李琳++韓立鵬++梁志理++陳潔++石先哲

摘要：近年來在食品中發(fā)現(xiàn)有較多的晚期糖基化末端產(chǎn)物（AGEs），尤其是脂類加工的食品中AGEs的含量較高。食源性AGEs對人體健康具有潛在危害性。為了研究脂類食品中AGEs的生成機(jī)理，選取羧甲基賴氨酸（CML）作為AGEs的代表，將CML的產(chǎn)生和食品加工過程相關(guān)聯(lián)。按照從微觀機(jī)理到宏觀表象的整體研究思路，以模擬體系作為出發(fā)點，逐步將研究體系擴(kuò)展到真實食品體系。從反應(yīng)歷程、中間產(chǎn)物、自由基和碳源四個角度深入探討了脂類食品體系中CML的生成機(jī)理，為有效控制食品加工過程中潛在化學(xué)危害物的產(chǎn)生提供理論依據(jù)。 主要研究內(nèi)容及成果如下。 （一）非脂類模擬體系中CML的化學(xué)反應(yīng)動力學(xué) CML在100℃條件下具有熱穩(wěn)定性，能夠在食品中積累。果糖基賴氨酸（FL）和乙二醛（GO）作為生成食源性CML的重要中間產(chǎn)物，在食品加工過程都存在一個極大值點。100℃條件下FL路徑生成CML占主導(dǎo)地位，貢獻(xiàn)率為84.7%，而GO路徑生成CML占次要地位，貢獻(xiàn)率為15.3%。分別建立了100℃條件下FL路徑和GO路徑生成CML的表觀動力學(xué)方程。因此，有望通過在食品加工過程中調(diào)控加工參數(shù)和添加抑制劑等方式來控制食源性CML的產(chǎn)生。 （二）脂類模擬體系中CML的生成機(jī)理 羥基自由基（OH*）對美拉德反應(yīng)體系中生成CML的三條路徑都具有促進(jìn)作用。亞油酸（Lin）、油酸（Ole）和三油酸甘油酯（Tri）能夠促使美拉德反應(yīng)體系產(chǎn)生更多的OH*；，這些OH？促進(jìn)了模擬體系中的FL和GO向CML的轉(zhuǎn)化。甘油（Gly）對OH*具有清除作用，從而降低了模擬體系中的CML含量。就引發(fā)自由基而言，對CML的促進(jìn)作用按照從大到小排列為：Ole﹥Lin﹥Tri﹥Glu﹥Gly。 就中間產(chǎn)物而言，對CML的貢獻(xiàn)按照從大到小排列為：FL路徑（針對Glu）﹥Gly氧化產(chǎn)生GO路徑﹥GO路徑（針對葡萄糖（Glu））﹥Lin氧化產(chǎn)生GO路徑﹥Ole氧化產(chǎn)生GO路徑﹥Tri氧化產(chǎn)生GO路徑。因此，脂類對CML生成的促進(jìn)作用來源于兩個方面：（1）促使美拉德反應(yīng)模擬體系產(chǎn)生更多OH？，促進(jìn)CML的產(chǎn)生；（2）不飽和脂肪酸和Gly氧化產(chǎn)生GO，成為生成CML的碳源。 （三）植物油模擬體系中CML的生成規(guī)律 油脂對模擬體系中CML的促進(jìn)作用和油脂中不飽和脂肪酸含量存在正相關(guān)性，即含有較多不飽和脂肪酸的油脂能夠在美拉德反應(yīng)模擬體系中引發(fā)較多的OH*從而促進(jìn)GO和FL向CML轉(zhuǎn)化。因此，在食品加工過程中，含有較多不飽和脂肪酸的油脂更容易促進(jìn)CML的產(chǎn)生。 （四）真實食品體系中CML的生成規(guī)律 食品儲藏過程中，食源性CML會隨著儲藏時間的延長而逐漸積累。在食品加工過程中，脂類食品體系中CML的含量隨著油脂含量的增加而逐漸增加。

關(guān)鍵詞：晚期糖基化末端產(chǎn)物；羧甲基賴氨酸；食品；油脂；自由基；

Mechanism of carboxymethyllysine formation in lipids food system

Abstract：Food-derived glycation end products （AGEs） were potentially hazardous to human health， Nε-carboxymethyllysine （CML） was chose as a representative of AGEs. CML formation mechanism was investigated as follow to offer theory for controlling potential hazardous materials in food production process. （1） Chemical reaction kinetics of CML in non-lipid model system. CML content could accumulate in food for its thermal stability. There were both fructoselysine （FL） and glyoxal （GO） contents maximum points in their formation process. CML derived from FL played a major role with contribution rate of 84.7% for CML formation， while CML derived from GO played a minor role with contribution rate of 15.3% for CML formation. CML apparent kinetics equations through FL pathway and GO pathway were obtained respectively. Therefore， it is possible to control food-derived CML through adjusting processing variables and adding inhibitors. （2） Formation mechanism of CML in lipid model system. Hydroxyl radical （OH*） induced by Fenton reagent could promote three pathways for CML formation in Maillard reaction. linoleic acid （Lin）， oleic acid （Ole） and triglyceride （Tri） could induce more OH； in Maillard reaction model system which promoted FL and GO conversion to CML. However， glycerol （Gly） could reduce CML content in model system for its scavenging OH*； ability. The promoting CML formation abilities of lipids on modeling system were in the order of Ole﹥Lin﹥Tri﹥Glu﹥Gly. The contribution rate of Gly to CML increased with time. The promoting effect of Lin， Ole， Tri and Gly on CML formation through oxidation to GO were in the order of FL pathway﹥Gly﹥GO pathway﹥Lin﹥Ole﹥Tri. Therefore， the promoting effect of lipid on CML formation derived from two aspects： Inducing more OH* to promote CML formation； Offering carbon source for CML formation through oxidation to GO. （3） CML formation in vegetable oils model system. The promotion effect of five oils on CML formation was in the order of Soybean﹥Corn﹥Olive﹥Palm﹥Rape. Fatty acid analysis for five oils showed that the more unsaturated fatty acid the oils had， the more OH* they induced in model system. Therefore， oils with more unsaturated fatty acid in food production process were easier to increase CML formation. （4） CML formation in real food system. CML could accumulate in food storage process and CML content in lipid system increased with oil content increasing in food production process.

Keywords：advanced glycation end products； carboxymethyllysine； food； oil； free radical

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