The effect of pH on the formation of maillard-derived aroma volatiles using a cooked meat system

The effect of pH on the formation of volatile compounds was investigated using minced beef in which the pH was adjusted within the range 4.0–5.6, by the addition of hydrochloric acid before cooking. The strong buffering capacity of the meat ensured that the pH did not vary during heating. Volatiles were analysed using headspace concentration and gas chromatography-mass spectrometry. The total quantity of volatile compounds increased as the pH decreased. A number of furanthiols and their oxidation products were preferentially formed at acid pH; some of these compounds had strong meaty aromas. The formation of other heterocyclic compounds such as thiazoles and pyrazines were favoured by higher pH.     

Interaction of lipid in the maillard reaction between cysteine and ribose: The effect of a triglyceride and three phospholipids on the volatile products

The inclusion of phospholipid in the Maillard reaction between cysteine and ribose is known to modify the volatile aroma compounds produced. The contributions made to the headspace volatiles by 60 major products of this reaction have been compared for four different lipids and their effect on aroma quality noted. The results described demonstrate marked dissimilarities between the behaviour of the four lipids. The most noticeable distinction was between the effect of triglyceride and the three phospholipids, but there were also variations in the way that each of the three phospholipids participated in the Maillard reaction. As well as displaying marked differences in volatile products, reaction mixtures containing the four lipids possessed distinct aroma characteristics; the phospholipids containing phosphatidylethanolamine conferred the most meat-like odour. These differences appear to be caused by the dissimilar fatty acid compositions and polar moieties. Thus this study underlines the importance of lipid interaction in the Maillard reaction for the formation of flavour.     

基于木糖母液美拉德反应及其产物挥发性成分研究

木糖母液是玉米芯或蔗渣酸水解的副产物,含大量的糖类,但由于分离困难,限制了其在工业中的大规模使用。以废弃的木糖母液为研究对象,将其与L-谷氨酸进行美拉德反应,采取正交试验确定最佳反应条件,并对其反应产物的挥发性成分采用气相色谱-质谱（GC-MS）法进行分析测定。试验结果表明：当反应温度为105 ℃、反应时间为3.0 h、pH值为12时,吸光度值为1.910,在此条件下,木糖母液美拉德反应褐变程度最强;通过对产物进行气相色谱-质谱联用仪分析,共鉴定出91种木糖母液美拉德反应产物挥发性成分,主要有醇、酮、酸、酯及醚五大类。     

酪蛋白-木糖体系美拉德反应产物的抗氧化活性

研究评价了由酪蛋白-木糖模拟体系产生的美拉德反应产物的抗氧化活性,考察了反应过程中体系的pH、褐变和中间产物的变化,并测定了美拉德反应产物对金属离子(Cu2+和Fe2+)的螯合能力、自由基清除能力(.OH、DPPH.和ABTS.)以及其还原能力。结果表明,模拟体系的酸度和褐变均随反映的进行而逐渐增加,中间产物在反应初期大量形成;美拉德反应产物对Fe2+的螯合能力要明显强于对Cu2+的螯合能力;美拉德反应产物对DPPH.和ABTS.具有较强的清除作用,而对.OH的清除作用较弱;美拉德反应产物的还原能力随反应时间的延长而逐渐增大。     

Significant influence of particular unsaturated fatty acids and pH on the volatile compounds in meat-like model systems

The present study aimed to investigate the effects of particular unsaturated fatty acids and pH on volatile compounds in the meat-like model systems containing 21 amino acids and ribose. We have chosen oleic acid (C18:1n-9), linoleic acid (C18:2n-6) and linolenic acid (C18:3n-3) for the present investigation. The effect on the volatile compounds was evaluated at two different pH 5.5 and 6.2. The addition of C18:2n-6 and C18:3n-3 to the Maillard reaction mixtures inhibited the formation of many Maillard compounds or produced in low amount. Whereas, the addition of C18:1n-9 resulted in an increase in the amount of many Maillard compounds. The thiols and thiophenes were preferentially formed at pH 5.5 whereas pyrazines were preferentially favored at pH 6.2. Based on our results, it is suggested that a high level of C18:2n-6 and C18:3n-3 in meat probably causes an undesirable flavor. The pH value of 5.5 was found to be ideal for the formation of volatile compounds associated with desirable flavor of meat.     

Effects of lard on the formation of volatiles from the Maillard reaction of cysteine with xylose

BACKGROUND: The presence of lipid oxidation products in the Maillard reaction pathway is of particular interest today. The objective of this study was to investigate the effect of lard and its oxidation products on the formation of volatiles from cysteine and xylose model systems. RESULTS: Headspace volatiles generated in reaction mixtures were examined by solid‐phase microextraction in combination with gas chromatography‐mass spectrometry. The addition of lipid had a suppressing effect on most of the sulfur‐containing compounds derived from the reaction between cysteine and xylose, especially for 2‐methyl‐3‐furanthiol, 2‐furanmethanethiol, 2‐methylthiophene, and 3‐methylthiophene. One of the intermediates—furfural—was also formed in much lower concentration when lard was present. In addition, cysteine and xylose modified lipid oxidation pathways, so that lipid‐derived alcohols, alkylfurans and aliphatic acids were formed rather than aldehydes. Compared with the lard heated alone, most aldehydes were formed at lower levels in the lard‐containing reaction mixtures, and several aldehydes including hexanal, heptanal, (2E)‐heptenal and (2E,4E)‐heptadienal were absent. CONCLUSION: The addition of lipid was inhibitory to the formation of most sulfur‐containing compounds in the Maillard reaction. Furthermore, Maillard reaction products influenced the formation of products from lipid oxidation. Copyright © 2011 Society of Chemical Industry     

pH对模型体系Maillard反应产物抗氧化性的影响

以ABTS（2,2’-联氮-二-（3-乙基-苯并噻唑啉-6-磺酸））自由基清除能力和还原能力为抗氧化性评价指标,研究了葡萄糖-酪氨酸和葡萄糖-组氨酸两种模型体系在不同初始pH下（pH=5、7、9）反应生成的Maillard反应产物（MRPs）的抗氧化性。结果表明:对于葡萄糖-酪氨酸体系,MRPs的ABTS自由基清除能力和还原能力均在碱性条件下最大;对于葡萄糖-组氨酸体系,MRPs的ABTS自由基清除能力在碱性条件下最大,还原能力在酸性条件下最大;相关性分析显示来自两种体系的MRPs的抗氧化性与紫外吸收（A280nm）和棕色化程度（A420nm）均呈一定的线性相关性,表明紫外可见吸收可用来指示葡萄糖-酪氨酸/组氨酸体系MRPs的抗氧化能力的变化规律。      

美拉德反应产物的抗突变作用

美拉德反应是食品制备、加工和贮存过程中发生的非酶褐变反应，褐变的发生对产品质量有很大影响，从食品卫生学的角度来看，有些产物对人体健康有极大的危害。本文讨论的是美拉德反应产物有益的一面，即其抗突变的效果。     

木糖与甘氨酸美拉德反应产物抗氧化性能的研究

以木糖和甘氨酸为底物,控制不同的物质的量(木糖与甘氨酸物质的量之比分别为1∶0.1、1∶0.2、1∶0.4)进行美拉德反应,制备了三种不同的美拉德反应产物,并通过还原能力、清除H2O2能力、清除羟基自由基(.OH)、清除超氧阴离子自由基(O2-.)、清除亚硝酸根(NO2-)等体系研究了美拉德反应产物的抗氧化性能。结果表明,三种反应产物均具有较强的抗氧化能力,随着反应产物浓度的增加,抗氧化能力增强;三种产物的还原能力和清除O2-.的能力相当;木糖与甘氨酸物质的量之比为1∶0.2的美拉德反应产物清除H2O2、.OH和NO2-的能力要强于物质的量之比为1∶0.1和1∶0.4的反应产物。     

Effects of supercritical carbon dioxide on volatile formation from Maillard reaction between ribose and cysteine

BACKGROUND: Supercritical carbon dioxide (SC‐CO₂) technology is being used in an increasing number of food‐manufacturing applications; however, its effect on the Maillard reaction is not well studied. The objective of this study was to investigate the effect of SC‐CO₂ treatment (140 °C, 40 MPa) on the Maillard reaction of an aqueous ribose–cysteine model system under varying pH conditions (5.6, 7.0 and 8.0), with emphasis on the formation of volatile compounds. RESULTS: SC‐CO₂ had a suppressing effect on the browning stages of the reaction under acidic and neutral pH conditions, while it appeared to have an accelerating effect at pH 8.0. Over 70 volatile compounds were positively identified from the headspace of the model system by gas chromatography–mass spectrometry. The volatiles were dominated by sulfur‐containing compounds including thiophenes and fused bicyclic sulfur‐containing compounds under all experimental conditions. Several compounds, including 2‐methyl‐3‐furanthiol, 2‐furanmethanethiol, 3‐thiophenethiol, and 2‐methyl‐3‐thiophenethiol, and one of the intermediates, furfural, were generated in much higher amounts in the SC‐CO₂‐treated samples, especially at alkaline and neutral pH values. CONCLUSION: SC‐CO₂ treatment was inhibitory to the formation of most volatiles in the Maillard reaction, but enhanced the formation of some intermediates and well‐known meaty flavoured compounds. Copyright © 2007 Society of Chemical Industry     

蛋清蛋白-木糖美拉德反应产物膜的特性及其膜包裹对核桃仁酸价的影响

蛋清蛋白具有丰富的营养价值和良好的成膜性,是可食用膜的重要材料。但蛋清蛋白膜的阻湿性较差,因此通过美拉德反应对蛋清蛋白进行了糖基化改性,用蛋清蛋白-木糖美拉德反应产物制备膜,试图改善蛋清蛋白膜的阻湿性。首先研究了不同糖类、不同pH、不同加热温度以及不同木糖浓度对蛋清蛋白-木糖美拉德反应进程的影响。并进一步制备蛋清蛋白-木糖美拉德反应产物膜,研究其成膜性以及水蒸气透过率。最后用蛋清蛋白-木糖美拉德反应产物膜对核桃仁进行包裹,考察其对核桃仁酸价的影响。结果表明,蛋清蛋白-木糖美拉德反应产物膜与蛋清蛋白膜相比,水蒸气透过率降低了24%。与未包膜组相比,经过蛋清蛋白-木糖美拉德反应产物包膜的核桃仁酸价降低约30%。蛋清蛋白-木糖美拉德反应产物与蛋清蛋白2种膜包裹对抑制核桃仁脂质过氧化的效果没有明显差别。     

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。     

The kinetics of Maillard reaction in lactose-hydrolysed milk powder and related systems containing carbohydrate mixtures

The kinetics of Maillard reaction in lactose-hydrolysed skim milk powder and related systems containing carbohydrate mixtures were analysed. The effect of the increase of water activity and temperature during storage of the commercial product was also evaluated. In systems with two and three carbohydrates, a marked decrease of the reaction rate was observed when monosaccharides were partially replaced by lactose, notwithstanding the fact that the former still remained in a higher proportion than lysine. The rate of available lysine loss in lactose-hydrolysed milk was mostly affected by the presence of galactose. The reaction rate constants at a_w 0.52 and at 37 and 50 °C were higher than at a_w 0.33. However, no significant differences were observed at 60 °C. Temperature is the most important factor to be controlled in order to minimise nutritional deterioration during storage.     

反应温度和时间对抗坏血酸/精氨酸Maillard反应体系中挥发性化合物形成的影响

采用顶空固相微萃取-气相色谱-质谱联用技术对抗坏血酸/精氨酸反应体系在不同反应温度和时间下的产物进行鉴定,共鉴定出包括吡嗪、醛、呋喃、醇和吲哚在内的24种化合物,其中14种吡嗪化合物为主要香味化合物。考察了反应温度和时间对产物特别是对吡嗪化合物的影响。结果表明,随着反应温度的升高和反应时间的延长,吡嗪类化合物的总量均增加;其中,随反应温度的升高,相对其他吡嗪化合物2-乙基-6-甲基吡嗪、3-乙基-2,5-二甲基吡嗪的量明显增加;随反应时间的延长,2-乙基-6-甲基吡嗪的量明显增加。     

美拉德反应产物抗氧化性能研究进展

综述了国内外美拉德反应产物抗氧化性能的研究进展,并对其抗氧化活性的机理以及反应条件对抗氧化能力的影响进行了一些探讨。