真(zhen)空袋的(de)(de)(de)主要(yao)作(zuo)用(yong)是(shi)除氧(yang)，以有利(li)于防(fang)止食(shi)(shi)(shi)品(pin)變(bian)(bian)(bian)(bian)質(zhi)(zhi)，其原理也比(bi)較(jiao)簡單，因食(shi)(shi)(shi)品(pin)霉腐(fu)變(bian)(bian)(bian)(bian)質(zhi)(zhi)主要(yao)由微(wei)(wei)生(sheng)(sheng)(sheng)物(wu)(wu)的(de)(de)(de)活動造(zao)成，而(er)大多數微(wei)(wei)生(sheng)(sheng)(sheng)物(wu)(wu)（如(ru)霉菌和(he)(he)酵母(mu)菌）的(de)(de)(de)生(sheng)(sheng)(sheng)存是(shi)需要(yao)氧(yang)氣(qi)的(de)(de)(de)，而(er)真(zhen)空包(bao)裝(zhuang)(zhuang)就是(shi)運用(yong)這(zhe)個(ge)原理，把包(bao)裝(zhuang)(zhuang)袋內和(he)(he)食(shi)(shi)(shi)品(pin)細胞(bao)內的(de)(de)(de)氧(yang)氣(qi)抽掉，使微(wei)(wei)物(wu)(wu)物(wu)(wu)失去“生(sheng)(sheng)(sheng)存的(de)(de)(de)環境(jing)”。實驗證(zheng)明：當包(bao)裝(zhuang)(zhuang)袋內的(de)(de)(de)氧(yang)氣(qi)濃度≤1%時，微(wei)(wei)生(sheng)(sheng)(sheng)物(wu)(wu)的(de)(de)(de)生(sheng)(sheng)(sheng)長和(he)(he)繁殖(zhi)(zhi)速(su)度就急劇下降(jiang)，氧(yang)氣(qi)濃度≤0.5%時，大多數微(wei)(wei)生(sheng)(sheng)(sheng)物(wu)(wu)將受(shou)到(dao)抑(yi)制(zhi)而(er)停(ting)止繁殖(zhi)(zhi)。（注：真(zhen)空包(bao)裝(zhuang)(zhuang)不能(neng)(neng)抑(yi)制(zhi)厭氧(yang)菌的(de)(de)(de)繁殖(zhi)(zhi)和(he)(he)酶反應引起的(de)(de)(de)食(shi)(shi)(shi)品(pin)變(bian)(bian)(bian)(bian)質(zhi)(zhi)和(he)(he)變(bian)(bian)(bian)(bian)色(se)，因此還需與其它輔(fu)助方(fang)法(fa)結合，如(ru)冷藏、速(su)凍、脫水、高溫殺菌、輻照 滅菌、微(wei)(wei)波(bo)殺菌、鹽腌(a)制(zhi)等。）真(zhen)空除氧(yang)除了抑(yi)制(zhi)微(wei)(wei)生(sheng)(sheng)(sheng)物(wu)(wu)的(de)(de)(de)生(sheng)(sheng)(sheng)長和(he)(he)繁殖(zhi)(zhi)外，另一個(ge)重要(yao)功(gong)能(neng)(neng)是(shi)防(fang)止食(shi)(shi)(shi)品(pin)氧(yang)化(hua)，因油脂類食(shi)(shi)(shi)品(pin)中(zhong)含(han)有大量不飽(bao)和(he)(he)脂肪酸(suan)，受(shou)氧(yang)的(de)(de)(de)作(zuo)用(yong)而(er)氧(yang)化(hua)，使食(shi)(shi)(shi)品(pin)變(bian)(bian)(bian)(bian)味(wei)、變(bian)(bian)(bian)(bian)質(zhi)(zhi)，此外，氧(yang)化(hua)還使維生(sheng)(sheng)(sheng)素A和(he)(he)C損(sun)失，食(shi)(shi)(shi)品(pin)色(se)素中(zhong)的(de)(de)(de)不穩定物(wu)(wu)質(zhi)(zhi)受(shou)氧(yang)的(de)(de)(de)作(zuo)用(yong)，使顏色(se)變(bian)(bian)(bian)(bian)暗。所以，除氧(yang)能(neng)(neng)有效地防(fang)止食(shi)(shi)(shi)品(pin)變(bian)(bian)(bian)(bian)質(zhi)(zhi)，保持(chi)其色(se)、香、味(wei)及營養價值。