真(zhen)(zhen)空(kong)(kong)袋的(de)(de)(de)主(zhu)要作(zuo)用(yong)是(shi)(shi)除(chu)(chu)(chu)氧(yang)(yang)(yang)(yang)(yang)(yang)，以有利于防止(zhi)食(shi)(shi)品(pin)(pin)(pin)變(bian)(bian)(bian)質(zhi)(zhi)，其原(yuan)理也比較簡單，因食(shi)(shi)品(pin)(pin)(pin)霉(mei)(mei)腐變(bian)(bian)(bian)質(zhi)(zhi)主(zhu)要由微(wei)生(sheng)(sheng)(sheng)(sheng)物(wu)(wu)的(de)(de)(de)活動造成(cheng)，而(er)大(da)(da)多(duo)數微(wei)生(sheng)(sheng)(sheng)(sheng)物(wu)(wu)（如(ru)霉(mei)(mei)菌(jun)(jun)(jun)和酵(jiao)母菌(jun)(jun)(jun)）的(de)(de)(de)生(sheng)(sheng)(sheng)(sheng)存是(shi)(shi)需(xu)要氧(yang)(yang)(yang)(yang)(yang)(yang)氣(qi)(qi)的(de)(de)(de)，而(er)真(zhen)(zhen)空(kong)(kong)包裝就(jiu)是(shi)(shi)運用(yong)這個(ge)(ge)原(yuan)理，把(ba)包裝袋內和食(shi)(shi)品(pin)(pin)(pin)細胞內的(de)(de)(de)氧(yang)(yang)(yang)(yang)(yang)(yang)氣(qi)(qi)抽掉，使(shi)(shi)微(wei)物(wu)(wu)物(wu)(wu)失去(qu)“生(sheng)(sheng)(sheng)(sheng)存的(de)(de)(de)環境”。實驗(yan)證明：當(dang)包裝袋內的(de)(de)(de)氧(yang)(yang)(yang)(yang)(yang)(yang)氣(qi)(qi)濃度(du)(du)≤1%時，微(wei)生(sheng)(sheng)(sheng)(sheng)物(wu)(wu)的(de)(de)(de)生(sheng)(sheng)(sheng)(sheng)長(chang)和繁(fan)殖(zhi)速度(du)(du)就(jiu)急劇下降，氧(yang)(yang)(yang)(yang)(yang)(yang)氣(qi)(qi)濃度(du)(du)≤0.5%時，大(da)(da)多(duo)數微(wei)生(sheng)(sheng)(sheng)(sheng)物(wu)(wu)將受到抑(yi)制(zhi)而(er)停止(zhi)繁(fan)殖(zhi)。（注：真(zhen)(zhen)空(kong)(kong)包裝不(bu)(bu)能(neng)抑(yi)制(zhi)厭氧(yang)(yang)(yang)(yang)(yang)(yang)菌(jun)(jun)(jun)的(de)(de)(de)繁(fan)殖(zhi)和酶反應引起的(de)(de)(de)食(shi)(shi)品(pin)(pin)(pin)變(bian)(bian)(bian)質(zhi)(zhi)和變(bian)(bian)(bian)色(se)，因此(ci)還(huan)需(xu)與(yu)其它輔助方法結合，如(ru)冷藏、速凍、脫(tuo)水(shui)、高溫殺(sha)(sha)菌(jun)(jun)(jun)、輻照 滅菌(jun)(jun)(jun)、微(wei)波殺(sha)(sha)菌(jun)(jun)(jun)、鹽(yan)腌制(zhi)等。）真(zhen)(zhen)空(kong)(kong)除(chu)(chu)(chu)氧(yang)(yang)(yang)(yang)(yang)(yang)除(chu)(chu)(chu)了抑(yi)制(zhi)微(wei)生(sheng)(sheng)(sheng)(sheng)物(wu)(wu)的(de)(de)(de)生(sheng)(sheng)(sheng)(sheng)長(chang)和繁(fan)殖(zhi)外(wai)，另一個(ge)(ge)重(zhong)要功(gong)能(neng)是(shi)(shi)防止(zhi)食(shi)(shi)品(pin)(pin)(pin)氧(yang)(yang)(yang)(yang)(yang)(yang)化(hua)，因油脂(zhi)類食(shi)(shi)品(pin)(pin)(pin)中含(han)有大(da)(da)量不(bu)(bu)飽和脂(zhi)肪酸，受氧(yang)(yang)(yang)(yang)(yang)(yang)的(de)(de)(de)作(zuo)用(yong)而(er)氧(yang)(yang)(yang)(yang)(yang)(yang)化(hua)，使(shi)(shi)食(shi)(shi)品(pin)(pin)(pin)變(bian)(bian)(bian)味、變(bian)(bian)(bian)質(zhi)(zhi)，此(ci)外(wai)，氧(yang)(yang)(yang)(yang)(yang)(yang)化(hua)還(huan)使(shi)(shi)維生(sheng)(sheng)(sheng)(sheng)素A和C損失，食(shi)(shi)品(pin)(pin)(pin)色(se)素中的(de)(de)(de)不(bu)(bu)穩(wen)定物(wu)(wu)質(zhi)(zhi)受氧(yang)(yang)(yang)(yang)(yang)(yang)的(de)(de)(de)作(zuo)用(yong)，使(shi)(shi)顏色(se)變(bian)(bian)(bian)暗。所以，除(chu)(chu)(chu)氧(yang)(yang)(yang)(yang)(yang)(yang)能(neng)有效地防止(zhi)食(shi)(shi)品(pin)(pin)(pin)變(bian)(bian)(bian)質(zhi)(zhi)，保持其色(se)、香(xiang)、味及營養價(jia)值。