真(zhen)(zhen)空袋(dai)的(de)主要作(zuo)用是除(chu)(chu)氧(yang)，以有(you)(you)利(li)于防(fang)(fang)止(zhi)(zhi)(zhi)食(shi)(shi)(shi)品(pin)(pin)變(bian)質(zhi)(zhi)(zhi)(zhi)(zhi)，其原理(li)也比較簡單，因食(shi)(shi)(shi)品(pin)(pin)霉腐變(bian)質(zhi)(zhi)(zhi)(zhi)(zhi)主要由微(wei)(wei)生(sheng)(sheng)(sheng)(sheng)(sheng)物(wu)(wu)(wu)的(de)活(huo)動(dong)造成，而大多數(shu)(shu)微(wei)(wei)生(sheng)(sheng)(sheng)(sheng)(sheng)物(wu)(wu)(wu)（如霉菌和(he)(he)酵母菌）的(de)生(sheng)(sheng)(sheng)(sheng)(sheng)存是需(xu)要氧(yang)氣(qi)的(de)，而真(zhen)(zhen)空包裝(zhuang)就是運用這(zhe)個(ge)原理(li)，把包裝(zhuang)袋(dai)內(nei)(nei)和(he)(he)食(shi)(shi)(shi)品(pin)(pin)細胞內(nei)(nei)的(de)氧(yang)氣(qi)抽(chou)掉，使(shi)(shi)(shi)微(wei)(wei)物(wu)(wu)(wu)物(wu)(wu)(wu)失去(qu)“生(sheng)(sheng)(sheng)(sheng)(sheng)存的(de)環(huan)境(jing)”。實驗證明：當包裝(zhuang)袋(dai)內(nei)(nei)的(de)氧(yang)氣(qi)濃度(du)≤1%時(shi)，微(wei)(wei)生(sheng)(sheng)(sheng)(sheng)(sheng)物(wu)(wu)(wu)的(de)生(sheng)(sheng)(sheng)(sheng)(sheng)長和(he)(he)繁(fan)殖(zhi)速度(du)就急劇(ju)下降，氧(yang)氣(qi)濃度(du)≤0.5%時(shi)，大多數(shu)(shu)微(wei)(wei)生(sheng)(sheng)(sheng)(sheng)(sheng)物(wu)(wu)(wu)將受到抑(yi)(yi)制而停止(zhi)(zhi)(zhi)繁(fan)殖(zhi)。（注(zhu)：真(zhen)(zhen)空包裝(zhuang)不能(neng)(neng)抑(yi)(yi)制厭氧(yang)菌的(de)繁(fan)殖(zhi)和(he)(he)酶反(fan)應引起的(de)食(shi)(shi)(shi)品(pin)(pin)變(bian)質(zhi)(zhi)(zhi)(zhi)(zhi)和(he)(he)變(bian)色，因此還需(xu)與其它輔助(zhu)方法結合，如冷藏(zang)、速凍、脫(tuo)水、高(gao)溫殺(sha)菌、輻照(zhao) 滅(mie)菌、微(wei)(wei)波殺(sha)菌、鹽腌制等(deng)。）真(zhen)(zhen)空除(chu)(chu)氧(yang)除(chu)(chu)了(le)抑(yi)(yi)制微(wei)(wei)生(sheng)(sheng)(sheng)(sheng)(sheng)物(wu)(wu)(wu)的(de)生(sheng)(sheng)(sheng)(sheng)(sheng)長和(he)(he)繁(fan)殖(zhi)外(wai)，另一(yi)個(ge)重要功(gong)能(neng)(neng)是防(fang)(fang)止(zhi)(zhi)(zhi)食(shi)(shi)(shi)品(pin)(pin)氧(yang)化(hua)，因油脂類食(shi)(shi)(shi)品(pin)(pin)中含有(you)(you)大量不飽和(he)(he)脂肪酸，受氧(yang)的(de)作(zuo)用而氧(yang)化(hua)，使(shi)(shi)(shi)食(shi)(shi)(shi)品(pin)(pin)變(bian)味(wei)(wei)、變(bian)質(zhi)(zhi)(zhi)(zhi)(zhi)，此外(wai)，氧(yang)化(hua)還使(shi)(shi)(shi)維生(sheng)(sheng)(sheng)(sheng)(sheng)素(su)A和(he)(he)C損失，食(shi)(shi)(shi)品(pin)(pin)色素(su)中的(de)不穩定物(wu)(wu)(wu)質(zhi)(zhi)(zhi)(zhi)(zhi)受氧(yang)的(de)作(zuo)用，使(shi)(shi)(shi)顏色變(bian)暗。所以，除(chu)(chu)氧(yang)能(neng)(neng)有(you)(you)效地(di)防(fang)(fang)止(zhi)(zhi)(zhi)食(shi)(shi)(shi)品(pin)(pin)變(bian)質(zhi)(zhi)(zhi)(zhi)(zhi)，保持其色、香、味(wei)(wei)及(ji)營養價值。