真(zhen)空袋的(de)(de)(de)主(zhu)要作(zuo)(zuo)用(yong)是(shi)(shi)除(chu)氧(yang)(yang)，以有(you)(you)利(li)于防止(zhi)食(shi)(shi)品(pin)(pin)(pin)(pin)變(bian)質(zhi)，其原理也(ye)比較簡(jian)單，因(yin)食(shi)(shi)品(pin)(pin)(pin)(pin)霉腐(fu)變(bian)質(zhi)主(zhu)要由微(wei)(wei)生(sheng)(sheng)(sheng)(sheng)物(wu)(wu)(wu)(wu)(wu)的(de)(de)(de)活動造成，而(er)大(da)(da)(da)多(duo)數(shu)微(wei)(wei)生(sheng)(sheng)(sheng)(sheng)物(wu)(wu)(wu)(wu)(wu)（如霉菌(jun)和(he)(he)酵(jiao)母菌(jun)）的(de)(de)(de)生(sheng)(sheng)(sheng)(sheng)存是(shi)(shi)需要氧(yang)(yang)氣的(de)(de)(de)，而(er)真(zhen)空包裝就是(shi)(shi)運用(yong)這個原理，把包裝袋內和(he)(he)食(shi)(shi)品(pin)(pin)(pin)(pin)細胞內的(de)(de)(de)氧(yang)(yang)氣抽掉，使微(wei)(wei)物(wu)(wu)(wu)(wu)(wu)物(wu)(wu)(wu)(wu)(wu)失去“生(sheng)(sheng)(sheng)(sheng)存的(de)(de)(de)環境”。實驗證明：當包裝袋內的(de)(de)(de)氧(yang)(yang)氣濃度≤1%時(shi)，微(wei)(wei)生(sheng)(sheng)(sheng)(sheng)物(wu)(wu)(wu)(wu)(wu)的(de)(de)(de)生(sheng)(sheng)(sheng)(sheng)長和(he)(he)繁(fan)殖速度就急劇下(xia)降，氧(yang)(yang)氣濃度≤0.5%時(shi)，大(da)(da)(da)多(duo)數(shu)微(wei)(wei)生(sheng)(sheng)(sheng)(sheng)物(wu)(wu)(wu)(wu)(wu)將受到抑制(zhi)(zhi)而(er)停止(zhi)繁(fan)殖。（注：真(zhen)空包裝不(bu)能抑制(zhi)(zhi)厭氧(yang)(yang)菌(jun)的(de)(de)(de)繁(fan)殖和(he)(he)酶反應引起(qi)的(de)(de)(de)食(shi)(shi)品(pin)(pin)(pin)(pin)變(bian)質(zhi)和(he)(he)變(bian)色，因(yin)此還(huan)需與其它輔助方法結合，如冷(leng)藏、速凍、脫水、高(gao)溫殺(sha)(sha)菌(jun)、輻照 滅菌(jun)、微(wei)(wei)波殺(sha)(sha)菌(jun)、鹽腌制(zhi)(zhi)等。）真(zhen)空除(chu)氧(yang)(yang)除(chu)了抑制(zhi)(zhi)微(wei)(wei)生(sheng)(sheng)(sheng)(sheng)物(wu)(wu)(wu)(wu)(wu)的(de)(de)(de)生(sheng)(sheng)(sheng)(sheng)長和(he)(he)繁(fan)殖外，另一(yi)個重要功(gong)能是(shi)(shi)防止(zhi)食(shi)(shi)品(pin)(pin)(pin)(pin)氧(yang)(yang)化(hua)(hua)，因(yin)油脂(zhi)類食(shi)(shi)品(pin)(pin)(pin)(pin)中(zhong)含有(you)(you)大(da)(da)(da)量(liang)不(bu)飽和(he)(he)脂(zhi)肪酸，受氧(yang)(yang)的(de)(de)(de)作(zuo)(zuo)用(yong)而(er)氧(yang)(yang)化(hua)(hua)，使食(shi)(shi)品(pin)(pin)(pin)(pin)變(bian)味(wei)、變(bian)質(zhi)，此外，氧(yang)(yang)化(hua)(hua)還(huan)使維生(sheng)(sheng)(sheng)(sheng)素A和(he)(he)C損失，食(shi)(shi)品(pin)(pin)(pin)(pin)色素中(zhong)的(de)(de)(de)不(bu)穩定物(wu)(wu)(wu)(wu)(wu)質(zhi)受氧(yang)(yang)的(de)(de)(de)作(zuo)(zuo)用(yong)，使顏色變(bian)暗。所以，除(chu)氧(yang)(yang)能有(you)(you)效地防止(zhi)食(shi)(shi)品(pin)(pin)(pin)(pin)變(bian)質(zhi)，保持其色、香、味(wei)及營(ying)養(yang)價值。