方格星虫酶解物与不同糖Maillard反应特性及其产物特征风味变化

研究不同种类糖（葡萄糖、麦芽糖、木糖和阿拉伯胶）与方格星虫酶解物（enzymatic hydrolysate of Sipunculus nudus,SEH）在一定条件下（120 ℃、120 min）形成Maillard反应产物的吸光度（A420 nm和A294 nm）、pH值、色差、总/游离氨基酸和荧光强度变化,并结合电子鼻对不同反应产物的特征风味进行分析。结果表明,不同种类糖与SEH反应后,产物褐变度增大、黄色加深、亮度变暗、pH值减小;Maillard反应产物的17 种游离氨基酸和总氨基酸含量较SEH均降低,其中8 种苦味氨基酸含量显著降低,改善了酶解液的苦味;SEH与不同糖反应后的荧光强度显著降低且红移,其三级结构发生改变;且不同糖与SEH的反应程度表现为：木糖＞阿拉伯胶＞葡萄糖＞麦芽糖。电子鼻能够较好地区分SEH与不同糖形成的Maillard反应产物特征风味,发现线性判别分析法区分效果优于主成分分析方法,负荷加载分析显示2号和7号传感器在第1主成分上贡献率较大,6号和9号在第2主成分上贡献率较大,表明氨氧化物、甲烷、硫化氢类成分是区别SEH和Maillard反应产物的主要挥发性特征风味。因此,不同种类糖与酶解物Maillard反应特性及其产物特征风味不同,可根据工艺需求选择合适的糖基供体。     

Maillard反应对卵白蛋白稳定性的影响

为了确定Maillard反应对卵白蛋白稳定性的影响,本文研究了Maillard反应卵白蛋白处于酶解、酸性环境、加热、变性剂、反复冻融等不利条件下的理化特点。结果表明Maillard反应抑制了蛋白酶对卵白蛋白的酶解效果。Maillard反应卵白蛋白在p H2~7的范围内,空间结构伸展程度较小。Maillard反应将卵白蛋白的变性温度从71.3℃提高到76.9℃,明显改善了卵白蛋白的热稳定性。6mol·L-1的尿素能够使热处理卵白蛋白和天然态卵白蛋白完全变性,而只能使Maillard反应卵白蛋白部分变性。Maillard反应能够提高卵白蛋白的溶解度,其溶解度经过反复冻融后仍处于较高水平。Maillard反应可以有效提高卵白蛋白稳定性,从而保证卵白蛋白功能性的发挥。     

美拉德反应对食品加工的影响及应用

Maillard反应多年来一直是国内外肉品科学研究的热点之一。Maillard反应是食品加工过程中在还原糖和氨基酸之间发生的复杂的非酶褐变反应。Maillard反应促成某些特有的食品风味和一些烹饪食品颜色的形成。其次,未来有望利用美拉德产物制备一种新型的天然无毒的抗氧化剂。但是,在热处理食品中会造成重要氨基酸的损失,也会使食品的营养价值降低,甚至还会产生毒性物质。本文就Maillard反应反应机理、影响因素及其在食品加工过程中的控制条件和应用做了简要的介绍。     

美拉德反应产物的抗氧化性能研究

通过赖氨酸（甘氨酸）和木糖的美拉德反应可制备具有抗氧化活性的产物。研究了不同反应条件（如时间、pH和反应物摩尔比）对美拉德反应产物（Maillard Reaction Products，MRPs）的抗氧化性能的影响，并与常用食品抗氧化剂特丁基对苯二酚（TBHQ）进行了对比。     

热处理对乳制品营养成分的影响及热处理程度检测方法的研究

热处理对乳制品中的营养成分影响很大，不同的热处理对营养成分的影响不同。介绍了乳制品生产中不同热处理方式对乳中营养成分的影响，并对其营养成分的检测方法进行了综述。     

牛血清白蛋白-葡聚糖接枝改性及机理研究（Ⅰ）

分别采用干热和湿热两种方法制备牛血清白蛋白和葡聚糖Maillard 反应产物,并对其性质进行研究。产物褐变程度及SDS- 聚丙烯酰胺凝胶电泳结果分别表明：干热法反应中Maillard 高级阶段反应程度较弱,反应产物分子量分布较广;湿热法有利于反应向Maillard 高级阶段进行,反应产物分子量分布较为集中。PAS 染色结果证明,两种Maillard反应方法均生成不同接枝程度的糖基化产物,并采用分子排阻色谱分析两种反应体系中Maillard反应产物结构特征。     

玉米纤维胶-乳清分离蛋白Maillard共聚物对姜黄素乳液稳定性和消化特性的影响

以玉米纤维胶（corn fiber gum,CFG）、乳清分离蛋白（whey protein isolate,WPI）为基质制备Maillard反应产物,探究不同热处理时间下CFG-WPI Maillard共聚物对乳液稳定性的影响;并进一步采用不同乳化剂制备包载姜黄素的乳液体系,并探究其消化特性。结果表明,CFG-WPI Maillard共聚物最佳制备条件为加热温度60 ℃、相对湿度79%、反应时间96 h。与单一CFG、WPI以及CFG-WPI混合物相比,CFG-WPI Maillard共聚物制备的姜黄素乳液粒径以及澄清指数较小,且对pH值、Ca2＋浓度等外界环境因子表现出较强的抵抗力,说明CFG-WPI Maillard共聚物制备的乳液稳定性最高。姜黄素乳液消化特性结果表明,CFG的加入有助于减缓脂质水解速率,与单一WPI相比,CFG以及CFG-WPI混合物制备的乳液中姜黄素的生物有效性较高。而对于共聚物构建的乳液体系而言,粒径是影响姜黄素乳液消化特性以及生物有效性的一个重要因素。本研究为了解CFG-WPI Maillard共聚物乳液的形成规律及消化特性提供了一定的参考,同时为CFG的增值利用提供了新途径。     

方格星虫酶解液Maillard反应条件优化及理化特性变化

以方格星虫酶解液(SEH)为原料,以褐变度与感官评分为评价指标,通过单因素实验和正交试验设计优化Maillard反应工艺,并对Maillard反应前后色泽参数、游离氨基酸和总氨基酸含量、荧光强度进行了对比分析。结果表明:最佳Maillard反应工艺条件为半乳糖添加量4%、pH9.0、反应温度130℃和反应时间60 min,在该条件下感官评定达到13.77分。Maillard反应产物(MRPs-SEH)较SEH亮度变暗,色泽加深且更加饱满。MRPs-SEH中的17种氨基酸含量较SEH均显著降低(p0.05)。MRPs-SEH中总氨基酸含量为279.729 mg/g,较SEH降低60.27%,其中Tyr和Met含量较SEH分别减少73.84%、72.98%,说明这两种氨基酸参与Maillard反应的程度较大,His(含量减少44.85%)参与Maillard反应的活性相对较低。MRPs-SEH中鲜味氨基酸在总游离氨基酸中的比例较SEH增加8.26%。Maillard反应改变了SEH中肽链的结构。综合来看,Maillard反应改善了酶解液的色泽与风味,为新型方格星虫调味品的开发提供理论参考。     

酶法水解乳糖与热处理偶联对牛乳Maillard反应的影响

旨在探讨乳糖水解程度及热处理方法与Maillard反应的关系,鲜牛乳用中性乳糖酶处理获得不同水解程度的低乳糖牛乳,然后对牛乳进行不同的热处理,处理后的样本进行Maillard反应程度评价。采用葡萄糖氧化酶法测定不同水解时间的牛乳中葡萄糖质量浓度和乳糖水解率,用高效液相色谱法和紫外分光光度法分别测定水解后牛乳经不同热处理后的糠氨酸和5-羟甲基糠醛(5-hydroxymethylfurfural,5-HMF)含量及牛乳褐变程度的OD值。结果表明,随着乳糖水解时间的延长,牛乳中的葡萄糖含量呈增加的趋势,葡萄糖质量浓度从0.00 mg/100 m L增加到1 721.33 mg/100 m L,但增加趋势逐渐变缓;乳糖水解率从0%增加到70.33%,水解时间2.0 h后的牛乳水解率达到了50%以上。糠氨酸含量呈上升的趋势(P0.05),水解时间在3.0 h以上并经75℃、30 min热处理的牛乳,糠氨酸含量超过了190 mg/100 g pro;水解时间为0.5 h及以上并经75℃、15 s热处理的牛乳,糠氨酸含量超过了12 mg/100 g pro。生鲜牛乳和水解后经75℃、30 min热处理的牛乳,均未检测到5-HMF,水解后经75℃、15 s热处理的牛乳,随乳糖水解时间的延长,牛乳中5-HMF含量增加显著(P0.05)。牛乳的褐变程度随乳糖水解时间显著增加(P0.05),且乳糖酶水解后75℃、30 min热处理的牛乳的褐变程度明显高于75℃、15 s热处理的牛乳。本研究结果说明,乳糖经过酶水解后的牛乳,长时间热处理会加重乳Maillard反应,影响乳的蛋白质品质。     

不同热处理工艺对牛乳中热敏感成分的影响

热处理是保证乳制品质量稳定和卫生安全的重要手段之一,牛乳在热处理过程中会发生美拉德反应、乳糖异构化和蛋白质变性等多种化学变化,且反应程度与热处理强度密切相关。文中以纯鲜生乳为材料,经巴氏、超巴氏和超高温瞬时杀菌(UHT)等热处理后,分析检测牛乳中主要热敏感成分的变化。结果表明:随着热处理强度的提高,牛乳中的糠氨酸含量呈指数关系增加,纤溶酶活则逐渐下降;热处理强度不同导致乳清蛋白各组分的变性程度也不同,其中β-LgB和BSA对热最敏感,β-LgA其次,α-La的耐热性最强;热处理温度越高,时间越长,牛乳中VB1和VB6的损失率也就越高。根据牛乳中热敏感成分含量或活性在热处理过程中的的变化规律,可以将糠氨酸、α-乳白蛋白和纤溶酶活等作为牛奶受热程度的指示物,从而更好的指导实际生产和维护消费者权益。     

热处理对牛乳美拉德反应程度及挥发性成分的影响

以原料乳及不同热处理程度的15 种牛乳样品为研究对象，通过分析典型美拉德产物糠氨酸和5-羟甲基糠醛的含量以反映不同热处理牛乳的美拉德反应程度，同时采用顶空固相微萃取-气相色谱-质谱（headspace solid-phase microextraction-gas chromatography-mass spectrometry，SPME-GC-MS）和电子鼻解析不同热处理的牛乳中挥发性成分的变化规律。结果表明：热处理程度越大，美拉德反应越剧烈，美拉德产物糠氨酸和5-羟甲基糠醛的含量在热处理温度高于120 ℃或热处理时间高于15 s时急剧增加。电子鼻通过主成分分析可知，热处理时间相同时，不同热处理温度的牛乳样品间气味差异显著。SPME-GC-MS结果表明：120 ℃/5 s和120 ℃/15 s热处理的牛乳风味相近，且热处理强度越大，风味物质种类增加越多，其中醛类、酮类和酯类相对含量增加明显，部分酸类相对含量明显减少。本实验明确不同热处理方式对牛乳美拉德反应程度及其对牛乳风味的影响，具实际生产指导意义。     

The FAST index – A highly sensitive indicator of the heat impact on infant formula model

Infant formulas are highly sensitive to the Maillard reaction during manufacturing, while this reaction induces significant loss in protein nutritional value and safety. The indicators mostly used to monitor the reaction during heat treatment are furosine, carboxymethyllysine and hydroxymethylfurfural, but analysis of these molecules is time-consuming and expensive. The FAST method, based on simple fluorescence measurements on clear milk supernatant, is a good alternative for Maillard reaction monitoring in milk products.     

Photoacoustic analysis of some milk products in ultraviolet and visible light

The research reported here demonstrates the possibility of using photoacoustic spectroscopy for milk product analysis. Milk products including yogurt, cheese, and market milk were analyzed in the ultraviolet visible range. A strong absorption peak was present at 280 nm for all the products. Relationship was linear between relative protein concentration of skim milk and the photoacoustic signal at 280 nm (r2 greater than .99). Powdered milks, prepared from skim milk that had been subjected to different heat treatments before drying, were analyzed, and a second absorption peak at 335 nm was noted for milks subjected to high heat treatment prior to the drying process. This second absorption peak appears associated with Maillard reaction products. Analysis of stored UHT heat-treated milk and infant formulas showed a similar peak at 335 nm. The results suggest that the Maillard reaction is initiated during UHT treatment of milk, and associated pigments develop only during storage. The presence of the 335-nm band in the photoacoustic spectra of infant formulas is considered as the result of heat sterilization. It is anticipated that as photoacoustic spectroscopy becomes more common, its usefulness in the milk industry, in particular, and in food science, in general, will increase.     

复原乳鉴别指标探讨

选择适宜的鉴别指标,确定并完善复原乳的鉴定方法,不但可为质量监督检验机构的检测和监督工作提供技术支持．而且可有效保护消费者的利益。可以通过检测牛奶在长时间贮藏过程中产生的荧光物质．或检测牛奶中脂肪酸组成分的变化来鉴别鲜奶与复原乳,但难以排除某些干扰因素的影响。近年来复原乳鉴定指标的研究热点主要集中在奶制品经热处理后其中的热损害产物。有两种化学反应产物可用来评价：（1）降解产物：热不稳定组分的降解、变性、失活,如乳清蛋白或酶;（2）新形成物质：如乳果糖或美拉德反应的产物。目前国际上通常用糠氨酸和乳果糖作为评估热处理和贮存对奶制品质量影响的指标。然而各指标也不可避免的存在一定的局限性,因此可能需要不止一个指标来进行综合评价。     

Chemical methods and techniques to monitor early Maillard reaction in milk products; A review

Maillard reaction is an extensively studied, yet unresolved chemical reaction that occurs as a result of application of the heat and during the storage of foods. The formation of advanced glycation end products (AGEs) has been the focus of several investigations recently. These molecules which are formed at the advanced stage of the Maillard reaction, are suspected to be involved in autoimmune diseases in humans. Therefore, understanding to which extent this reaction occurs in foods, is of vital significance. Because of their composition, milk products are ideal media for this reaction, especially when application of heat and prolonged storage are considered. Thus, in this work several chemical approaches to monitor this reaction in an early stage are reviewed. This is mostly done regarding available lysine blockage which takes place in the very beginning of the reaction. The most popular methods and their applications to various products are reviewed. The methods including their modifications are described in detail and their findings are discussed. The present paper provides an insight into the history of the most frequently-used methods and provides an overview on the indicators of the Maillard reaction in the early stage with its focus on milk products and especially milk powders.     

Effect of heating on Maillard reactions in milk

Heated milk is subject to the Maillard reaction; lactose and lysine residues in milk proteins (mainly casein) are the reactants. An overview is given of the early, advanced and final stages of the Maillard reaction as it occurs in milk. The early Maillard reaction is confined to the formation of the protein-bound Amadori product lactulosyllysine. Breakdown of the Amadori product leads to formation of all kinds of advanced Maillard reaction products such as lysylpyrraline, pentosidine, hydroxymethylfurfural, (iso)maltol, furfurals and formic acid. The content of these compounds in heated milk is, however, very low (with the exception of formic acid), and does not correspond to the breakdown of Amadori product in quantitative terms. The final stage, in which melanoidins (brown pigments) are formed and protein polymerization occurs, is largely unknown from a chemical point of view, let alone quantitatively. The conclusion can only be that not all important compounds are yet identified. Some experimental data for heated milk are given to illustrate the various stages of the Maillard reaction in heated milk. A kinetic analysis of the Maillard reaction is difficult because it is such a complicated reaction with many parallel and consecutive steps; in addition, one of the reactants, lactose, is also subject to another reaction, namely isomerization followed by degradation. The kinetics can be tackled by kinetic, multiresponse modelling, and this approach is illustrated. It appears that the temperature dependence of the (early) Maillard reaction is lower than for the simultaneously occurring isomerization reactions of lactose. The use of several components formed in the Maillard reaction to evaluate the heat intensity given to milk is discussed.     

热处理对生鲜乳及复原乳蛋白质体外消化特性的影响

通过体外模拟消化的方法对不同热处理的牛乳样品进行检测,研究热处理对鲜牛乳及复原乳营养价值的影响。通过聚丙烯酰氨凝胶电泳、尺寸排阻高效液相色谱、扫描电镜及质谱分析等多种方法进行检测。结果表明:经过胃液消化后,牛乳中的部分蛋白被消化,其中酪蛋白消化最为明显,鲜牛乳中酪蛋白在胃液中的消化水平高于其他热处理样品;而经过肠液消化后,牛乳中蛋白消化完全,生成游离氨基酸及小肽。乳中蛋白质经消化主要生成分子质量低于1 500 Da的肽段,易于人体消化吸收。通过扫描电镜可以看出,热处理程度越大,乳蛋白变性,发生聚集现象,粒径增大,其中加热复原乳的粒径较其他乳制品大;通过质谱检测及高效液相色谱分析,热处理程度越大,蛋白质美拉德反应程度升高。     

The impact of microwave heating of infant formula model on neo-formed contaminant formation, nutrient degradation and spore destruction

Heat treatment of milk results in the development of a large range of Maillard products, especially in infant formulas due to their high content in Maillard reaction substrates. The Maillard reaction should be minimized because some of those products, called neo-formed contaminants (NFC), are currently suspected of promoting deleterious health effects. The objective of this work was to study the impact of microwave heating on the formation of Maillard compounds, degradation of nutrients and destruction of spores of an infant formula model. An infant formula model based on pure-whey proteins was used as experimental model. A spore suspension of Geobacillus stearothermophilus was prepared and inoculated in the formulated milk before microwave treatment. The treatment was performed on a laboratory device running at 2450 MHz and equipped with a magnetron (power range 0-1860 W) and the temperature was controlled by three optical fibers. Heating kinetics were established at several microwave specific powers (5, 7, 10, 12 W/mL). The impact of the treatment on NFC formation was evaluated by 3 indicators: the FAST index (indicator of global advancement of Maillard reaction), carboxymethyllysine (CML) and furosine. All these NFC indicators seemed to follow an exponential model as a function of time. The thermal sensitive nutrient vitamin C was chosen as indicator of the nutritional quality. Like in conventional heating, an exponential model was observed for spore inactivation and vitamin C degradation. Furthermore, laws similar to those used for conventional heating could be used to express heat resistance regarding germ viability, vitamin C concentration and Maillard products. As a result, D and z-values relative to specific microwave powers were determined for each indicator. Finally, it was found that the best way to minimize NFC formation and nutrient degradation was to use high specific power for a short time, similar to what is obtained with the UHT process for conventional heating.