真(zhen)空袋(dai)的(de)(de)(de)主要(yao)作用(yong)(yong)是(shi)(shi)除(chu)氧(yang)(yang)(yang)(yang)，以(yi)有利(li)于防(fang)止(zhi)食(shi)(shi)(shi)(shi)品(pin)(pin)(pin)變質(zhi)(zhi)，其原理(li)也(ye)比較簡單，因食(shi)(shi)(shi)(shi)品(pin)(pin)(pin)霉腐(fu)變質(zhi)(zhi)主要(yao)由微(wei)生(sheng)(sheng)(sheng)物(wu)(wu)(wu)(wu)(wu)的(de)(de)(de)活動造(zao)成，而(er)(er)大多(duo)數(shu)微(wei)生(sheng)(sheng)(sheng)物(wu)(wu)(wu)(wu)(wu)（如霉菌(jun)和(he)酵母(mu)菌(jun)）的(de)(de)(de)生(sheng)(sheng)(sheng)存(cun)(cun)是(shi)(shi)需要(yao)氧(yang)(yang)(yang)(yang)氣(qi)(qi)的(de)(de)(de)，而(er)(er)真(zhen)空包(bao)裝就是(shi)(shi)運用(yong)(yong)這個原理(li)，把包(bao)裝袋(dai)內和(he)食(shi)(shi)(shi)(shi)品(pin)(pin)(pin)細胞內的(de)(de)(de)氧(yang)(yang)(yang)(yang)氣(qi)(qi)抽掉，使(shi)(shi)微(wei)物(wu)(wu)(wu)(wu)(wu)物(wu)(wu)(wu)(wu)(wu)失去“生(sheng)(sheng)(sheng)存(cun)(cun)的(de)(de)(de)環(huan)境”。實(shi)驗證明(ming)：當包(bao)裝袋(dai)內的(de)(de)(de)氧(yang)(yang)(yang)(yang)氣(qi)(qi)濃度(du)(du)≤1%時，微(wei)生(sheng)(sheng)(sheng)物(wu)(wu)(wu)(wu)(wu)的(de)(de)(de)生(sheng)(sheng)(sheng)長和(he)繁(fan)殖(zhi)速度(du)(du)就急劇下降，氧(yang)(yang)(yang)(yang)氣(qi)(qi)濃度(du)(du)≤0.5%時，大多(duo)數(shu)微(wei)生(sheng)(sheng)(sheng)物(wu)(wu)(wu)(wu)(wu)將受(shou)到抑(yi)制(zhi)而(er)(er)停止(zhi)繁(fan)殖(zhi)。（注：真(zhen)空包(bao)裝不能(neng)抑(yi)制(zhi)厭氧(yang)(yang)(yang)(yang)菌(jun)的(de)(de)(de)繁(fan)殖(zhi)和(he)酶反應引起(qi)的(de)(de)(de)食(shi)(shi)(shi)(shi)品(pin)(pin)(pin)變質(zhi)(zhi)和(he)變色(se)，因此還需與其它輔(fu)助方(fang)法(fa)結合，如冷(leng)藏(zang)、速凍(dong)、脫水(shui)、高溫殺菌(jun)、輻照 滅菌(jun)、微(wei)波殺菌(jun)、鹽腌制(zhi)等。）真(zhen)空除(chu)氧(yang)(yang)(yang)(yang)除(chu)了(le)抑(yi)制(zhi)微(wei)生(sheng)(sheng)(sheng)物(wu)(wu)(wu)(wu)(wu)的(de)(de)(de)生(sheng)(sheng)(sheng)長和(he)繁(fan)殖(zhi)外，另一個重要(yao)功能(neng)是(shi)(shi)防(fang)止(zhi)食(shi)(shi)(shi)(shi)品(pin)(pin)(pin)氧(yang)(yang)(yang)(yang)化，因油脂類食(shi)(shi)(shi)(shi)品(pin)(pin)(pin)中(zhong)含有大量不飽和(he)脂肪酸，受(shou)氧(yang)(yang)(yang)(yang)的(de)(de)(de)作用(yong)(yong)而(er)(er)氧(yang)(yang)(yang)(yang)化，使(shi)(shi)食(shi)(shi)(shi)(shi)品(pin)(pin)(pin)變味、變質(zhi)(zhi)，此外，氧(yang)(yang)(yang)(yang)化還使(shi)(shi)維生(sheng)(sheng)(sheng)素A和(he)C損失，食(shi)(shi)(shi)(shi)品(pin)(pin)(pin)色(se)素中(zhong)的(de)(de)(de)不穩定物(wu)(wu)(wu)(wu)(wu)質(zhi)(zhi)受(shou)氧(yang)(yang)(yang)(yang)的(de)(de)(de)作用(yong)(yong)，使(shi)(shi)顏色(se)變暗。所以(yi)，除(chu)氧(yang)(yang)(yang)(yang)能(neng)有效地防(fang)止(zhi)食(shi)(shi)(shi)(shi)品(pin)(pin)(pin)變質(zhi)(zhi)，保持其色(se)、香、味及營養價(jia)值。