真(zhen)(zhen)空袋的(de)(de)主要(yao)作(zuo)用是(shi)除(chu)(chu)氧(yang)(yang)(yang)(yang)(yang)，以有利于防(fang)止(zhi)食(shi)(shi)(shi)(shi)品(pin)(pin)(pin)(pin)變(bian)(bian)(bian)質(zhi)(zhi)，其原理(li)也比較簡單(dan)，因食(shi)(shi)(shi)(shi)品(pin)(pin)(pin)(pin)霉腐變(bian)(bian)(bian)質(zhi)(zhi)主要(yao)由微(wei)生(sheng)(sheng)物的(de)(de)活(huo)動(dong)造成，而(er)(er)大多(duo)數(shu)微(wei)生(sheng)(sheng)物（如(ru)霉菌(jun)和(he)(he)酵(jiao)母菌(jun)）的(de)(de)生(sheng)(sheng)存是(shi)需(xu)要(yao)氧(yang)(yang)(yang)(yang)(yang)氣(qi)(qi)的(de)(de)，而(er)(er)真(zhen)(zhen)空包(bao)裝(zhuang)就是(shi)運用這個原理(li)，把包(bao)裝(zhuang)袋內和(he)(he)食(shi)(shi)(shi)(shi)品(pin)(pin)(pin)(pin)細胞內的(de)(de)氧(yang)(yang)(yang)(yang)(yang)氣(qi)(qi)抽掉，使(shi)(shi)微(wei)物物失(shi)去“生(sheng)(sheng)存的(de)(de)環境”。實驗(yan)證明：當包(bao)裝(zhuang)袋內的(de)(de)氧(yang)(yang)(yang)(yang)(yang)氣(qi)(qi)濃度≤1%時(shi)，微(wei)生(sheng)(sheng)物的(de)(de)生(sheng)(sheng)長和(he)(he)繁(fan)殖(zhi)(zhi)(zhi)速(su)(su)度就急(ji)劇下降，氧(yang)(yang)(yang)(yang)(yang)氣(qi)(qi)濃度≤0.5%時(shi)，大多(duo)數(shu)微(wei)生(sheng)(sheng)物將受到抑制(zhi)而(er)(er)停止(zhi)繁(fan)殖(zhi)(zhi)(zhi)。（注：真(zhen)(zhen)空包(bao)裝(zhuang)不(bu)能抑制(zhi)厭氧(yang)(yang)(yang)(yang)(yang)菌(jun)的(de)(de)繁(fan)殖(zhi)(zhi)(zhi)和(he)(he)酶反(fan)應引(yin)起的(de)(de)食(shi)(shi)(shi)(shi)品(pin)(pin)(pin)(pin)變(bian)(bian)(bian)質(zhi)(zhi)和(he)(he)變(bian)(bian)(bian)色(se)，因此還(huan)(huan)需(xu)與其它輔助(zhu)方法(fa)結合(he)，如(ru)冷藏、速(su)(su)凍、脫水、高(gao)溫(wen)殺(sha)菌(jun)、輻照 滅菌(jun)、微(wei)波殺(sha)菌(jun)、鹽腌制(zhi)等。）真(zhen)(zhen)空除(chu)(chu)氧(yang)(yang)(yang)(yang)(yang)除(chu)(chu)了(le)抑制(zhi)微(wei)生(sheng)(sheng)物的(de)(de)生(sheng)(sheng)長和(he)(he)繁(fan)殖(zhi)(zhi)(zhi)外，另(ling)一個重要(yao)功能是(shi)防(fang)止(zhi)食(shi)(shi)(shi)(shi)品(pin)(pin)(pin)(pin)氧(yang)(yang)(yang)(yang)(yang)化，因油脂(zhi)類食(shi)(shi)(shi)(shi)品(pin)(pin)(pin)(pin)中(zhong)含有大量不(bu)飽和(he)(he)脂(zhi)肪酸，受氧(yang)(yang)(yang)(yang)(yang)的(de)(de)作(zuo)用而(er)(er)氧(yang)(yang)(yang)(yang)(yang)化，使(shi)(shi)食(shi)(shi)(shi)(shi)品(pin)(pin)(pin)(pin)變(bian)(bian)(bian)味、變(bian)(bian)(bian)質(zhi)(zhi)，此外，氧(yang)(yang)(yang)(yang)(yang)化還(huan)(huan)使(shi)(shi)維生(sheng)(sheng)素A和(he)(he)C損失(shi)，食(shi)(shi)(shi)(shi)品(pin)(pin)(pin)(pin)色(se)素中(zhong)的(de)(de)不(bu)穩定物質(zhi)(zhi)受氧(yang)(yang)(yang)(yang)(yang)的(de)(de)作(zuo)用，使(shi)(shi)顏色(se)變(bian)(bian)(bian)暗。所以，除(chu)(chu)氧(yang)(yang)(yang)(yang)(yang)能有效地防(fang)止(zhi)食(shi)(shi)(shi)(shi)品(pin)(pin)(pin)(pin)變(bian)(bian)(bian)質(zhi)(zhi)，保持其色(se)、香、味及營(ying)養(yang)價值。