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     

马氏珠母贝酶法抽提物美拉德增香工艺研究

运用美拉德反应改良马氏珠母贝酶法抽提物的风味,以感官评定和美拉德反应程度为指标,采用单因素实验考察了还原糖种类及其配比、还原糖添加量、反应起始pH、反应时间和抽提物含水量对风味的影响;以单因素实验结果为依据,采用正交实验对美拉德反应条件进行了优化。结果表明:葡萄糖3%(w/v)、水分含量70%(w/w)、起始pH6.5条件下反应22min,可以得到头香天然圆润、贝类特征香气突出、体香浓郁丰满、尾香留香持久、整体香气协调统一的调味基料。     

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。     

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.     

枸杞干制过程中褐变反应研究

从宁夏枸杞干制过程中色泽变化入手,测定与色泽变化相关的主要活性物质的变化,研究枸杞干制中褐变反应,以期为枸杞干制生产中的色泽保护技术提供依据。结果表明:随着干制的进行,多酚氧化酶活性逐渐降低,结合枸杞色差值的变化,确定枸杞热风干制前期有酶促褐变的发生。此外,枸杞热风干制后期,不同温度下还原糖和氨基酸态氮的含量都成下降趋势,枸杞色差值逐渐增大,且增速放缓,5-羟甲基糠醛含量逐渐下降,且温度越高越有利于美拉德反应发生。根据各非酶褐变特点,确定了枸杞热风干制后期有美拉德反应褐变存在。      

Formation of pyrazines in hydroxyacetaldehyde and glycine nonenzymatic browning Maillard reaction: A computational study

By considering the formation of pyrazines (C₄N₂H₆ and C₄N₂H₄) as one of the possible final Maillard flavour compounds, Density Functional Theory computations at the standard state have been performed on the proposed mechanisms of glyoxal and glycine in the advanced stage of hydroxyacetaldehyde and glycine nonenzymatic browning reaction under different pH conditions. The results reveal that the basic condition is the most favourable for the production of pyrazines (Pzs), and the aqueous solution is more favourable than that of the gaseous state. The reactions at the isoelectric point of glycine and under neutral conditions are the second and third most favourable for the production of Pzs, respectively. The reaction under acidic conditions is the least feasible for the production of Pzs. Amino acetaldehyde is the most likely precursor of the pyrazine ring in the reaction. Presence of air or oxygen is necessary for the production of 2,3,5,6-tetrahydropyrazine (C₄N₂H₄) from 3,6-dihydropyrazine (C₄N₂H₆). Water is necessary with glyoxal and glycine species for the formation of Pzs and water is produced as a by-product during the formation of Pzs.     

Formation of glyoxal in hydroxyacetaldehyde and glycine nonenzymatic browning Maillard reaction: A computational study

Density functional theory (DFT) computations at the standard state on the proposed mechanisms have revealed that glyoxal (Gox) is one of the most possible intermediates in the hydroxyacetaldehyde (Hald) and glycine nonenzymatic browning Maillard reaction under different pH conditions. By following the total mass balance, the gaseous state reaction has been found as more feasible for the formation of Gox than that of the aqueous solution. Hald + deprotonated glycine reaction under basic condition and Hald + unprotonated glycine reaction under neutral condition have been supposed to be more favorable for the production of Gox than Hald + protonated glycine reaction under acidic condition and Hald + glycine zwitterion reaction at the isoelectric point of glycine. Oxidation of Hald to Gox has been found as more plausible in the gaseous state than the aqueous solution. Oxygen has been found as necessary for the production of Gox from Hald. At the standard state, DFT calculations on the proposed mechanisms have evaluated that unprotonated and deprotonated glycine and glycine zwitterion are feasible for liberating NH₃, whereas protonated glycine has been found as unfeasible. DFT computations at the standard state on the proposed mechanisms have also revealed that the gaseous state Hald + NH₃ reaction is more feasible for the formation of Fald than that of the aqueous solution. Water, which is a by-product, has found as necessary for the initiation of both of Hald + glycine and Hald + NH₃ reactions.     

酒精体系下美拉德反应的研究进展

美拉德反应过程复杂,产物多样,且其反应产物在食品体系中广泛存在,有些产物进入人体后在体内累积并影响健康。目前国内对水相体系中的美拉德反应研究较多,非水相中的研究颇少。然而,我国作为酒类饮料饮用大国,酒精对美拉德反应的影响尚不明确。因而以酒精媒介为切入点,通过研究酒精体系下的美拉德反应从而实现对其有害产物的有效控制,将对提高酒精饮料食品安全发挥重要的作用。从酒精体系对美拉德反应产物的影响和酒精体系中不同的环境因子对美拉德反应的影响两方面的研究进展进行综述。     

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.     

Coordinate contribution of lipid oxidation and Maillard reaction to the nonenzymatic food browning

Lipid oxidation and the Maillard reaction are probably the two most important reactions in Food Science. Both include a whole network of different reactions in which an extraordinary complex mixture of compounds are obtained in very different amounts and produce important changes in food flavor, color, texture, and nutritional value, with positive and negative consequences. This article analyzes the interactions between both reactions, with special emphasis in nonenzymatic browning development, by discussing the influence of lipid oxidation products in the Maillard pathway and vice versa, as well as the existence of common intermediates and polymerization mechanisms in both reactions. The existing data suggest that both reactions are so interrelated that they should be considered simultaneously to understand the products of the Maillard reaction in the presence of lipids and vice versa, and should be included in one general pathway that can be initiated by both lipids and carbohydrates.     

The dual effects of Maillard reaction and enzymatic hydrolysis on the antioxidant activity of milk proteins

The objective of this study was to determine the enhanced effects on the biological characteristics and antioxidant activity of milk proteins by the combination of the Maillard reaction and enzymatic hydrolysis. Maillard reaction products were obtained from milk protein preparations, such as whey protein concentrates and sodium caseinate with lactose, by heating at 55°C for 7 d in sodium phosphate buffer (pH 7.4). The Maillard reaction products, along with untreated milk proteins as controls, were hydrolyzed for 0 to 3 h with commercial proteases Alcalase, Neutrase, Protamex, and Flavorzyme (Novozymes, Bagsværd, Denmark). The antioxidant activity of hydrolyzed Maillard reaction products was determined by reaction with 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt, their 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity, and the ability to reduce ferric ions. Further characteristics were evaluated by the o-phthaldialdehyde method and sodium dodecyl sulfate-PAGE. The degree of hydrolysis gradually increased in a time-dependent manner, with the Alcalase-treated Maillard reaction products being the most highly hydrolyzed. Radical scavenging activities and reducing ability of hydrolyzed Maillard reaction products increased with increasing hydrolysis time. The combined products of enzymatic hydrolysis and Maillard reaction showed significantly greater antioxidant activity than did hydrolysates or Maillard reaction products alone. The hydrolyzed Maillard reaction products generated by Alcalase showed significantly higher antioxidant activity when compared with the other protease products and the antioxidant activity was higher for the whey protein concentrate groups than for the sodium caseinate groups. These findings indicate that Maillard reaction products, coupled with enzymatic hydrolysis, could act as potential antioxidants in the pharmaceutical, food, and dairy industries.     

葡萄糖-甘氨酸美拉德反应产物对脂肪氧合酶的抑制作用研究

以葡萄糖和甘氨酸为原料制备美拉德反应产物（Glu/Gly-MRPs）,研究其对大豆脂肪氧合酶（LOX）的抑制作用以及机理。结果表明:随着反应中甘氨酸浓度、反应初始pH、反应温度和反应时间的增大,Glu/Gly-MRPs的褐变程度加深,pH下降,对LOX的抑制作用增强;当甘氨酸浓度大于0.6mol/L、反应体系初始pH高于8.0、反应温度高于110℃、反应时间长于3h时,MRPs对LOX的抑制率均趋于稳定值（80%¹00%）。Glu/Gly-MRPs对LOX酶促反应的迟滞时间具有延长作用,通过Lineweaver-Burk双倒数法确定Glu/Gly-MRPs对LOX的抑制类型为混合型抑制。      

蚕蛹蛋白酶法水解及美拉德反应改良其产物风味的研究

对多种蛋白酶的酶解效果进行比较,确定了制备酶解脱脂蚕蛹粉短肽和氨基酸的最佳条件,最终确定Alcalase 2.4L和风味蛋白酶的组合为最优方案,酶解液氨基氮含量达到43.17mg/g,总肽氮含量为47.13mg/g,蛋白回收率67.72%,酶解液感官评价值最高。在同等的美拉德反应条件下,Alcalase 2.4L和风味蛋白酶复合酶解的酶解液的香气最为浓郁,腥味被掩盖。     

Study of the Maillard reaction in model systems under conditions related to the industrial process of pasta thermal VHT treatment

Non‐enzymatic browning (NEB) due to the Maillard reaction (MR) was studied in a closed starch/glucose/lysine model system (20 g kg⁻¹ glucose, 10 g kg⁻¹ lysine) in order to analyse conditions favouring reactivity during an industrial process of pasta VHT (very high temperature) thermal treatment. The closed model pastes gave data on the NEB progress during the pasta drying cycle as a function of temperature, time and water activity (a_w). Indicators such as headspace CO ₂ , optical density and colour showed an increase of MR as the initial a_w increased from 0.50 to 0.91. During the initial stages of drying, a combination of high temperatures and high a_w led to the most likely conditions for NEB. © 1999 Society of Chemical Industry     

鸭肉酶解液美拉德反应制备鸭肉香精基料的研究

为制备鸭肉香精基料,以鸭肉酶解液为原料,添加还原糖、盐、维生素以及蒜粉进行美拉德反应。通过单因素实验和正交实验,确定最佳美拉德反应条件:酶解液中加入10%葡萄糖,3%盐,0.7%VB1,0.15%VC和0.1%蒜粉,110℃,自然pH6.87条件下反应30min。在此条件下制得的香精基料液体澄清,淡黄色,具有浓郁的鸭肉香味,令人愉快的香甜气和轻微蒜味,咸鲜味明显、突出,无苦涩味。     

果糖-赖氨酸模型体系美拉德产物不同级分对抑制香蕉酶促褐变相关性质的影响

非硫无毒的抗褐变抑制剂的筛选是目前的研究热点。前期研究显示果糖-赖氨酸模型体系美拉德反应产物对香蕉酶促褐变具有明显的抑制效果。本文研究了分级对该体系产物抑制香蕉酶促褐变相关性质的影响。首先通过超滤、透析等方法将美拉德产物分级为MW<3500 u、MW>5000 u及3500 u5000 u级分的螯合铜离子能力最好,MW<3500 u级分次之。MW<3500 u级分的DPPH?清除能力和抑制香蕉多酚氧化酶能力更佳,分别达46.13%、0.089 mg/mL（IC50）。三种级分对游离酶和酶-底物络合物的抑制常数分别为：KI=0.297 mmol/L,KIS=1.744 mmol/L（MW>5000 u）;KI=0.212 mmol/L,KIS=1.656 mmol/L（3500~5000 u）;KI=0.205 mmol/L,KIS=1.536 mmol/L（MW<3500 u）。说明MW<3500 u级分与游离酶及酶-底物络合物结合更紧密。综上,MW<3500 u的MRPs具有最优的抑制香蕉酶促褐变的能力。     

抑制剂对梨浊汁酶促褐变的控制研究

酶促褐变是梨汁加工和贮藏过程中的主要技术难题之一,其严重影响梨汁的外观、风味等品质。文章以酥梨为试验材料,考察抗坏血酸(AA)、氯化钙、柠檬酸、β-环糊精(β-CD)、乙二胺四乙酸(EDTA)5种抑制剂及其组合对梨浊汁酶促褐变的抑制作用。结果表明:在所选浓度范围内,单一抑制剂对多酚氧化酶相对酶活的抑制强弱顺序为:AA氯化钙柠檬酸β-CDEDTA,当AA、β-CD、EDTA 3种抑制剂结合使用时具有协同作用。通过正交试验设计得出最佳抑制剂组合为:0.10%AA+0.4%β-CD+0.08%EDTA,不仅能够较好地保存果汁中的酚类物质,而且可以使梨汁中多酚氧化酶活性降至未添加防褐变剂时的9.6%,获得色值较好的梨汁产品。     

New functionalities of Maillard reaction products as emulsifiers and encapsulating agents,and the processing parameters: a brief review

Non‐enzymatic browning has been a wide and interesting research area in the food industry, ranging from the complexity of the reaction to its applications in the food industry as well as its ever‐debatable health effects. This review provides a new perspective to the Maillard reaction apart from its ubiquitous function in enhancing food flavour, taste and appearance. It focuses on the recent application of Maillard reaction products as an inexpensive and excellent source of emulsifiers as well as superior encapsulating matrices for the entrapment of bioactive compounds. Additionally, it will also discuss the latest approaches employed to perform the Maillard reaction as well as several important reaction parameters that need to be taken into consideration when conducting the Maillard reaction. © 2016 Society of Chemical Industry     

Inhibition of enzymatic browning in foods and beverages.

Enzymatic browning is a major factor contributing to quality loss in foods and beverages. Sulfiting agents are used commonly to control browning; however, several negative attributes associated with sulfites have created the need for functional alternatives. Recent advances in the development of nonsulfite inhibitors of enzymatic browning are reviewed. The review focuses on compositions that are of practical relevance to food use.