chu)氧(yang)(yang)(yang)，以有(you)利于防(fang)止(zhi)食(shi)(shi)品變(bian)(bian)質(zhi)(zhi)，其(qi)原理(li)也比較簡單，因食(shi)(shi)品霉腐變(bian)(bian)質(zhi)(zhi)主要由微(wei)生(sheng)(sheng)物(wu)的(de)(de)(de)活動造(zao)成，而(er)(er)大(da)多數微(wei)生(sheng)(sheng)物(wu)（如(ru)霉菌和酵(jiao)母菌）的(de)(de)(de)生(sheng)(sheng)存是需(xu)要氧(yang)(yang)(yang)氣(qi)(qi)(qi)(qi)的(de)(de)(de)，而(er)(er)真(zhen)空(kong)包(bao)(bao)(bao)(bao)裝(zhuang)(zhuang)就是運用這個原理(li)，把包(bao)(bao)(bao)(bao)裝(zhuang)(zhuang)袋內(nei)和食(shi)(shi)品細胞內(nei)的(de)(de)(de)氧(yang)(yang)(yang)氣(qi)(qi)(qi)(qi)抽掉，使(shi)微(wei)物(wu)物(wu)失去(qu)“生(sheng)(sheng)存的(de)(de)(de)環境”。實驗(yan)證明：當包(bao)(bao)(bao)(bao)裝(zhuang)(zhuang)袋內(nei)的(de)(de)(de)氧(yang)(yang)(yang)氣(qi)(qi)(qi)(qi)濃(nong)(nong)度≤1%時(shi)，微(wei)生(sheng)(sheng)物(wu)的(de)(de)(de)生(sheng)(sheng)長(chang)和繁(fan)殖(zhi)(zhi)速度就急劇(ju)下降，氧(yang)(yang)(yang)氣(qi)(qi)(qi)(qi)濃(nong)(nong)度≤0.5%時(shi)，大(da)多數微(wei)生(sheng)(sheng)物(wu)將受(shou)到抑(yi)制(zhi)而(er)(er)停止(zhi)繁(fan)殖(zhi)(zhi)。（注：真(zhen)空(kong)包(bao)(bao)(bao)(bao)裝(zhuang)(zhuang)不(bu)能(neng)抑(yi)制(zhi)厭(yan)氧(yang)(yang)(yang)菌的(de)(de)(de)繁(fan)殖(zhi)(zhi)和酶反應引起的(de)(de)(de)食(shi)(shi)品變(bian)(bian)質(zhi)(zhi)和變(bian)(bian)色(se)，因此還需(xu)與其(qi)它輔助方法結合，如(ru)冷藏、速凍(dong)、脫水、高溫殺菌、輻照 滅菌、微(wei)波殺菌、鹽腌制(zhi)等。）真(zhen)空(kong)除(chu)(chu)氧(yang)(yang)(yang)除(chu)(chu)了抑(yi)制(zhi)微(wei)生(sheng)(sheng)物(wu)的(de)(de)(de)生(sheng)(sheng)長(chang)和繁(fan)殖(zhi)(zhi)外(wai)，另(ling)一個重要功能(neng)是防(fang)止(zhi)食(shi)(shi)品氧(yang)(yang)(yang)化，因油脂類食(shi)(shi)品中(zhong)含(han)有(you)大(da)量(liang)不(bu)飽和脂肪(fang)酸，受(shou)氧(yang)(yang)(yang)的(de)(de)(de)作用而(er)(er)氧(yang)(yang)(yang)化，使(shi)食(shi)(shi)品變(bian)(bian)味、變(bian)(bian)質(zhi)(zhi)，此外(wai)，氧(yang)(yang)(yang)化還使(shi)維生(sheng)(sheng)素A和C損失，食(shi)(shi)品色(se)素中(zhong)的(de)(de)(de)不(bu)穩定物(wu)質(zhi)(zhi)受(shou)氧(yang)(yang)(yang)的(de)(de)(de)作用，使(shi)顏(yan)色(se)變(bian)(bian)暗。所以，除(chu)(chu)氧(yang)(yang)(yang)能(neng)有(you)效(xiao)地(di)防(fang)止(zhi)食(shi)(shi)品變(bian)(bian)質(zhi)(zhi)，保持(chi)其(qi)色(se)、香、味及(ji)營養(yang)價值。