真(zhen)(zhen)空袋(dai)的(de)主要(yao)(yao)作用(yong)是(shi)(shi)除氧(yang)(yang)，以有(you)利(li)于防止(zhi)(zhi)(zhi)食(shi)品(pin)變(bian)(bian)質(zhi)(zhi)，其原理也比較簡單，因食(shi)品(pin)霉腐變(bian)(bian)質(zhi)(zhi)主要(yao)(yao)由(you)微(wei)(wei)生(sheng)(sheng)(sheng)物(wu)的(de)活動造成(cheng)，而(er)(er)大(da)多(duo)數微(wei)(wei)生(sheng)(sheng)(sheng)物(wu)（如(ru)霉菌和(he)(he)(he)酵母(mu)菌）的(de)生(sheng)(sheng)(sheng)存是(shi)(shi)需(xu)要(yao)(yao)氧(yang)(yang)氣(qi)的(de)，而(er)(er)真(zhen)(zhen)空包(bao)裝(zhuang)(zhuang)就是(shi)(shi)運用(yong)這(zhe)個(ge)原理，把包(bao)裝(zhuang)(zhuang)袋(dai)內和(he)(he)(he)食(shi)品(pin)細胞內的(de)氧(yang)(yang)氣(qi)抽掉，使(shi)微(wei)(wei)物(wu)物(wu)失(shi)去“生(sheng)(sheng)(sheng)存的(de)環(huan)境”。實驗證(zheng)明：當(dang)包(bao)裝(zhuang)(zhuang)袋(dai)內的(de)氧(yang)(yang)氣(qi)濃度(du)≤1%時，微(wei)(wei)生(sheng)(sheng)(sheng)物(wu)的(de)生(sheng)(sheng)(sheng)長和(he)(he)(he)繁(fan)殖(zhi)速度(du)就急劇下降，氧(yang)(yang)氣(qi)濃度(du)≤0.5%時，大(da)多(duo)數微(wei)(wei)生(sheng)(sheng)(sheng)物(wu)將(jiang)受到抑制(zhi)而(er)(er)停止(zhi)(zhi)(zhi)繁(fan)殖(zhi)。（注：真(zhen)(zhen)空包(bao)裝(zhuang)(zhuang)不能(neng)抑制(zhi)厭(yan)氧(yang)(yang)菌的(de)繁(fan)殖(zhi)和(he)(he)(he)酶(mei)反應引起的(de)食(shi)品(pin)變(bian)(bian)質(zhi)(zhi)和(he)(he)(he)變(bian)(bian)色(se)，因此還需(xu)與(yu)其它輔助方法結合，如(ru)冷藏、速凍、脫水、高溫(wen)殺(sha)菌、輻照 滅菌、微(wei)(wei)波(bo)殺(sha)菌、鹽腌制(zhi)等。）真(zhen)(zhen)空除氧(yang)(yang)除了抑制(zhi)微(wei)(wei)生(sheng)(sheng)(sheng)物(wu)的(de)生(sheng)(sheng)(sheng)長和(he)(he)(he)繁(fan)殖(zhi)外，另(ling)一個(ge)重要(yao)(yao)功(gong)能(neng)是(shi)(shi)防止(zhi)(zhi)(zhi)食(shi)品(pin)氧(yang)(yang)化，因油脂類(lei)食(shi)品(pin)中(zhong)含有(you)大(da)量不飽和(he)(he)(he)脂肪酸，受氧(yang)(yang)的(de)作用(yong)而(er)(er)氧(yang)(yang)化，使(shi)食(shi)品(pin)變(bian)(bian)味、變(bian)(bian)質(zhi)(zhi)，此外，氧(yang)(yang)化還使(shi)維生(sheng)(sheng)(sheng)素A和(he)(he)(he)C損失(shi)，食(shi)品(pin)色(se)素中(zhong)的(de)不穩定物(wu)質(zhi)(zhi)受氧(yang)(yang)的(de)作用(yong)，使(shi)顏色(se)變(bian)(bian)暗。所(suo)以，除氧(yang)(yang)能(neng)有(you)效地防止(zhi)(zhi)(zhi)食(shi)品(pin)變(bian)(bian)質(zhi)(zhi)，保持其色(se)、香、味及營養(yang)價(jia)值。