真(zhen)空(kong)袋(dai)的主要作(zuo)(zuo)用(yong)是除(chu)(chu)氧(yang)(yang)(yang)(yang)(yang)，以(yi)有利(li)于(yu)防(fang)止(zhi)食(shi)品(pin)變(bian)(bian)質(zhi)(zhi)，其原理也比(bi)較(jiao)簡(jian)單(dan)，因(yin)食(shi)品(pin)霉腐變(bian)(bian)質(zhi)(zhi)主要由微(wei)(wei)生(sheng)(sheng)物的活動造成，而(er)大多(duo)數微(wei)(wei)生(sheng)(sheng)物（如霉菌(jun)和(he)(he)酵母菌(jun)）的生(sheng)(sheng)存是需要氧(yang)(yang)(yang)(yang)(yang)氣的，而(er)真(zhen)空(kong)包裝(zhuang)(zhuang)就是運(yun)用(yong)這個(ge)原理，把包裝(zhuang)(zhuang)袋(dai)內和(he)(he)食(shi)品(pin)細胞內的氧(yang)(yang)(yang)(yang)(yang)氣抽掉(diao)，使(shi)(shi)(shi)微(wei)(wei)物物失去“生(sheng)(sheng)存的環(huan)境”。實驗(yan)證明：當包裝(zhuang)(zhuang)袋(dai)內的氧(yang)(yang)(yang)(yang)(yang)氣濃(nong)度(du)≤1%時(shi)，微(wei)(wei)生(sheng)(sheng)物的生(sheng)(sheng)長和(he)(he)繁殖速度(du)就急(ji)劇下降，氧(yang)(yang)(yang)(yang)(yang)氣濃(nong)度(du)≤0.5%時(shi)，大多(duo)數微(wei)(wei)生(sheng)(sheng)物將受(shou)(shou)到(dao)抑制(zhi)而(er)停止(zhi)繁殖。（注：真(zhen)空(kong)包裝(zhuang)(zhuang)不(bu)(bu)能(neng)抑制(zhi)厭氧(yang)(yang)(yang)(yang)(yang)菌(jun)的繁殖和(he)(he)酶反應引(yin)起的食(shi)品(pin)變(bian)(bian)質(zhi)(zhi)和(he)(he)變(bian)(bian)色(se)(se)，因(yin)此還(huan)需與其它(ta)輔助方法結合，如冷藏、速凍、脫水、高溫殺菌(jun)、輻照 滅菌(jun)、微(wei)(wei)波殺菌(jun)、鹽腌制(zhi)等(deng)。）真(zhen)空(kong)除(chu)(chu)氧(yang)(yang)(yang)(yang)(yang)除(chu)(chu)了抑制(zhi)微(wei)(wei)生(sheng)(sheng)物的生(sheng)(sheng)長和(he)(he)繁殖外(wai)，另一個(ge)重要功(gong)能(neng)是防(fang)止(zhi)食(shi)品(pin)氧(yang)(yang)(yang)(yang)(yang)化，因(yin)油脂類食(shi)品(pin)中含有大量(liang)不(bu)(bu)飽和(he)(he)脂肪酸，受(shou)(shou)氧(yang)(yang)(yang)(yang)(yang)的作(zuo)(zuo)用(yong)而(er)氧(yang)(yang)(yang)(yang)(yang)化，使(shi)(shi)(shi)食(shi)品(pin)變(bian)(bian)味、變(bian)(bian)質(zhi)(zhi)，此外(wai)，氧(yang)(yang)(yang)(yang)(yang)化還(huan)使(shi)(shi)(shi)維生(sheng)(sheng)素A和(he)(he)C損(sun)失，食(shi)品(pin)色(se)(se)素中的不(bu)(bu)穩定物質(zhi)(zhi)受(shou)(shou)氧(yang)(yang)(yang)(yang)(yang)的作(zuo)(zuo)用(yong)，使(shi)(shi)(shi)顏色(se)(se)變(bian)(bian)暗。所以(yi)，除(chu)(chu)氧(yang)(yang)(yang)(yang)(yang)能(neng)有效(xiao)地防(fang)止(zhi)食(shi)品(pin)變(bian)(bian)質(zhi)(zhi)，保(bao)持其色(se)(se)、香、味及營養價(jia)值(zhi)。