大豆肽-木糖美拉德反应体系中肽的降解与交联规律研究

通过研究大豆肽-木糖美拉德反应体系中不同的肽段随时间的变化,探讨大豆肽在美拉德反应中的降解与交联规律,以指导美拉德肽的有效制备。结果表明,在美拉德反应中,还原糖对肽的降解和交联起促进作用,当反应时间超过1.0h时,游离氨基酸含量升高,糖促进肽的降解作用突出。随着反应时间的延长,>5000Da和<1000Da的肽段降解程度逐渐增加,当时间超过2.0h时,>5000Da肽段含量增加,糖肽交联作用明显,而1000～5000Da肽段在反应达1.0h时增加3.86%,随后缓慢降低。     

美拉德反应对南极磷虾酶解液中非挥发性物质的影响

以南极磷虾酶解液和木糖进行美拉德反应,研究美拉德反应后,酶解液和美拉德产物中游离氨基酸、肽分子量分布、无机离子含量等非挥发性物质的变化规律。结果表明,美拉德反应后,酶解液中多数游离氨基酸含量显著降低,其中亮氨酸、精氨酸、组氨酸、异亮氨酸、半胱氨酸损失率分别为34.18%、16.75%、16.67%、16.10%、12.37%;酶解液肽段中451 Da～1 450 Da组分具有较高的美拉德反应活性;无机离子含量以Na+含量最高;脂肪酸组成呈现减少趋势,减少组分以多不饱和脂肪酸为主。     

温度对鸡骨酶解液-木糖美拉德反应产物中非挥发性物质的影响

以鸡骨酶解液和木糖进行美拉德反应,研究不同温度下鸡骨酶解液-木糖美拉德反应产物中游离氨基酸和肽段等非挥发性物质的变化规律。结果表明,随着温度的增加,鸡骨酶解液-木糖美拉德反应产物中多数游离氨基酸含量显著降低,其损失率总体上与温度呈现正相关,其中丙氨酸、色氨酸、苏氨酸和亮氨酸等损失率高达50%以上;温度越高,鸡骨酶解液中各肽段更易发生美拉德反应,其中1 000~2 000 Da和500~1 000 Da组分具有较高的美拉德反应活性。     

不同分子质量大豆蛋白和鸡肉酶解物的美拉德反应产物风味特征分析

为了研究不同分子质量的肽在美拉德反应后的风味特征,以大豆蛋白和鸡肉为原料酶解得到蛋白酶解物。对酶解物超滤分离得到小于1000Da、1000~5000Da和大于5000Da的不同分子质量肽组分,并对大豆蛋白和鸡肉酶解物完全酸水解得到复合氨基酸。在得到的肽段和氨基酸中添加一定量的木糖,构建美拉德反应模型。对美拉德反应产物感官特性进行评价,再采用气相色谱-质谱联用、高效液相色谱对挥发性和不挥发性化合物进行分析。结果表明:在2种不同蛋白来源的酶解物的美拉德反应产物中,共鉴定出挥发性化合物69种,其中吡嗪和呋喃硫醇等肉香味化合物的含量最高。统计分析表明:不同分子质量的肽和游离氨基酸的挥发性化合物存在明显差异。小于1000Da的肽在美拉德反应过程促进了吡嗪类化合物的生成,其中包括了吡嗪、5-甲基-2-乙基吡嗪、2,5-二甲基-3-乙基吡嗪、三甲基吡嗪、2-乙酰基吡咯等挥发性化合物。与肽相比,游离氨基酸有利于含硫化合物如呋喃硫醇类和噻吩类物质的生成。有29种挥发性化合物的相对气味活性值大于1。偏最小二乘回归研究了气味化合物与感官评价之间的相关性,发现小于1000Da的肽与基本的肉味和浓厚味密切相关,而大于5000Da的肽与苦味和焦煳味密切相关。在美拉德反应后,分子质量大于5000Da的肽数量显著减少；分子质量1000~5000Da的肽降解可以补充消耗的游离氨基酸；分子质量小于1000Da的肽容易发生交联和聚合现象而含量增加,其产物对风味的影响明显增强,能更好地体现基本的肉味、鲜味和浓厚味。希望研究可以为利用蛋白质酶解物生产美拉德反应产物的应用提供理论支撑和指导。     

海鲜菇美拉德肽的制备及其风味特性研究

以海鲜菇（Hypsizygus marmoreus）蛋白肽为原料,采用响应面法分析优化海鲜菇美拉德肽制备工艺,并通过褐变程度、产物分子量分布、感官评价、电子舌及超滤等特征性指标和评价手段,明确美拉德反应对海鲜菇蛋白肽风味特性的影响。结果表明,海鲜菇美拉德肽的最佳制备条件为葡萄糖与D?木糖质量比4∶1、反应温度110 ℃和反应时间56 min。与海鲜菇蛋白肽相比,制备的海鲜菇美拉德肽咸味强烈,并伴有鲜味产生,整体接受度好,在294 nm和420 nm 下吸光值显著增加,并推测分子量大于180～500 Da 的组分可能为美拉德反应的主要活性肽段。超滤结果表示,海鲜菇美拉德肽呈咸鲜味的肽分子量主要集中在500 Da 以下。该研究结果证明美拉德反应可有效提升海鲜菇蛋白肽的咸鲜味,使其风味层次更加丰富,可为扩展可替代钠盐的新型食用菌调味领域的研究和应用提供理论基础。     

木瓜蛋白酶水解鸡肉蛋白及其产物氨基酸分析研究

本文采用木瓜蛋白酶水解鸡肉蛋白研究其降解规律及酶解产物氨基酸组成。研究表明:热处理鸡肉蛋白不利于酶解;整个酶解过程中,可溶性氮、氨态氮含量呈增加趋势,但4h后增势变缓,而肽含量在水解8h达到最大值;肽分子量分布图显示大部分不溶性蛋白和分子量大于10000Da肽段在酶解4h后已经变为可溶性多肽和氨基酸,分子量在5000～10000Da间肽段酶解24h后仍大量存在,分子量在3000～5000Da间以及小于3000Da的肽占总肽量比值在整个酶解过程中呈增加趋势。与原料蛋白氨基酸组成比较表明采用木瓜蛋白酶水解鸡肉蛋白能显著提高其营养价值。     

大豆肽的制备及其美拉德反应产物特性研究

本文以高温大豆粕为原材料,模拟酱油制曲工艺,通过发酵和酶解技术制备大豆肽,研究大豆肽及其美拉德反应产物的特性。通过比较其蛋白质回收率、DPPH自由基清除率等抗氧化指标、褐变程度及其肽分子量分布情况,深入研究了发酵酶解工艺和酶解时间对大豆肽及其美拉德产物抗氧化特性的影响。研究发现,发酵和酶解处理均可显著提升高温大豆粕的蛋白质回收率和抗氧化活性,在酶解时间为24 h时大豆粕的回收率达到最大值77.21%,此时大豆粕酶解产物的DPPH自由基IC50值和还原力(A700)分别为0.77 mg/m L和0.16。而美拉德反应则可以进一步提升大豆粕酶解产物的抗氧化活性。另外美拉德反应过程中分子质量较大的组分热降解反应比较剧烈,而小分子寡肽则比大分子多肽具有更高的美拉德反应活性。     

温度对金带细鲹鱼肉水解物美拉德反应及其产物抗氧化性的影响

采用金带细鲹鱼肉蛋白为研究对象,以pH值、中间产物、褐变程度、游离氨基酸含量及抗氧化活性为检测指标,研究温度(100,120℃)对金带细鲹鱼肉蛋白水解物美拉德反应及其产物抗氧化活性的影响。结果表明:当反应温度为120℃时,反应体系的pH值、中间产物(A294nm)、褐变程度(A420nm)及游离氨基酸含量,随着美拉德反应时间的延长与100℃相比变化更加显著,反应产物的还原力和DPPH自由基清除率大幅度提高,而羟自由基清除率和Fe2+螯合能力下降明显。     

鱼肉蛋白-D-木糖MRPs抗氧化活性的研究

为分析实际体系美拉德反应产物(MRPs)的抗氧化活性,采用4种不同品种鱼肉(鲢鱼、草鱼、鲫鱼和鲤鱼)蛋白与D-木糖建立实际体系进行美拉德反应,反应产物通过恒温油浴加热制备,以DPPH自由基(DPPH·)作为美拉德反应产物抗氧化活性的测定指标。单因素试验考察加热温度、时间、p H及反应底物质量比对美拉德反应的影响,优化出MRPs抗氧化活性最强的鲫鱼蛋白-D-木糖为实际反应体系。均匀试验结果表明,鲫鱼蛋白-D-木糖实际体系MRPs对DPPH自由基的清除率最高,抗氧化活性最强。且最佳工艺条件为:反应时间70 min,温度136℃,初始p H 12.0及反应底物质量比(鲫鱼蛋白∶D-木糖)为3∶1。     

不同分子质量段小麦面筋蛋白酶解液对美拉德反应物风味的影响

用超滤法将小麦面筋蛋白酶解液根据分子质量大小分为大于10 ku(M1),5～10 ku(M2),3～5 ku(M3),1～3 ku(M4),小于1 ku(M5)5个组分,研究这5个组分对美拉德反应产物风味的影响。结果表明,美拉德反应产物的主要风味物质是醛类,并且高分子量段美拉德反应产物中高级醛种类较多,而游离氨基酸和小分子寡肽参与美拉德反应主要生成吡嗪类风味物质。分子质量段为3～5 ku(M3)的膜分离组分,其美拉德反应产物鲜味氨基酸含量较高,苦味氨基酸含量较低,鲜味突出,醇厚味明显。     

Effect of xylose on the molecular and particle size distribution of peanut hydrolysate in Maillard reaction system

BACKGROUND: The Maillard reaction is a complex series of reactions between reducing sugars and amino groups. Changing any of reaction parameters would alter the reaction pathway. This study investigated the effect of xylose concentration on the molecular and particle size distribution of Maillard reaction products (MRPs) derived from peanut hydrolysate and xylose to discuss their formation mechanism. RESULTS: Molecular weight and particle size distribution analyses indicated that both peptide degradation and peptide cross‐linking occurred during the Maillard reaction. Heat treatment would make the high‐molecular‐weight peptides degrade into low‐molecular‐weight peptides and free amino acids. Maillard reaction increased the molecular weight and particle sizes of products as the xylose concentration increased from 1% to 4%. CONCLUSION: The study shows that both peptide degradation and peptide cross‐linking occurred during the Maillard reaction. The thermal degradation product (TDP) and MRPs had significantly different molecular size distribution, and the particle size distribution of TDPs and MRPs had similar change tendency to that of the molecular size distribution. These would provide an insight into the formation mechanism of MRPs. Copyright © 2011 Society of Chemical Industry     

Temperature effect on the non-volatile compounds of Maillard reaction products derived from xylose–soybean peptide system: Further insights into thermal degradation and cross-linking

Solutions of soybean peptide with or without xylose were heated over a range of temperatures (80–130 °C) for 2 h to investigate the characteristics of Maillard reaction and the effect of temperature on amino acids and peptides. It was found that both peptide degradation and peptide cross-linking occurred in the Maillard reaction. The critical temperature for peptide degradation was 100 °C, and above it, peptides degraded quickly in thermal degradation system. However, in Maillard reaction system, peptides cross-linked rapidly when the temperature reached 110 °C. Bitter amino acids and peptides below 1000 Da decreased 18.44% and 28.49%, respectively, after Maillard reaction at 120 °C. On the other hand, peptides between 1000 and 5000 Da were increased significantly, nearly doubled compared to its initial hydrolysates after Maillard reaction at 120 °C. Moreover, the increase of macromolecule products was also accompanied with severe browning and pH decrement.     

Effects of temperature and pH on angiotensin-I-converting enzyme inhibitory activity and physicochemical properties of bovine casein peptide in aqueous Maillard reaction system

The purpose of this study was to evaluate the impact of temperature and pH on aginotensin-I-converting enzyme (ACE) inhibitory activity, free amino group, browning intensity, fluorescence intensity and molecular weight distribution of galactose-bovine casein peptide (BCP) Maillard reaction products (MRPs). With increased heating temperature and pH, browning intensity of Galactose-BCP MRPs increased, while free amino groups of Galactose-BCP MRPs decreased. The fluorescence intensity of Galactose-BCP MRPs reached its maximum value at 100 °C and thereafter gradually decreased, while fluorescence intensity of Galactose-BCP MRPs showed the maximum value at pH 10.0 and thereafter gradually decreased. Size exclusion chromatography of Galactose-BCP MRPs indicated molecular rearrangements and production of new smaller molecules as a function of the heating temperature and pH. Galactose-BCP MRPs had the lowest angiotensin-I-converting enzyme (ACE) inhibitory activity at 120 °C. BCP lost 29.13% ACE inhibitory activity at pH 12.0 by Maillard reaction with galactose. High temperature and alkaline condition of Maillard reaction lead to the loss of ACE inhibitory activities and changes of characteristics of bovine casein peptides.     

酶法及美拉德反应改进鸡肉蛋白功能性质的研究

利用不同单酶酶解鸡胸肉,制得的酶解液和木糖进行美拉德反应,考察不同酶解方式制得的底物对美拉德反应产物的各检测指标(肽、氨基酸、糖等反应底物含量和美拉德产物含量及其抗氧化性能力)影响,并分析各检测指标间的相关性。实验表明:酶解程度对美拉德反应产物特性有显着性影响,酶解作用所得的肽具有更强的美拉德反应活性,酶解程度越大的酶解液,消耗糖量越多,生成的MRPs越多,其MRPs抗氧化活性越强,同一反应起始浓度,8 h与2 h酶解液的MRPs抗氧化能力相比,FRAP还原能力与DPPH·清除能力增强倍数高达2倍和7倍;美拉德反应能明显改善了酶解液的性质,可溶解性肽的含量最高增加了2倍,可溶性氨基酸最高增加了1倍,抗氧化能力最高增强了40倍;从检测指标的相关性可知,糖的消耗量变化一定程度上能反应美拉德反应的程度,美拉德反应能促进肽的分解生成氨基酸。     

Characteristics and antioxidant activity of ultrafiltrated Maillard reaction products from a casein–glucose model system

Maillard reaction products (MRPs) were prepared from casein–glucose by refluxing for 130 min at 102 °C and initial pH 12.0 without pH control to investigate the characteristics of casein–glucose Maillard reaction and the antioxidant activity difference among different fractions of MRPs. Browning and intermediate products increased, however, the pH of the system decreased with increase in the heating time. Free amino group content decreased 78% during first 10 min and did not change nearly thereafter. Amino acid analysis indicated that lysine and arginine decreased significantly, and casein was partially hydrolysed to peptides or free amino acid. High molecular weight compounds were dominant in the MRPs, determined by high performance gel-filtration chromatography. After ultrafiltration, antioxidant activity of each MRPs fraction was investigated by DPPH radical-scavenging activity, reducing power, Fe²⁺ chelating activity and lecithin oxidation assay. MRPs of different molecular weight exhibited distinctly different antioxidant activities.     

外源氨基酸对牡蛎肽美拉德反应产物风味特性的调控作用

为改善牡蛎肽美拉德反应产物腥味浓、鲜香味不足的问题,基于牡蛎肽-半胱氨酸-木糖体系,借助感官评定明确了外源氨基酸对其气味与滋味特性的影响,结合挥发性风味物质的组成、整体气味轮廓以及肽相对分子质量分布剖析了风味差异的原因。结果表明,与单一添加甘氨酸或谷氨酸相比,复合添加这两种氨基酸对牡蛎肽美拉德反应产物的去腥增香具有更理想的效果。甘氨酸和谷氨酸的协同作用显著降低了庚醛、辛醛等关键腥味化合物对整体气味属性的影响,挥发性风味成分的种类增加至21种,从而提高了整体香气的丰富性。与此同时,复合添加外源氨基酸促进了美拉德反应过程中牡蛎肽的降解,提高了相对分子质量小于1 000的呈味肽的比例,进而改善了体系的滋味品质。该研究可为调控牡蛎调味料风味品质提供科学依据。     

Sensory Characteristics and Antioxidant Activities of Maillard Reaction Products from Soy Protein Hydrolysates with Different Molecular Weight Distribution

Soy protein was hydrolyzed using two enzymes to obtain soy protein hydrolysate (SPH), the SPH was fractionated with ultrafiltration membranes to obtain peptide fractions below 1,000 Da (SP1) and 1,000–5,000 Da (SP2), and for the meantime, SPH was further completely hydrolyzed to get compound amino acids (CAA). Maillard reaction products (MRPs) were prepared from aqueous xylose–SPH/SP1/SP2/CAA model systems by heating at 120°C for 2.0 h. Compared with the original hydrolysates and other MRPs, the MRPs from SP2 exhibited a distinctly enhanced effect on flavor, including the caramel-like, soy sauce-like odors, umami and mouthful tastes and a greatly reduced bitterness in consomme′ soup. Antioxidant activities of SPH, SP1, SP2, CAA, and their MRPs were investigated through reducing power, DPPH radical-scavenging activity, and Fe²⁺ chelating activity. Before Maillard reaction, the antioxidant activities of peptide fractions with different molecular weights were quite different, and SP2 showed the highest activity; however, CAA exhibited very poor antioxidant activity. The antioxidant activities of SPH, SP1, SP2, and CAA were greatly enhanced by Maillard reaction, and the MRPs prepared from xylose–CAA model system exhibited a higher antioxidant activity than those from other model systems. Pyrazines, pyrroles, furans, and thiazoles were significantly correlated with reducing power and Fe²⁺ chelating activity by principal component analysis.     

不同氨基酸和糖对美拉德反应产物的影响

利用半胱氨酸、甘氨酸、谷氨酸3 种氨基酸和木糖、葡萄糖2 种还原糖作为反应底物,模拟美拉德反应制备香精,并对其香气成分和有害物质进行综合分析。结果表明：参与反应的氨基酸种类越多,所测得的挥发性物质种数也越多,反应产物的风味越丰富;甘氨酸参与的美拉德反应中丙烯酰胺的生成量较少,而谷氨酸的参与反应中丙烯酰胺的生成量较多;还原糖种类对丙烯酰胺的产生影响不大;谷氨酸参与的美拉德反应产物中,5-羟甲基糠醛（5-hydroxymethylfurfural,5-HMF）含量高,而半胱氨酸和甘氨酸参与的反应产物中,5-HMF的含量较低;木糖可减少产物中的5-HMF的含量。利用本实验条件制备香精,产物中的丙烯酰胺和5-HMF含量在安全范围内。     

鱿鱼内脏蛋白水解度对美拉德反应产物褐变程度的影响

以不同水解程度的鱿鱼内脏蛋白水解液为基料,通过美拉德反应制备鱿鱼味香精,研究反应前后氨基酸、多肽及还原糖含量的变化,探索蛋白水解程度对美拉德产物（MRPs）褐变程度的影响。结果表明：随着鱿鱼内脏蛋白水解度的增大,美拉德反应过程中氨基酸的消耗量增加,其中Arg、Glu、Lys、Leu的消耗量较大;多肽和还原糖的消耗量则先升高后降低,水解度为26.47%（水解4 h）时二者的消耗量达到最大;MRPs的吸光度及光谱扫描值也呈现先升高后降低的趋势,其色泽先加深再变浅。