真(zhen)空(kong)(kong)袋的主要作(zuo)用(yong)是(shi)除氧(yang)(yang)，以有利于防(fang)止食品(pin)變(bian)質(zhi)，其原(yuan)理也(ye)比較簡單，因食品(pin)霉(mei)腐變(bian)質(zhi)主要由微(wei)(wei)生(sheng)(sheng)(sheng)物(wu)(wu)(wu)的活動造成，而大(da)多數微(wei)(wei)生(sheng)(sheng)(sheng)物(wu)(wu)(wu)（如霉(mei)菌和(he)酵母菌）的生(sheng)(sheng)(sheng)存是(shi)需要氧(yang)(yang)氣(qi)(qi)的，而真(zhen)空(kong)(kong)包(bao)裝(zhuang)就是(shi)運用(yong)這個(ge)原(yuan)理，把(ba)包(bao)裝(zhuang)袋內(nei)和(he)食品(pin)細胞內(nei)的氧(yang)(yang)氣(qi)(qi)抽掉，使(shi)微(wei)(wei)物(wu)(wu)(wu)物(wu)(wu)(wu)失去“生(sheng)(sheng)(sheng)存的環境”。實驗證(zheng)明(ming)：當包(bao)裝(zhuang)袋內(nei)的氧(yang)(yang)氣(qi)(qi)濃度(du)≤1%時，微(wei)(wei)生(sheng)(sheng)(sheng)物(wu)(wu)(wu)的生(sheng)(sheng)(sheng)長和(he)繁(fan)殖(zhi)速度(du)就急劇下降，氧(yang)(yang)氣(qi)(qi)濃度(du)≤0.5%時，大(da)多數微(wei)(wei)生(sheng)(sheng)(sheng)物(wu)(wu)(wu)將受(shou)到抑制(zhi)而停止繁(fan)殖(zhi)。（注：真(zhen)空(kong)(kong)包(bao)裝(zhuang)不(bu)能(neng)抑制(zhi)厭氧(yang)(yang)菌的繁(fan)殖(zhi)和(he)酶反應引起的食品(pin)變(bian)質(zhi)和(he)變(bian)色(se)(se)，因此(ci)還需與(yu)其它輔助(zhu)方法結(jie)合(he)，如冷藏、速凍、脫水、高溫殺菌、輻照 滅菌、微(wei)(wei)波(bo)殺菌、鹽腌制(zhi)等。）真(zhen)空(kong)(kong)除氧(yang)(yang)除了(le)抑制(zhi)微(wei)(wei)生(sheng)(sheng)(sheng)物(wu)(wu)(wu)的生(sheng)(sheng)(sheng)長和(he)繁(fan)殖(zhi)外，另一個(ge)重要功能(neng)是(shi)防(fang)止食品(pin)氧(yang)(yang)化(hua)，因油脂類食品(pin)中含有大(da)量不(bu)飽(bao)和(he)脂肪酸(suan)，受(shou)氧(yang)(yang)的作(zuo)用(yong)而氧(yang)(yang)化(hua)，使(shi)食品(pin)變(bian)味、變(bian)質(zhi)，此(ci)外，氧(yang)(yang)化(hua)還使(shi)維生(sheng)(sheng)(sheng)素A和(he)C損(sun)失，食品(pin)色(se)(se)素中的不(bu)穩(wen)定物(wu)(wu)(wu)質(zhi)受(shou)氧(yang)(yang)的作(zuo)用(yong)，使(shi)顏色(se)(se)變(bian)暗。所以，除氧(yang)(yang)能(neng)有效地防(fang)止食品(pin)變(bian)質(zhi)，保持其色(se)(se)、香、味及營養價值。