酱油中鲜味二肽的分离鉴定及其呈味特性研究

为了明确酱油中鲜味肽的结构序列,本文对酱油中鲜味肽进行分离鉴定,并系统地研究了其呈味特性。酱油经超滤膜(膜通量:5 ku、3 ku和1 ku)分离获得4个组分(F1,F2,F3和F4),通过感官评定筛选出鲜味最强的组分F4(1 ku)。该组分通过Sephadex G-15凝胶层析色谱继续分离得到8个组分(P1、P2、P3、P4、P5、P6、P7和P8),经感官评定筛选出鲜味最强的组分P2。采用超高压液相色谱串联质谱技术对P2组分进行多肽结构鉴定,通过手动De novo测序得到4条新的鲜味肽,其序列分别是Asn-Pro(230.1135 u)、Ala-His(227.1026 u)、Gly-Pro(173.0929 u)和Gly-Leu(189.1230 u)。然后采用固相合成技术合成四条肽并通过感官评定和电子舌分析,结果表明四条肽均具有明显的鲜味或鲜味增强作用。进一步研究发现,酱油的鲜味不仅来自于谷氨酸和天冬氨酸等鲜味氨基酸,小分子肽类也是构成酱油鲜味的重要成分之一。     

氨基酸和肽在食品中的呈味作用

本文综述了在食品中有呈味作用的氨基酸和肽。天然氨基酸大多具有甜味或苦味,MSG有强烈的鲜味,阿斯巴甜、阿力甜、索马钳和莫奈林是强力甜味剂。鲜味二肽、咸味二肽、苦味肽、美味肽等也出现了潜在的商业价值。     

调味品减盐增鲜的研究进展

调味品是食品调味过程中的必需品,同时也是人体摄入盐分的主要来源。盐摄入过多会带来健康隐患,但减盐会降低食品的咸味和鲜味,从而降低食品品质。本文综述在减盐同时保证咸味、鲜味及其协调性的技术手段。减盐技术包含减少钠盐添加量、非钠盐替代物及增强咸味感知等方法,增鲜技术包含添加酵母抽提物、鲜味肽及鲜味氨基酸和肽的衍生物等方法。此外,乳酸菌、美拉德反应中间体、增味剂、呈味肽等的应用亦可达到减盐增鲜的双重效果。减盐增鲜技术的应用能够促进调味品行业的发展,但这些技术尚存在基础研究不足、实际应用较少、应用范围较窄、生产成本高等问题,解决这些问题是当前所面临的主要困难。本文详细阐述调味品减盐增鲜技术的基本原理、特点、目前研究存在的不足等,提出未来可能的发展方向,以期为调味品的减盐增鲜研究提供参考。     

葵花籽肽ALEPIER呈鲜机制及其鲜味稳定性

为评估葵花籽肽ALEPIER作为鲜味剂的实际应用价值,通过TS-5000Z智能味觉分析系统(电子舌)测定了葵花籽肽ALEPIER的呈鲜能力并利用分子对接技术探究其呈鲜机制,并与味精(谷氨酸钠,MSG)进行对比,探讨加工条件(pH、温度)和常见食品辅料(氯化钠、蔗糖、柠檬酸)对葵花籽肽ALEPIER鲜味的影响,考察其鲜味稳定性。另外,探讨了葵花籽肽ALEPIER对MSG鲜味的增强作用。结果表明：葵花籽肽ALEPIER的鲜味值和鲜回味值分别为4.09和1.02,均高于MSG的(3.27和0.84);分子对接结果显示葵花籽肽ALEPIER中的谷氨酸、精氨酸、亮氨酸和丙氨酸与鲜味受体T1R1/T1R3上的His71、Asp147、Ser148、Thr149、Ala170、Ser172、Tyr220、Ser276、Glu301和Ser385等氨基酸残基的结合是葵花籽肽呈鲜的关键机制;在pH 4.0～8.0范围内,葵花籽肽ALEPIER鲜味值随着pH的上升而显著上升;在20～121℃范围内,葵花籽肽ALEPIER的鲜味值不随温度的变化而改变;氯化钠可提升葵花籽肽ALEPIER的鲜味值;蔗糖对葵花籽...     

鲜味物质对鸡汤鲜味及风味的影响

通过向肉鸡鸡汤中添加不同鲜味物质,来考察对鸡汤鲜味的影响,研究发现:不同氨基酸对鸡汤的增鲜效果不同,MSG、L-Asp、L-Ser、Gly、L-Ala、L-Met等少数几种氨基酸具有增鲜效果,其中MSG对鸡汤香气提升明显;呈味核苷酸对鸡汤鲜味提升效果最好,IMP在增强鸡肉香味方面优于GMP;酶解提取物可以明显提高鸡汤的鲜味、醇厚感、回味、肉感和汤体滋味,其中香菇酶解提取物效果最好。优选MSG、IMP和香菇水解提取物3种鲜味物质,按照1∶1∶1进行复配使用,可以弥补单一鲜味物质的不足,使整体呈味效果更加均衡。项目研究对鲜味物质的复配和鸡汤产品的风味改善提供了一定的理论基础。     

基于GA-BP神经网络的鹰嘴豆美拉德肽的定向制备

基于BP神经网络技术结合遗传算法实现定向制备美拉德风味肽产品。以鹰嘴豆蛋白为原料,通过双酶(风味蛋白酶和碱性蛋白酶)逐级定向酶解技术制备不同水解度(DH%)鹰嘴豆蛋白酶解液,采用该酶解液进行美拉德反应后经描述性感官分析,将所得参数进行美拉德反应预测模型构建。结果:经BP神经网络和遗传算法优化,最优参数为水解度24%、反应初始温度85℃、反应时间31 min、反应初始pH 9.7、D(+)-木糖添加量1.2g,其感官评分近似为5.0,感官评价很高。经验证试验,该技术参数条件下制备的美拉德肽呈现明显的肉味、鲜味,并具有较长的持续感。该参数可以作为鹰嘴豆蛋白美拉德肽产品的最佳制备条件,相关研究成果可为高品质蛋白增鲜基料制备提供技术借鉴。     

牡蛎酶解液美拉德反应体系优化及产物营养评价

以牡蛎酶解液为氨基来源,与葡萄糖发生美拉德反应,以感官评分和褐变程度为指标,优化美拉德反应的工艺条件,并通过氨基酸评分、化学评分、必需氨基酸指数(essential animo acids index,EAAI)评价美拉德反应产物的营养品质。结果表明,葡萄糖美拉德反应的最佳工艺参数为葡萄糖添加量8%、反应温度110℃、pH 7.5、反应时间90 min;美拉德反应产物中18种氨基酸齐全,必需氨基酸含量占总氨基酸含量的32.99%,EAAI为71.568,营养品质较高。鲜味氨基酸含量丰富,Glu含量最高。     

虾头蛋白酶解对热反应型虾味香精风味特征的影响

利用风味蛋白酶、复合蛋白酶、碱性蛋白酶、木瓜蛋白酶和中性蛋白酶对中国对虾虾头蛋白进行水解,研究了水解过程中水解度和多肽含量的变化,并通过对虾头蛋白水解液美拉德反应产物(MRPs)的氨基酸组成、挥发性成分分析和感官评定,选出适合制备具有浓郁海鲜风味的虾味香精的蛋白酶。结果表明,5种蛋白酶在对虾头蛋白水解的过程中,水解度均逐渐增加,多肽含量先升高后降低;各水解液在美拉德反应后游离氨基酸含量普遍降低,5种MRPs主要呈鲜味、醇厚味和焦甜味,持续感较强。复合蛋白酶的蛋白水解液中多肽含量最高,其MPRs中鲜味氨基酸含量相对较高,肉香味、海鲜味和烤肉香味等特征风味较强,鲜味、持续感和醇厚味浓郁。     

鲜味肽与增鲜肽及其加工特性研究进展

鲜味肽与增鲜肽是食品中的关键滋味成分,具有风味突出等优势。同时,鲜味肽与增鲜肽种类复杂且常作为反应前体物影响食品的风味特性,对食品风味有重要影响。据统计分析,目前已报道鲜味肽与增鲜肽数量分别为208条和60条,鲜味肽氨基酸组成和空间结构是决定鲜味肽鲜味特性的重要因素,而增鲜肽具有更复杂的增鲜模式和构效关系。在食品加工过程中,鲜味肽与增鲜肽会作为活泼反应底物参与酶促与非酶促反应,并在一定条件下转变为鲜味更强或增鲜特性更优的反应产物,有利于食品风味品质的提升。作者系统分析了鲜味肽与增鲜肽的结构特性,探讨了基于不同加工方式其在食品加工过程中的变化及其对食品呈味特性的有益影响,并阐述了在研究过程中存在的问题和解决方案,旨在对鲜味科学研究及调味品行业的技术发展提供理论指导。     

带鱼多肽美拉德反应前后性质研究和结构表征分析

本研究以带鱼多肽为研究对象,通过美拉德反应对其改性,并对改性前后的性质进行研究和结构表征分析。结果显示,经过美拉德反应后,带鱼多肽的性质发生显著变化,其结构也发生明显改变。通过对比相关数据和分析,发现美拉德反应对带鱼多肽的改性具有重要影响,此结果为后续阶段的进一步研究和应用奠定了良好基础。     

Soy Sauce and Its Umami Taste: A Link from the Past to Current Situation

ABSTRACT: Soy sauce taste has become a focus of umami taste research. Umami taste is a 5th basic taste, which is associated to a palatable and pleasurable taste of food. Soy sauce has been used as an umami seasoning since the ancient time in Asia. The complex fermentation process occurred to soy beans, as the raw material in the soy sauce production, gives a distinct delicious taste. The recent investigation on Japanese and Indonesian soy sauces revealed that this taste is primarily due to umami components which have molecular weights lower than 500 Da. Free amino acids are the low molecular compounds that have an important role to the taste, in the presence of sodium salt. The intense umami taste found in the soy sauces may also be a result from the interaction between umami components and other tastants. Small peptides are also present, but have very low, almost undetected umami taste intensities investigated in their fractions.     

Umami Taste Enhancement of MSG/NaCl Mixtures by Subthreshold L-α-Aromatic Amino Acids

l ‐Phenylalanine (l ‐Phe) and l ‐tyrosine (l ‐Tyr) are L‐α‐aromatic amino acids that have recently been discovered to be important components of the savory fractions of soy sauce in addition to l ‐glutamate. Their effects are evaluated on the umami or savory taste of monosodium L‐glutamate (MSG), with or without sodium chloride (NaCl). Because l ‐Phe at subthreshold concentration (1.0 mM) significantly enhances an umami taste of a MSG/NaCl mixture (P= 0.000), combinations of 4 subthreshold concentrations (0, 0.5, 1.5, and 5.0 mM) of l ‐Phe with a weakly suprathreshold MSG (4.0 mM) and NaCl (80 mM) mixture were then rated for salty and umami intensities relative to those of standard solutions. L‐Phe was found to significantly enhance the umami tastes of the MSG/NaCl mixtures when it was added in a concentration range of 0.5 to 5.0 mM (P= 0.000). However, neither the umami taste of MSG alone nor the salty taste of NaCl alone was intensified. In a further experiment, l ‐Tyr at the 3 subthreshold concentrations (0, 0.5, and 1.5 mM) studied was shown to have the same activity as L‐Phe. The phenomenon of umami or savory enhancement by subthreshold aromatic amino acids in the soy sauce system has been established.     

甜油和酱油中氨基酸和还原糖含量的比较研究

探讨甜油和酱油中两种关键营养成分氨基酸和还原糖的含量差异,分析原料不同、工艺相近的两种调味品特征指标存在差异的原因,并提出甜油和酱油存在的优势和缺点。结果表明,甜油中氨基酸总量和鲜味氨基酸谷氨酸低于酱油,甜油和酱油中氨基酸总量分别为15.86～23.21 mmol/L和31.69～46.04 mmol/L,其中谷氨酸含量分别为2.94～7.54 mmol/L和20.62～35.34 mmol/L;但每类氨基酸含量差距不大,比较协调;甜油中甜味氨基酸比例较大,为49.41%,酱油中的鲜味氨基酸比例较大,为71.19%;甜油中还原糖含量（14.24～27.53 g/L）高于酱油（4.80～8.26 g/L）。因此,酱油因高氨基酸和谷氨酸含量鲜味明显、口感厚重,适合烧制菜肴,而甜油口感协调、丰满,适合炒菜和凉拌菜;另外,甜油中高含量的还原糖含量能够改善菜肴质量、色泽和口感。     

Evaluation of Peptide Contribution to the Intense Umami Taste of Japanese Soy Sauces

ABSTRACT: Koikuchi and tamari shoyu are 2 types of traditional Japanese soy sauce whose low-molecular-weight fractions (less than 500 Da) are known to have the most intense umami taste. Given that peptides were also abundant in some umami fractions of both shoyu, further investigation was conducted to evaluate the precise contribution of peptides to the soy sauce tastes. To locate and isolate peptide fractions, separation procedures using Sephadex G-25 SF, Sephadex G-10, and reversed-phase high-performance liquid chromatography (RP-HPLC) linked to sensory evaluation (by taste dilution analysis), as well as amino acid analysis were performed. Peptides having glutamyl residue were present in most peptide fractions. However, they all revealed negligible contributions to the intense umami taste of the soy sauces. On the other hand, free Glu, in the presence of sodium salt, as well as free Asp and several sweet-taste eliciting free amino acids were considered to be the main contributors to the umami taste of the soy sauces. This study of Japanese soy sauces gives a clear explanation of the frequently questioned peptide contribution to the taste of savory food product.     

pH值对酱油中呈味肽种类和呈味特性的影响

利用固相萃取技术结合超高效液相色谱-串联质谱法对不同pH值发酵酱油的酸性组分进行分离、鉴定和呈味特性分析。结果表明,从调控pH值发酵的酱油中鉴定出14 种呈味肽,从自然pH值发酵的酱油中鉴定出12 种呈味肽,其中8 种呈味肽在两种酱油中均鉴定出来。调控pH值发酵的酱油中含有较多良好呈味效果的小分子肽,其中ED、EE、EF、ESAY、AELY均在500 mg/L的质量浓度下呈鲜、酸味,口感丰富,鲜味阈值最低,FLET、SV在质量浓度500 mg/L条件下呈厚味;自然pH值发酵的酱油中SV、LLVVQ、ALVLL具有较突出的浓厚感,其中SV厚味阈值最低,为500 mg/L。定向合成QLLN、LLVVQ、ESAY、AELY、FLET、FLTW、ALVLL、QVELF、SV,并以0.03 g/100 mL将合成肽添加至市售酱油中,发现ESAY可显著降低酱油咸味,提高酱油厚味;QLLN增鲜效果显著;LLVVQ、AELY、FLET增鲜效果较为显著;SV的添加使酱油浓厚感突出,风味显著提高。结果表明,调控pH值发酵酱油含有的呈味肽具有良好的呈味效果,使酱油具有更突出的鲜味和厚味,丰富协调酱油的口感。     

Isolation and identification of two novel umami and umami-enhancing peptides from peanut hydrolysate by consecutive chromatography and MALDI-TOF/TOF MS

Peanut hydrolysate produced by crude protease extract from Aspergillus oryzae HN 3.042 was found to elicit intense umami and umami-enhancing effect. Taste profiles, amino acid and organic acid composition of peanut hydrolysate and its separation fractions by ultrafiltration were evaluated. The results revealed that peanut hydrolysate was mainly low molecular weight compounds. Fractions of 1-3 kDa and below 1 kDa prominently contributed to the umami taste and umami-enhancing effect of the peanut hydrolysate. The two fractions were further purified, using gel filtration chromatography and reverse-phase high-performance liquid chromatography (RP-HPLC), in combination with sensory evaluation, to obtain a umami peptide and umami-enhancing peptide. The active peptides were identified as Ser-Ser-Arg-Asn-Glu-Gln-Ser-Arg (SSRNEQSR, 963.9 Da) and Glu-Gly-Ser-Glu-Ala-Pro-Asp-Gly-Ser-Ser-Arg (EGSEAPDGSSR, 1091.1 Da), by MALDI-TOF/TOF MS, respectively.     

不同鲜味物质对干腌马鲛鱼鲜味的贡献与比较分析

以8?种市售干腌马鲛鱼为研究对象,通过比较不同产品中鲜味物质成分和含量差异,并结合其滋味强度值和味精当量的分析计算,以确定对干腌马鲛鱼鲜味贡献最大的物质。结果表明：干腌马鲛鱼具有突出的咸、鲜味和浓厚味感,而其鲜味主要是由谷氨酸、鲜味肽等鲜味物质和乳酸等增鲜物质赋予。在其鲜味物质中,谷氨酸的滋味强度值大于1（除3、5、7号样品）,显示出它对干腌马鲛鱼鲜味的突出贡献,超滤组分的感官分析和肽分子质量分布测定结果表明,分子质量小于1?000?Da的小分子肽对样品的鲜味具有重要贡献。此外,长时间的风干可能会促进乳酸和鲜味肽的生成,但随着水分的流失,其苦味和咸味也增高;而辅料蔗糖和白酒的添加将抑制乳酸的产生,且蔗糖能在一定程度上促进谷氨酸的生成。值得强调的是,8?种样品的核苷酸均已降解为肌苷（inosine,HxR）和次黄嘌呤（hypoxanthine,Hx）等苦味物质,且长时间的风干可能会促进HxR和Hx的积累。