真(zhen)空(kong)袋(dai)(dai)的(de)主要作用(yong)(yong)是除(chu)氧(yang)(yang)(yang)(yang)，以(yi)有(you)(you)利于防(fang)(fang)止(zhi)食(shi)(shi)(shi)品(pin)變(bian)質(zhi)，其原理(li)也(ye)比較簡單，因(yin)食(shi)(shi)(shi)品(pin)霉腐變(bian)質(zhi)主要由微(wei)(wei)(wei)生(sheng)(sheng)(sheng)物(wu)(wu)(wu)的(de)活(huo)動造(zao)成(cheng)，而(er)大(da)多數(shu)微(wei)(wei)(wei)生(sheng)(sheng)(sheng)物(wu)(wu)(wu)（如霉菌(jun)(jun)和(he)酵母菌(jun)(jun)）的(de)生(sheng)(sheng)(sheng)存是需要氧(yang)(yang)(yang)(yang)氣的(de)，而(er)真(zhen)空(kong)包裝(zhuang)(zhuang)(zhuang)就是運用(yong)(yong)這個原理(li)，把包裝(zhuang)(zhuang)(zhuang)袋(dai)(dai)內和(he)食(shi)(shi)(shi)品(pin)細胞(bao)內的(de)氧(yang)(yang)(yang)(yang)氣抽掉，使(shi)微(wei)(wei)(wei)物(wu)(wu)(wu)物(wu)(wu)(wu)失去“生(sheng)(sheng)(sheng)存的(de)環(huan)境”。實驗(yan)證明：當包裝(zhuang)(zhuang)(zhuang)袋(dai)(dai)內的(de)氧(yang)(yang)(yang)(yang)氣濃度≤1%時，微(wei)(wei)(wei)生(sheng)(sheng)(sheng)物(wu)(wu)(wu)的(de)生(sheng)(sheng)(sheng)長和(he)繁(fan)(fan)殖(zhi)速(su)度就急劇下(xia)降，氧(yang)(yang)(yang)(yang)氣濃度≤0.5%時，大(da)多數(shu)微(wei)(wei)(wei)生(sheng)(sheng)(sheng)物(wu)(wu)(wu)將(jiang)受到抑(yi)制(zhi)而(er)停止(zhi)繁(fan)(fan)殖(zhi)。（注：真(zhen)空(kong)包裝(zhuang)(zhuang)(zhuang)不(bu)能抑(yi)制(zhi)厭氧(yang)(yang)(yang)(yang)菌(jun)(jun)的(de)繁(fan)(fan)殖(zhi)和(he)酶反應(ying)引起(qi)的(de)食(shi)(shi)(shi)品(pin)變(bian)質(zhi)和(he)變(bian)色(se)(se)，因(yin)此還需與其它輔助方法結合，如冷藏、速(su)凍、脫(tuo)水、高溫殺菌(jun)(jun)、輻(fu)照(zhao) 滅菌(jun)(jun)、微(wei)(wei)(wei)波殺菌(jun)(jun)、鹽(yan)腌制(zhi)等(deng)。）真(zhen)空(kong)除(chu)氧(yang)(yang)(yang)(yang)除(chu)了抑(yi)制(zhi)微(wei)(wei)(wei)生(sheng)(sheng)(sheng)物(wu)(wu)(wu)的(de)生(sheng)(sheng)(sheng)長和(he)繁(fan)(fan)殖(zhi)外(wai)，另一個重要功能是防(fang)(fang)止(zhi)食(shi)(shi)(shi)品(pin)氧(yang)(yang)(yang)(yang)化(hua)，因(yin)油脂(zhi)類食(shi)(shi)(shi)品(pin)中(zhong)(zhong)含有(you)(you)大(da)量不(bu)飽(bao)和(he)脂(zhi)肪酸(suan)，受氧(yang)(yang)(yang)(yang)的(de)作用(yong)(yong)而(er)氧(yang)(yang)(yang)(yang)化(hua)，使(shi)食(shi)(shi)(shi)品(pin)變(bian)味、變(bian)質(zhi)，此外(wai)，氧(yang)(yang)(yang)(yang)化(hua)還使(shi)維生(sheng)(sheng)(sheng)素(su)A和(he)C損失，食(shi)(shi)(shi)品(pin)色(se)(se)素(su)中(zhong)(zhong)的(de)不(bu)穩定物(wu)(wu)(wu)質(zhi)受氧(yang)(yang)(yang)(yang)的(de)作用(yong)(yong)，使(shi)顏色(se)(se)變(bian)暗。所以(yi)，除(chu)氧(yang)(yang)(yang)(yang)能有(you)(you)效地防(fang)(fang)止(zhi)食(shi)(shi)(shi)品(pin)變(bian)質(zhi)，保(bao)持其色(se)(se)、香、味及營(ying)養價值。