赖氨酸在Maillard 反应中形成有害产物AGEs的研究

模拟食品加工条件,构建赖氨酸—还原糖和精氨酸—赖氨酸—还原糖体系,分析各影响因素在体系发生Maillard反应中产生有害AGEs(晚期糖基化终末产物)的作用,比较两个体系添加和不添加黄酮条件下对AGEs形成量的影响。用荧光光谱法(λex/λem=370/440nm)测定AGEs的含量,考察不同因素如还原糖种类、浓度、金属离子、温度、pH和染料木素对有害AGEs形成的影响,以及赖氨酸/精氨酸并存对AGEs形成量的影响。结果表明:在赖氨酸发生Maillard反应过程中,温度越高、还原糖中核糖,糖浓度越大、pH 9.2,形成的AGEs越多;不同的金属离子对AGEs的作用各异,Mg~(2+)和Fe~(2+)能促进AGEs的形成,Ca~(2+)抑制AGEs的形成;抑制剂染料木素浓度越大(9mmol/L),AGEs抑制效果越好;赖氨酸/精氨酸混合体系中AGEs形成量主要由赖氨酸来决定。各影响因素对赖氨酸Maillard反应过程中产生AGEs均有一定作用,时间是最主要因素,其次是pH和温度;而赖氨酸/精氨酸混合体系中AGEs的形成量取决于赖氨酸的含量。     

美拉德反应产物的褐变、荧光吸收及抗氧化性的研究

采用以还原糖-氨基酸(木糖/葡萄糖分别与甘氨酸、赖氨酸、谷氨酰胺、半胱氨酸)模式美拉德反应(Maillard Reaction,MR)制备得到美拉德反应产物(MRPs),研究反应条件对MRPs的褐变程度、荧光吸收强度以及其抗氧化活性的影响,并分析MRPs的光学特征与抗氧化活性之间的联系。结果表明,还原糖和氨基酸的种类对MR的褐变强度有很大影响,其影响程度由强到弱分别为:Xly>Glc,Lys>Gly>Glu>Cys。随着反应时间的延长,各体系MRPs的褐变程度逐渐变强;而荧光吸收强度随着加热时间的延长而增强,然后在出现最大值后趋于平缓或者表现出下降的趋势。MRPs的抗氧化能力也随反应时间的延长而增强,抗氧化活性与褐变强度呈正相关,与荧光吸收特性没有表现出明显的关联。     

果糖与氨基酸美拉德反应产物的抗氧化性研究

为分析果糖参与的美拉德反应对氨基酸、多肽与蛋白质理化性质及抗氧化性的影响,利用果糖与四种代表性氨基酸(赖氨酸、甘氨酸、组氨酸、半胱氨酸)进行模式美拉德反应;考察了反应过程中体系的褐变与pH变化,并测试了体系的ABTS、DPPH自由基清除能力,铁氰化钾还原能力以及铁铜离子螯合能力在美拉德反应前后的变化。结果表明,反应体系的酸度以及褐变程度均随美拉德反应的进行逐渐增加,体系清除自由基能力与还原能力也大幅度提高。此外,氨基酸的结构与种类对美拉德反应的进行以及相应产物的性能都会产生较大影响。     

Inhibition of enzymatic browning in actual food systems by the Maillard reaction products

BACKGROUND: The Maillard reaction occurring between amino acids and sugars produces neo‐formed compounds having certain levels of antioxidant activity depending on the reaction conditions and the type of reactants. The objective of this study was to investigate enzymatic browning inhibition capacity of Maillard reaction products (MRPs) formed from different amino acids including arginine (Arg), histidine (His), lysine (Lys) and proline (Pro). RESULTS: The inhibitory effects of the MRPs on polyphenol oxidase (PPO) were determined. The total antioxidant capacity (TAC) of MRPs derived from different amino acids were in the order Arg > His > Lys > Pro. The TAC and PPO inhibition of MRPs were evaluated as a function of temperature (80–120 °C), time (1–6 h) and pH (2–12). Arg‐Glc and His‐Glc MRPs exhibited strong TAC and PPO inhibition. Increasing temperature (up to 100 °C) and time also increased TAC and PPO inhibition. Kinetics analysis indicated a mixed type inhibition of PPO by MRPs. CONCLUSION: The results indicate that the MRPs derived from Arg and His under certain reaction conditions significantly prevent enzymatic browning in actual food systems. The intermediate compounds capable of preventing enzymatic browning are reductones and dehydroreductones, as confirmed by liquid chromatographic–mass spectrometric analyses. Copyright © 2010 Society of Chemical Industry     

模式美拉德反应产物的抗氧化性与反应进程的关系研究

采用还原糖(木糖和葡萄糖)和氨基酸(甘氨酸和丙氨酸)进行模式美拉德反应,测定了反应进程中pH值、荧光物质(激发波长360nm,发射波长420nm)、中间产物(294nm吸光值)、褐变程度(420nm吸光值)和颜色参数的变化。以DPPH·自由基清除能力和还原力为指标,研究了美拉德反应产物的抗氧化性与反应进程的关系。结果表明:美拉德反应产物清除DPPH·的能力与中间产物(294nm)有很好的线性关系,而美拉德反应产物的还原力与反应体系的褐变程度和亮度(L*值)有较好的线性关系。     

基于蛋白结构修饰的热加工食品伴生危害物形成及抑制研究进展

蛋白食品热加工过程中会因美拉德反应、氨基酸热解等同时产生多种危害物,包括但不仅限于晚期糖基化终末产物、杂环胺和丙烯酰胺。目前已有较多针对某一种危害物生成及抑制机制的研究,但因上述危害物具有相同的氨基酸等反应前体、甲基乙二醛等中间产物以及相似的反应路径,有必要对现有文献进行综合,为后续多种危害物的同步生成及抑制研究寻找新的出发点和突破口。本文系统介绍了蛋白食品热加工过程中氨基酸的变化和羰基化等蛋白结构的修饰,并讨论了这些变化与蛋白食品热加工过程伴生危害物的关系,以期从蛋白结构的改变理解热加工蛋白食品中多种危害物的生成及控制。结果表明,多响应动力学研究多种危害物的生成及抑制,以及高分辨率质谱研究蛋白在热加工过程中的结构修饰将是研究蛋白食品热加工伴生危害物的有效手段。     

Maillard反应合成蛋白质-多糖复合物及其应用

综述了利用美拉德反应制得的蛋白-多糖复合物的性能,这种复合物主要是在干燥状态下利用自发进行的美拉德反应制得的。同传统商业上使用的乳化剂相比,该复合物具有优良的乳化性能,热稳定性和抑菌性。因此,该复合物在工业上可以用作天然乳化剂,无毒抑菌剂。同时如果多糖与过敏原蛋白复合还具有减轻蛋白的致敏性的效果。     

食品中晚期糖基化末端产物的研究进展

晚期糖基化末端产物(advanced glycation end products, AGEs)是还原糖与氨基酸发生非酶褐变反应的产物之一。医学研究结果表明,AGEs与人类诸多疾病的发生有密切关系,而膳食摄入是体内AGEs的重要来源。但是由于AGEs种类较多,对于食品中的AGEs含量的检测尚缺乏标准的方法,食品加工工艺对食品中AGEs形成的影响报道较少。因此,本文从食品中AGEs形成、结构、检测方法及AGEs在体内代谢、对人体健康影响和预防措施等方面对AGEs进行了较系统的阐述,为进一步研究AGEs奠定基础。     

加工条件对BSA-Glucose模拟体系中晚期糖基化末端产物形成的影响

建立牛血清白蛋白-葡萄糖(BSA-Glucose)热加工模拟体系,用荧光光谱法测定激发光谱/发射光谱(λex/λem)=370nm/440nm荧光值,研究加热温度、加热时间、初始pH值、蛋白质浓度、抗氧化剂对晚期糖基化末端产物(advanced glycation end products,AGEs)形成的影响。结果表明:随着加热温度升高和加工时间延长,AGEs含量呈现先增加后减少的趋势,分别在100℃、60min时达到最大值;初始pH值对AGEs形成具有重要影响,pH7.0时产生AGEs最多,碱性条件次之,酸性条件最少;茶多酚、迷迭香酸、甘草黄酮对AGEs的生成具有显著的抑制作用;金属离子中Fe3+、Fe2+、Al3+、Zn2+和Ca2+对AGEs的形成无显著影响。因此,加工条件如加热时间、加工温度及初始pH值对BSA-Glucose模拟体系中AGEs的形成具有重要影响,且食品级天然抗氧化剂茶多酚、迷迭香酸和甘草黄酮可抑制AGEs形成,金属离子对AGEs形成无影响。     

Maillard reaction products as "natural antibrowning" agents in fruit and vegetable technology

The effects of Maillard reaction products (MRPs), synthesized from a sugar (pentose, hexose, or disaccharide) and either a cysteine-related compound, an amino acid, or a sulfur compound, were investigated on polyphenoloxidase (PPO) activity from apple, mushroom, and eggplant. The optimal conditions for the production of inhibitory MRPs were performed using two-factor and five-level central experimental designs. It resulted that thiol-derived MRPs were highly prone to give rise to inhibitory compounds of PPO activity. Technological assays were also performed to test the efficiency of selected MRPs in the prevention of enzymatic browning in raw and minimally processed fruits and vegetables.     

牛乳加工中非酶蛋白糖基化的研究进展

晚期糖基化终产物(Advance glycationend products,AGEs)是还原糖与蛋白质和核酸在没有酶参与条件下,通过美拉德反应途径形成的稳定聚合物。而这类物质在体内的蓄积可能引发心脑血管疾病和糖尿病等多种疾病。牛乳和奶制品在加工和贮藏过程中均会产生AGEs,从而产生安全隐患。本文综述了牛乳中AGEs形成的途径,各种分析检测手段,以及加工方法、加工温度和贮藏湿度等条件对AGEs形成的影响,进而提出了消除和抑制牛乳中AGEs形成的对策。      

A critical evaluation of fluorescence as a potential marker for the Maillard reaction

During storage of foods and biological systems, fluorescent products are developed through the Maillard reaction, along with the brown pigments. Fluorescent products have been proposed as early indicators of this reaction. The aim of present work was to compare the kinetics of fluorescence and pigment development in order to define adequate early markers. Model glucose–aminoacid systems were prepared in several salts and buffers and stored at 55 °C. Pigment and florescence development was evaluated as a function of time. The results showed that, under unfavourable conditions for the reaction (low pH, presence of retardant salts), fluorescence was detected after important colour changes had occurred. However, under favourable conditions for the reaction (neutral pH, accelerating salts) fluorescent products could be considered as adequate markers because they sensitively reflected early steps of the reaction. Compositional factors and/or environmental conditions are the key factors for defining the performance of fluorescence as an adequate early marker.     

Dietary advanced glycation end‐products: Perspectives linking food processing with health implications

Dietary advanced glycation end products (dAGEs) are complex and heterogeneous compounds derived from nonenzymatic glycation reactions during industrial processing and home cooking. There is mounting evidence showing that dAGEs are closely associated with various chronic diseases, where the absorbed dAGEs fuel the biological AGEs pool to exhibit noxious effects on human health. Currently, due to the uncertain bioavailability and rapid renal clearance of dAGEs, the relationship between dAGEs and biological AGEs remains debatable. In this review, we provide the most updated information on dAGEs including their generation in processed foods, analytical and characterization techniques, metabolic fates, interaction with AGE receptors, implications on human health and reducing strategies. Available evidence demonstrating a relevance between dAGEs and food allergy is also included. AGEs are ubiquitous in foods and their contents largely depend on the reactivity of carbonyl and amino groups, along with surrounding condition mainly pH and heating procedures. Once being digested and absorbed into the circulation, two separate pathways can be involved in the deleterious effects of dAGEs: an AGE receptor‐dependent way to stimulate cell signals, and an AGE receptor‐independent way to dysregulate proteins via forming complexes. Inhibition of AGEs formation during food processing and reduction in the diet are two potent approaches to restrict health‐hazardous dAGEs. To elucidate the biological role of dAGEs toward human health, the following significant perspectives are raised: molecular size and complexity of dAGEs; interactions between unabsorbed dAGEs and gut microbiota; and roles played by concomitant compounds in the heat‐processed foods.     

煎炸过程对棕榈油品质及南美白对虾中 AGEs含量的影响

以煎炸油和煎炸南美白对虾为研究对象,探究煎炸时间及煎炸物料对煎炸油品质的影响;采用液相色谱-质谱联用及荧光技术测定煎炸对虾中晚期糖基化终末产物（AGEs）的含量,探究煎炸过程对煎炸对虾中AGEs生成的影响。结果表明,高温煎炸可加速棕榈油氧化,使其酸值（AV）、p-茴香胺值（p-AnV）、羰基值（CV）显著增加,24 h时达到最大值。煎炸后,对虾水分含量显著降低,脂肪、丙二醛和荧光AGEs含量显著升高,煎炸批次对其无显著影响。煎炸对虾外层丙二醛、荧光AGEs、非荧光AGEs（羧甲基赖氨酸（CML）、羧乙基赖氨酸（CEL）和甲基乙二醛氢咪唑酮（MG-H1））含量显著高于内部,与未煎炸生虾相比除内部CEL含量有所降低外其余均高于未煎炸生虾。随着煎炸批次的增加,煎炸对虾外层CML、CEL和MG-H1含量均逐渐降低,在煎炸第5批时趋于稳定,煎炸第1批时取得最大值,分别为25.37、335.68 mg/kg和468.20 mg/kg,分别为未煎炸生虾的7、4.5倍和16.5倍;煎炸对虾内部CML、CEL和MG-H1含量均先升高后降低,在煎炸第5批时趋于稳定,煎炸第3批时取得最大值,分别为12.56、85.27 mg/kg和204.20 mg/kg,分别为未煎炸生虾的3.5、1倍和7倍。     

甲鱼抗氧化肽对非酶糖基化反应及其终产物的抑制作用

建立体外非酶糖基化蛋白质-还原糖模拟反应体系的基础上,探究甲鱼抗氧化肽对非酶糖基化反应的抑制率(NEG)和晚期糖基化终末产物(AGEs)抑制率的影响.结果表明:甲鱼抗氧化肽能够抑制非酶糖基化反应和晚期糖基化终产物的产生,具有剂量依赖性.当甲鱼抗氧化肽处理蛋白质-还原糖体系21 d时,1.00 mg/mL甲鱼抗氧化肽对N...     

美拉德反应对产品风味品质的影响及其衍生危害物研究进展

在食品加工过程中,美拉德反应虽然对提升食品的风味和品质具有重要作用,但也会衍生一些化学危害物。本文综述了美拉德反应对食品风味和色泽等品质的影响,以及美拉德反应产物的抗氧化和抗突变等特性,同时也探讨了美拉德反应产生的丙烯酰胺(acrylamide,AA)、杂环胺(heterocyclic amines,HAs)和晚期糖基化末端终产物(advanced glycation end products,AGEs)等化学危害物的生成机制、分析和抑制方法。由于3类危害物在食品中的含量较低(ng/g~μg/g)且基质非常复杂,因此其检测均需要采用固相萃取等方法进行分离富集,随后可采用超高效液相色谱串联质谱(ultra performance liquid chromatography-tandem mass spectrometry,UPLC-MS/MS)等方法进行定性定量分析。危害物的抑制主要通过采用更加温和的加工方法、调整工艺参数和添加香辛料及酚类等天然抗氧化物质来实现。