根據德國冷(leng)凍產品(pin)(pin)(pin)研(yan)究所的(de)(de)統計，食品(pin)(pin)(pin)業(ye)，食品(pin)(pin)(pin)貿易業(ye)和(he)外圍餐飲市場(chang)中的(de)(de)冷(leng)凍食品(pin)(pin)(pin)（不包括冰淇淋）的(de)(de)營(ying)業(ye)額在過去的(de)(de)十年中增長了幾乎(hu)60%，在2007年達(da)到了313.6萬噸。人均消費(fei)量從26.6公斤(jin)上升到38.1公斤(jin)，超過了38公斤(jin)這一刻(ke)度(du)線(xian)。冷(leng)凍產品(pin)(pin)(pin)的(de)(de)主要優點是消費(fei)者可以將冷(leng)凍食品(pin)(pin)(pin)儲存很(hen)長時間，而食品(pin)(pin)(pin)不會發生質量的(de)(de)改變(bian)或者營(ying)養的(de)(de)喪失。更重(zhong)要的(de)(de)是，冷(leng)凍產品(pin)(pin)(pin)可以一直儲存到需要使用時候為止。

　　很多食(shi)品(pin)都(dou)可以冷凍儲(chu)存保鮮(xian)，不受季節或者時(shi)間的影響。除了多年來人們冷凍魚、蔬(shu)菜和(he)馬鈴(ling)薯外，現在的冷凍方(fang)便食(shi)品(pin)還有(you)點(dian)心、烘烤食(shi)品(pin)和(he)比薩。

　　冷(leng)(leng)凍(dong)(dong)(dong)(dong)(dong)主要(yao)是(shi)幫助保(bao)存食(shi)(shi)品(pin)(pin)。在某些情況下冷(leng)(leng)凍(dong)(dong)(dong)(dong)(dong)也是(shi)一(yi)(yi)個重(zhong)要(yao)的(de)(de)(de)加工過程，例如(ru)冷(leng)(leng)凍(dong)(dong)(dong)(dong)(dong)曬干咖啡。決定冷(leng)(leng)凍(dong)(dong)(dong)(dong)(dong)產(chan)品(pin)(pin)質量的(de)(de)(de)關(guan)鍵(jian)因(yin)素不(bu)僅(jin)涉及(ji)到(dao)原材(cai)料是(shi)否適合冷(leng)(leng)凍(dong)(dong)(dong)(dong)(dong)，選擇(ze)合適的(de)(de)(de)冷(leng)(leng)凍(dong)(dong)(dong)(dong)(dong)技術(shu)也很(hen)(hen)重(zhong)要(yao)。冷(leng)(leng)凍(dong)(dong)(dong)(dong)(dong)食(shi)(shi)品(pin)(pin)依靠的(de)(de)(de)不(bu)僅(jin)僅(jin)是(shi)合適的(de)(de)(de)溫(wen)度(du)(du)，時(shi)(shi)間(jian)安排也很(hen)(hen)重(zhong)要(yao)。目前冷(leng)(leng)凍(dong)(dong)(dong)(dong)(dong)技術(shu)的(de)(de)(de)主要(yao)區(qu)別(bie)在于熱傳導速(su)率。冷(leng)(leng)凍(dong)(dong)(dong)(dong)(dong)食(shi)(shi)品(pin)(pin)時(shi)(shi)的(de)(de)(de)重(zhong)點是(shi)將食(shi)(shi)品(pin)(pin)降(jiang)到(dao)至少零下18度(du)(du)這(zhe)一(yi)(yi)核心溫(wen)度(du)(du)的(de)(de)(de)速(su)度(du)(du)。如(ru)果冷(leng)(leng)凍(dong)(dong)(dong)(dong)(dong)過程太長，水分子(zi)形成的(de)(de)(de)大冰晶將破(po)壞(huai)細(xi)胞膜(mo)和組織，冷(leng)(leng)凍(dong)(dong)(dong)(dong)(dong)食(shi)(shi)品(pin)(pin)的(de)(de)(de)結構和形狀都將發生(sheng)改變，不(bu)僅(jin)維生(sheng)素和營養會遭到(dao)破(po)壞(huai)，食(shi)(shi)品(pin)(pin)也會失去(qu)原有的(de)(de)(de)味道。但是(shi)，如(ru)果冷(leng)(leng)凍(dong)(dong)(dong)(dong)(dong)過程特別(bie)快，水將凍(dong)(dong)(dong)(dong)(dong)結成非常小(xiao)的(de)(de)(de)晶體，這(zhe)僅(jin)僅(jin)會稍稍破(po)壞(huai)食(shi)(shi)品(pin)(pin)基(ji)質。為了做到(dao)這(zhe)一(yi)(yi)點，冷(leng)(leng)凍(dong)(dong)(dong)(dong)(dong)速(su)率，也就是(shi)冰界面在食(shi)(shi)品(pin)(pin)中的(de)(de)(de)移動速(su)度(du)(du)至少要(yao)達到(dao)每小(xiao)時(shi)(shi)一(yi)(yi)厘米。一(yi)(yi)般(ban)來(lai)說，標準的(de)(de)(de)家庭冷(leng)(leng)凍(dong)(dong)(dong)(dong)(dong)設備冷(leng)(leng)凍(dong)(dong)(dong)(dong)(dong)速(su)率平均為每小(xiao)時(shi)(shi)0.1厘米。

　　謹慎保存

　　工業(ye)上冷(leng)(leng)(leng)(leng)(leng)凍(dong)(dong)(dong)食品(pin)(pin)(pin)(pin)可以(yi)采用(yong)(yong)以(yi)下方(fang)(fang)法(fa)：氣(qi)(qi)流(liu)冷(leng)(leng)(leng)(leng)(leng)凍(dong)(dong)(dong)、接(jie)(jie)(jie)觸(chu)(chu)冷(leng)(leng)(leng)(leng)(leng)凍(dong)(dong)(dong)和低溫冷(leng)(leng)(leng)(leng)(leng)凍(dong)(dong)(dong)。氣(qi)(qi)流(liu)冷(leng)(leng)(leng)(leng)(leng)凍(dong)(dong)(dong)、接(jie)(jie)(jie)觸(chu)(chu)冷(leng)(leng)(leng)(leng)(leng)凍(dong)(dong)(dong)屬(shu)于(yu)傳(chuan)統方(fang)(fang)式，冷(leng)(leng)(leng)(leng)(leng)凍(dong)(dong)(dong)的(de)(de)低溫主要(yao)(yao)由制冷(leng)(leng)(leng)(leng)(leng)壓縮機(ji)來(lai)實現(xian)。這種方(fang)(fang)式主要(yao)(yao)使(shi)用(yong)(yong)通(tong)道式冷(leng)(leng)(leng)(leng)(leng)凍(dong)(dong)(dong)機(ji)或(huo)者流(liu)化(hua)床(chuang)通(tong)過(guo)氣(qi)(qi)流(liu)進行冷(leng)(leng)(leng)(leng)(leng)凍(dong)(dong)(dong)。將要(yao)(yao)冷(leng)(leng)(leng)(leng)(leng)凍(dong)(dong)(dong)的(de)(de)食品(pin)(pin)(pin)(pin)放在(zai)輸(shu)送(song)帶上，冷(leng)(leng)(leng)(leng)(leng)空(kong)氣(qi)(qi)從通(tong)道上傳(chuan)送(song)過(guo)來(lai)，從食品(pin)(pin)(pin)(pin)上流(liu)過(guo)。通(tong)道式氣(qi)(qi)流(liu)冷(leng)(leng)(leng)(leng)(leng)凍(dong)(dong)(dong)適用(yong)(yong)于(yu)所有包(bao)(bao)(bao)裝食品(pin)(pin)(pin)(pin)、非包(bao)(bao)(bao)裝食品(pin)(pin)(pin)(pin)、規(gui)(gui)則(ze)形狀(zhuang)食品(pin)(pin)(pin)(pin)和非規(gui)(gui)則(ze)形狀(zhuang)食品(pin)(pin)(pin)(pin)。流(liu)化(hua)床(chuang)冷(leng)(leng)(leng)(leng)(leng)凍(dong)(dong)(dong)時，底(di)部網槽(cao)將冷(leng)(leng)(leng)(leng)(leng)空(kong)氣(qi)(qi)向上推動，松(song)散、未包(bao)(bao)(bao)裝的(de)(de)食品(pin)(pin)(pin)(pin)來(lai)回移動，被(bei)冷(leng)(leng)(leng)(leng)(leng)空(kong)氣(qi)(qi)凍(dong)(dong)(dong)結。使(shi)用(yong)(yong)冷(leng)(leng)(leng)(leng)(leng)凍(dong)(dong)(dong)帶、柔(rou)性鋼帶或(huo)者旋轉氣(qi)(qi)缸(gang)是接(jie)(jie)(jie)觸(chu)(chu)冷(leng)(leng)(leng)(leng)(leng)凍(dong)(dong)(dong)中(zhong)另一種傳(chuan)統的(de)(de)冷(leng)(leng)(leng)(leng)(leng)凍(dong)(dong)(dong)方(fang)(fang)法(fa)。這種方(fang)(fang)法(fa)中(zhong)，包(bao)(bao)(bao)裝食品(pin)(pin)(pin)(pin)被(bei)放在(zai)金屬(shu)板之間(jian)，冷(leng)(leng)(leng)(leng)(leng)卻劑在(zai)金屬(shu)板之間(jian)流(liu)動，將金屬(shu)板冷(leng)(leng)(leng)(leng)(leng)卻到零下40°C左右。接(jie)(jie)(jie)觸(chu)(chu)冷(leng)(leng)(leng)(leng)(leng)凍(dong)(dong)(dong)主要(yao)(yao)用(yong)(yong)于(yu)冷(leng)(leng)(leng)(leng)(leng)凍(dong)(dong)(dong)塊狀(zhuang)食品(pin)(pin)(pin)(pin)例如魚(yu)片或(huo)者奶油(you)菠(bo)菜等。

　　低溫冷凍，潛力無(wu)窮

　　越來越多的(de)(de)(de)(de)冷凍(dong)(dong)產品(pin)被(bei)分成(cheng)小塊銷售(shou)。意大利(li)面、米飯、海鮮(xian)、蔬菜或(huo)者(zhe)這些食(shi)(shi)品(pin)的(de)(de)(de)(de)混合物采(cai)用的(de)(de)(de)(de)都是分散(san)冷凍(dong)(dong)，低溫(wen)冷凍(dong)(dong)可以實現這一點(dian)。將要冷凍(dong)(dong)的(de)(de)(de)(de)食(shi)(shi)品(pin)放在(zai)液態氮中（零下196oC）或(huo)液態二(er)氧化碳(tan)（零下78°C），將其冷凍(dong)(dong)成(cheng)高質量的(de)(de)(de)(de)單體速(su)凍(dong)(dong)食(shi)(shi)品(pin)。低溫(wen)冷凍(dong)(dong)的(de)(de)(de)(de)內在(zai)原理比較(jiao)簡單：在(zai)進入冷凍(dong)(dong)機的(de)(de)(de)(de)那(nei)一刻(ke)，液態氮沸騰，二(er)氧化碳(tan)升(sheng)華(hua)，該過程需(xu)要的(de)(de)(de)(de)能量（熱(re)量）從食(shi)(shi)品(pin)中獲取，從而(er)導致(zhi)食(shi)(shi)品(pin)被(bei)冷卻(que)并zui終凍(dong)(dong)結。

　　低(di)(di)(di)溫(wen)冷(leng)(leng)凍(dong)(dong)(dong)(dong)機(ji)不同(tong)于傳(chuan)統的(de)(de)冷(leng)(leng)凍(dong)(dong)(dong)(dong)機(ji)，因為低(di)(di)(di)溫(wen)冷(leng)(leng)凍(dong)(dong)(dong)(dong)機(ji)的(de)(de)冷(leng)(leng)凍(dong)(dong)(dong)(dong)速率(lv)*，可(ke)以(yi)達到每小時(shi)(shi)5厘米(mi)。舉(ju)例來說，制作奶酪和酸奶的(de)(de)發酵(jiao)(jiao)(jiao)劑(ji)可(ke)以(yi)迅速被(bei)冷(leng)(leng)凍(dong)(dong)(dong)(dong)成松(song)散(san)的(de)(de)粒狀物。因為溫(wen)度迅速降(jiang)低(di)(di)(di)，高達95%的(de)(de)微(wei)生(sheng)物可(ke)以(yi)存(cun)活(huo)。這(zhe)樣，冷(leng)(leng)凍(dong)(dong)(dong)(dong)的(de)(de)發酵(jiao)(jiao)(jiao)劑(ji)容易儲存(cun)，運輸并(bing)在(zai)(zai)發酵(jiao)(jiao)(jiao)過程中使用。傳(chuan)統冷(leng)(leng)凍(dong)(dong)(dong)(dong)機(ji)的(de)(de)冷(leng)(leng)凍(dong)(dong)(dong)(dong)能力(li)設(she)計的(de)(de)時(shi)(shi)候是固定的(de)(de)，低(di)(di)(di)溫(wen)冷(leng)(leng)凍(dong)(dong)(dong)(dong)機(ji)的(de)(de)冷(leng)(leng)凍(dong)(dong)(dong)(dong)范(fan)圍廣，可(ke)以(yi)冷(leng)(leng)凍(dong)(dong)(dong)(dong)很(hen)多新(xin)產品。例如可(ke)以(yi)使用液態氮冷(leng)(leng)凍(dong)(dong)(dong)(dong)制作冰(bing)(bing)(bing)淇淋(lin)(lin)的(de)(de)果膠(jiao)。首(shou)先將(jiang)冰(bing)(bing)(bing)淇淋(lin)(lin)的(de)(de)表(biao)(biao)面進行低(di)(di)(di)溫(wen)冷(leng)(leng)凍(dong)(dong)(dong)(dong)。如果這(zhe)時(shi)(shi)把冰(bing)(bing)(bing)淇淋(lin)(lin)放在(zai)(zai)果膠(jiao)中，果膠(jiao)會(hui)均勻地散(san)在(zai)(zai)冰(bing)(bing)(bing)淇淋(lin)(lin)表(biao)(biao)面上。這(zhe)種(zhong)冷(leng)(leng)凍(dong)(dong)(dong)(dong)方法可(ke)以(yi)增厚(hou)冰(bing)(bing)(bing)淇淋(lin)(lin)的(de)(de)果膠(jiao)涂(tu)層。

　　這種現(xian)代冷(leng)凍技(ji)術發展潛力無限，但是我們(men)要記住一點：溫度保證(zheng)等于(yu)*。冷(leng)凍鏈將食品生產商(shang)、零售商(shang)和消費者緊密的(de)(de)起來。我們(men)必須牢記，只有(you)通(tong)過合適的(de)(de)儲存和運輸才能保證(zheng)產品的(de)(de)質量。