真(zhen)空(kong)(kong)袋(dai)(dai)(dai)的(de)(de)(de)(de)(de)主(zhu)要作用(yong)(yong)是(shi)(shi)(shi)除(chu)氧(yang)(yang)，以有(you)利于防(fang)止(zhi)食(shi)(shi)(shi)品(pin)變(bian)(bian)(bian)(bian)質，其(qi)原理也比(bi)較(jiao)簡(jian)單(dan)，因(yin)食(shi)(shi)(shi)品(pin)霉腐變(bian)(bian)(bian)(bian)質主(zhu)要由微(wei)生(sheng)物的(de)(de)(de)(de)(de)活動造(zao)成(cheng)，而(er)大(da)多數微(wei)生(sheng)物（如霉菌(jun)和(he)(he)酵母菌(jun)）的(de)(de)(de)(de)(de)生(sheng)存(cun)是(shi)(shi)(shi)需要氧(yang)(yang)氣(qi)的(de)(de)(de)(de)(de)，而(er)真(zhen)空(kong)(kong)包裝就是(shi)(shi)(shi)運用(yong)(yong)這(zhe)個原理，把包裝袋(dai)(dai)(dai)內(nei)和(he)(he)食(shi)(shi)(shi)品(pin)細胞內(nei)的(de)(de)(de)(de)(de)氧(yang)(yang)氣(qi)抽掉，使(shi)(shi)微(wei)物物失去(qu)“生(sheng)存(cun)的(de)(de)(de)(de)(de)環(huan)境”。實(shi)驗證明(ming)：當包裝袋(dai)(dai)(dai)內(nei)的(de)(de)(de)(de)(de)氧(yang)(yang)氣(qi)濃度≤1%時(shi)，微(wei)生(sheng)物的(de)(de)(de)(de)(de)生(sheng)長和(he)(he)繁(fan)殖(zhi)速(su)度就急劇下降，氧(yang)(yang)氣(qi)濃度≤0.5%時(shi)，大(da)多數微(wei)生(sheng)物將受(shou)到抑(yi)制而(er)停止(zhi)繁(fan)殖(zhi)。（注：真(zhen)空(kong)(kong)包裝不能抑(yi)制厭(yan)氧(yang)(yang)菌(jun)的(de)(de)(de)(de)(de)繁(fan)殖(zhi)和(he)(he)酶反應引起的(de)(de)(de)(de)(de)食(shi)(shi)(shi)品(pin)變(bian)(bian)(bian)(bian)質和(he)(he)變(bian)(bian)(bian)(bian)色，因(yin)此還(huan)需與其(qi)它(ta)輔助方法結合，如冷藏、速(su)凍(dong)、脫水、高溫殺菌(jun)、輻(fu)照 滅菌(jun)、微(wei)波(bo)殺菌(jun)、鹽腌制等。）真(zhen)空(kong)(kong)除(chu)氧(yang)(yang)除(chu)了抑(yi)制微(wei)生(sheng)物的(de)(de)(de)(de)(de)生(sheng)長和(he)(he)繁(fan)殖(zhi)外，另一個重要功能是(shi)(shi)(shi)防(fang)止(zhi)食(shi)(shi)(shi)品(pin)氧(yang)(yang)化，因(yin)油脂(zhi)類食(shi)(shi)(shi)品(pin)中含有(you)大(da)量不飽和(he)(he)脂(zhi)肪酸(suan)，受(shou)氧(yang)(yang)的(de)(de)(de)(de)(de)作用(yong)(yong)而(er)氧(yang)(yang)化，使(shi)(shi)食(shi)(shi)(shi)品(pin)變(bian)(bian)(bian)(bian)味、變(bian)(bian)(bian)(bian)質，此外，氧(yang)(yang)化還(huan)使(shi)(shi)維生(sheng)素(su)A和(he)(he)C損失，食(shi)(shi)(shi)品(pin)色素(su)中的(de)(de)(de)(de)(de)不穩定物質受(shou)氧(yang)(yang)的(de)(de)(de)(de)(de)作用(yong)(yong)，使(shi)(shi)顏色變(bian)(bian)(bian)(bian)暗(an)。所以，除(chu)氧(yang)(yang)能有(you)效地防(fang)止(zhi)食(shi)(shi)(shi)品(pin)變(bian)(bian)(bian)(bian)質，保持其(qi)色、香、味及(ji)營養(yang)價(jia)值。