真(zhen)空(kong)袋(dai)(dai)的(de)(de)主(zhu)要作(zuo)用(yong)是(shi)除氧(yang)(yang)(yang)，以有利于(yu)防(fang)止食(shi)品(pin)(pin)(pin)變(bian)(bian)(bian)質(zhi)(zhi)，其原理也比較簡單，因食(shi)品(pin)(pin)(pin)霉(mei)腐變(bian)(bian)(bian)質(zhi)(zhi)主(zhu)要由微生(sheng)(sheng)(sheng)(sheng)物(wu)(wu)的(de)(de)活動造成，而(er)(er)大(da)(da)多數(shu)(shu)微生(sheng)(sheng)(sheng)(sheng)物(wu)(wu)（如(ru)霉(mei)菌(jun)和(he)(he)(he)酵母(mu)菌(jun)）的(de)(de)生(sheng)(sheng)(sheng)(sheng)存是(shi)需要氧(yang)(yang)(yang)氣的(de)(de)，而(er)(er)真(zhen)空(kong)包(bao)裝就是(shi)運(yun)用(yong)這(zhe)個原理，把包(bao)裝袋(dai)(dai)內(nei)和(he)(he)(he)食(shi)品(pin)(pin)(pin)細胞內(nei)的(de)(de)氧(yang)(yang)(yang)氣抽掉，使微物(wu)(wu)物(wu)(wu)失(shi)去“生(sheng)(sheng)(sheng)(sheng)存的(de)(de)環境”。實驗證明(ming)：當包(bao)裝袋(dai)(dai)內(nei)的(de)(de)氧(yang)(yang)(yang)氣濃度(du)(du)≤1%時，微生(sheng)(sheng)(sheng)(sheng)物(wu)(wu)的(de)(de)生(sheng)(sheng)(sheng)(sheng)長和(he)(he)(he)繁(fan)殖(zhi)速度(du)(du)就急劇(ju)下降(jiang)，氧(yang)(yang)(yang)氣濃度(du)(du)≤0.5%時，大(da)(da)多數(shu)(shu)微生(sheng)(sheng)(sheng)(sheng)物(wu)(wu)將受(shou)(shou)到抑制(zhi)(zhi)而(er)(er)停止繁(fan)殖(zhi)。（注：真(zhen)空(kong)包(bao)裝不(bu)(bu)能(neng)抑制(zhi)(zhi)厭氧(yang)(yang)(yang)菌(jun)的(de)(de)繁(fan)殖(zhi)和(he)(he)(he)酶反應引起(qi)的(de)(de)食(shi)品(pin)(pin)(pin)變(bian)(bian)(bian)質(zhi)(zhi)和(he)(he)(he)變(bian)(bian)(bian)色(se)，因此還需與(yu)其它輔助(zhu)方法結(jie)合，如(ru)冷藏(zang)、速凍(dong)、脫水、高溫殺菌(jun)、輻照 滅(mie)菌(jun)、微波殺菌(jun)、鹽腌制(zhi)(zhi)等。）真(zhen)空(kong)除氧(yang)(yang)(yang)除了抑制(zhi)(zhi)微生(sheng)(sheng)(sheng)(sheng)物(wu)(wu)的(de)(de)生(sheng)(sheng)(sheng)(sheng)長和(he)(he)(he)繁(fan)殖(zhi)外，另一(yi)個重要功能(neng)是(shi)防(fang)止食(shi)品(pin)(pin)(pin)氧(yang)(yang)(yang)化，因油(you)脂類食(shi)品(pin)(pin)(pin)中含有大(da)(da)量不(bu)(bu)飽(bao)和(he)(he)(he)脂肪酸，受(shou)(shou)氧(yang)(yang)(yang)的(de)(de)作(zuo)用(yong)而(er)(er)氧(yang)(yang)(yang)化，使食(shi)品(pin)(pin)(pin)變(bian)(bian)(bian)味(wei)(wei)、變(bian)(bian)(bian)質(zhi)(zhi)，此外，氧(yang)(yang)(yang)化還使維生(sheng)(sheng)(sheng)(sheng)素A和(he)(he)(he)C損失(shi)，食(shi)品(pin)(pin)(pin)色(se)素中的(de)(de)不(bu)(bu)穩定物(wu)(wu)質(zhi)(zhi)受(shou)(shou)氧(yang)(yang)(yang)的(de)(de)作(zuo)用(yong)，使顏色(se)變(bian)(bian)(bian)暗。所以，除氧(yang)(yang)(yang)能(neng)有效地防(fang)止食(shi)品(pin)(pin)(pin)變(bian)(bian)(bian)質(zhi)(zhi)，保持其色(se)、香、味(wei)(wei)及營(ying)養價值。