真空(kong)袋的(de)主要(yao)作(zuo)用(yong)是(shi)除氧(yang)(yang)(yang)(yang)(yang)(yang)，以(yi)有(you)利于防止(zhi)食(shi)(shi)品(pin)(pin)變(bian)(bian)(bian)質(zhi)，其原(yuan)理(li)也(ye)比較簡單(dan)，因(yin)食(shi)(shi)品(pin)(pin)霉腐變(bian)(bian)(bian)質(zhi)主要(yao)由微(wei)生物(wu)(wu)(wu)的(de)活動(dong)造成，而大(da)多數微(wei)生物(wu)(wu)(wu)（如霉菌(jun)和酵母(mu)菌(jun)）的(de)生存(cun)是(shi)需要(yao)氧(yang)(yang)(yang)(yang)(yang)(yang)氣(qi)(qi)的(de)，而真空(kong)包裝就(jiu)是(shi)運用(yong)這個原(yuan)理(li)，把包裝袋內和食(shi)(shi)品(pin)(pin)細胞內的(de)氧(yang)(yang)(yang)(yang)(yang)(yang)氣(qi)(qi)抽掉，使微(wei)物(wu)(wu)(wu)物(wu)(wu)(wu)失(shi)去“生存(cun)的(de)環境”。實驗證(zheng)明：當包裝袋內的(de)氧(yang)(yang)(yang)(yang)(yang)(yang)氣(qi)(qi)濃度≤1%時(shi)，微(wei)生物(wu)(wu)(wu)的(de)生長和繁(fan)(fan)殖(zhi)速度就(jiu)急劇下降，氧(yang)(yang)(yang)(yang)(yang)(yang)氣(qi)(qi)濃度≤0.5%時(shi)，大(da)多數微(wei)生物(wu)(wu)(wu)將受(shou)到抑制而停(ting)止(zhi)繁(fan)(fan)殖(zhi)。（注：真空(kong)包裝不(bu)能(neng)抑制厭氧(yang)(yang)(yang)(yang)(yang)(yang)菌(jun)的(de)繁(fan)(fan)殖(zhi)和酶反(fan)應引起的(de)食(shi)(shi)品(pin)(pin)變(bian)(bian)(bian)質(zhi)和變(bian)(bian)(bian)色(se)(se)，因(yin)此還(huan)(huan)需與其它(ta)輔助(zhu)方法結合，如冷(leng)藏、速凍、脫水、高溫殺(sha)菌(jun)、輻照 滅菌(jun)、微(wei)波(bo)殺(sha)菌(jun)、鹽腌制等。）真空(kong)除氧(yang)(yang)(yang)(yang)(yang)(yang)除了抑制微(wei)生物(wu)(wu)(wu)的(de)生長和繁(fan)(fan)殖(zhi)外(wai)，另一個重要(yao)功能(neng)是(shi)防止(zhi)食(shi)(shi)品(pin)(pin)氧(yang)(yang)(yang)(yang)(yang)(yang)化，因(yin)油脂(zhi)類食(shi)(shi)品(pin)(pin)中(zhong)(zhong)含有(you)大(da)量不(bu)飽和脂(zhi)肪酸，受(shou)氧(yang)(yang)(yang)(yang)(yang)(yang)的(de)作(zuo)用(yong)而氧(yang)(yang)(yang)(yang)(yang)(yang)化，使食(shi)(shi)品(pin)(pin)變(bian)(bian)(bian)味、變(bian)(bian)(bian)質(zhi)，此外(wai)，氧(yang)(yang)(yang)(yang)(yang)(yang)化還(huan)(huan)使維生素(su)A和C損失(shi)，食(shi)(shi)品(pin)(pin)色(se)(se)素(su)中(zhong)(zhong)的(de)不(bu)穩定物(wu)(wu)(wu)質(zhi)受(shou)氧(yang)(yang)(yang)(yang)(yang)(yang)的(de)作(zuo)用(yong)，使顏色(se)(se)變(bian)(bian)(bian)暗。所以(yi)，除氧(yang)(yang)(yang)(yang)(yang)(yang)能(neng)有(you)效地防止(zhi)食(shi)(shi)品(pin)(pin)變(bian)(bian)(bian)質(zhi)，保持其色(se)(se)、香、味及營養(yang)價值。