真空(kong)袋主(zhu)(zhu)要作用是(shi)除氧(yang)(yang)(yang)，以有(you)利于防止(zhi)食品變質，其(qi)原理也比(bi)較簡(jian)單，因食品霉(mei)(mei)腐變質主(zhu)(zhu)要由微(wei)(wei)生(sheng)物(wu)(wu)的活(huo)動造成，而大(da)多數微(wei)(wei)生(sheng)物(wu)(wu)（如霉(mei)(mei)菌(jun)和酵母菌(jun)）的生(sheng)存是(shi)需要氧(yang)(yang)(yang)氣(qi)(qi)的，而真空(kong)包裝(zhuang)就(jiu)是(shi)運用這個原理，把(ba)包裝(zhuang)袋內(nei)(nei)和食品細胞(bao)內(nei)(nei)的氧(yang)(yang)(yang)氣(qi)(qi)抽掉，使微(wei)(wei)物(wu)(wu)物(wu)(wu)失去“生(sheng)存的環境”。實驗證明(ming)：當包裝(zhuang)袋內(nei)(nei)的氧(yang)(yang)(yang)氣(qi)(qi)濃(nong)(nong)度≤1%時(shi)，微(wei)(wei)生(sheng)物(wu)(wu)的生(sheng)長和繁殖速度就(jiu)急劇下降，氧(yang)(yang)(yang)氣(qi)(qi)濃(nong)(nong)度≤0.5%時(shi)，大(da)多數微(wei)(wei)生(sheng)物(wu)(wu)將受到抑制而停止(zhi)繁殖。