云南大叶种茶中亲水性成分分析方法与鲜甜滋味特点研究

【作者】 王丹；

【导师】 任达兵； 汤建国；

【作者基本信息】 昆明理工大学 ， 轻工技术与工程（专业学位）， 2022， 硕士

【摘要】 茶是世界上最受喜爱的非酒精饮料之一。滋味是决定茶叶风味品质和市场价值的关键指标,而氨基酸、生物碱、核苷和核苷酸等亲水性物质是茶汤滋味的主要贡献者。云南省茶产品主要以大叶种茶的鲜叶为原料进行加工,然而目前对云南大叶种茶中亲水性成分的认识不够全面,缺乏能够同时准确定量多类亲水性成分的分析检测方法。因此,建立对多类亲水性成分的准确和灵敏的分析方法,有助于全面揭示不同种类云南大叶种茶叶亲水性成分的组成和差异。同时,基于亲水性成分的准确含量信息,建立茶汤滋味与亲水性成分的数学模型,对深入认识不同加工类型茶叶的滋味品质与物质基础质的联系具有重要意义。本论文的主要内容如下:1、高分辨质谱和三重四极杆串联质谱检测技术的茶叶亲水性成分定量性能比较。基于三重四极杆串联质谱和高分辨质谱的3种扫描模式,分别优化色谱和质谱条件后建立了3种定量分析方法。结果表明,通过优化流动相组成、碰撞电压、质谱离子源参数,可以显著提升分离效果和质谱响应(数十到数千倍)。根据数据处理复杂度、灵敏度、准确度、精密度和实际样本应用5个指标,多反应监测模式(Multiple Reaction Monitoring,MRM)具有更好的方法学性能(线性范围:0.005–201.341μg/m L;检测限:0.001–0.451μg/m L;定量限:0.004–0.893μg/m L)能够成功应用于茶汤样本,为进一步的茶叶样本分析奠定方法基础。2、不同类型云南大叶种茶叶中亲水性成分的定量分析。建立了亲水作用液相色谱-三重四极杆串联质谱分析方法,方法学验证结果表明其具有良好的线性范围(0.003–200.925μg/m L,R~2>0.99),较低的灵敏度(检测限和定量限分别为0.001–0.148μg/m L和0.002–0.493μg/m L),以及良好的精密度和准确度。应用所建立的方法,成功对云南大叶茶中45种亲水性成分进行准确定量分析。结果表明,鲜味氨基酸和鲜味增强剂核苷酸在绿茶和普洱生茶中的含量普遍较高。相比之下,在红茶和普洱茶中,少数氨基酸(如脯氨酸和γ-氨基丁酸)以及大多数生物碱和核苷的含量明显较高。通过正交偏最小二乘判别分析,本工作进一步建立了4种茶叶的分类模型。3、云南大叶种茶茶汤鲜、甜味的量化评价与预测模型研究。基于鲜、甜滋味的等效量化感官评价,结合茶汤中亲水性成分的定量结果,通过相关分析和回归分析筛选出与茶汤鲜味和甜味显著相关的亲水性成分,并建立了鲜、甜滋味强度的预测模型。结果表明,茶氨酸、谷氨酸、天冬氨酸、高丝氨酸、蛋氨酸、腺嘌呤核苷以及尿嘧啶核苷酸是影响茶汤鲜味和甜味的重要成分。本工作建立的模型能够较好地预测鲜味强度(R~2=0.89),但甜味的预测效果较差(R~2=0.54)。更多还原

【Abstract】 Tea is one of the most popular non-alcoholic drinks in the world.Taste is a crucial factor that determines the sensory qualities and commercial prices of tea.Hydrophilic compounds including amino acids,alkaloids,nucleosides and nucleotides play critical roles in the taste of tea.Tea products in Yunnan are made from the fresh leaves of large-leaf tea species.However,hydrophilic components in Yunnan large-leaf tea are still not known comprehensive enough,and there is a lack of analysis methods that can accurately quantify kinds of hydrophilic components at one time.Therefore,this work aimed to develop an accurate and sensitive analytical method for kinds of hydrophilic components,and comprehensively reveal the composition and differences of hydrophilic components in different kinds of Yunnan large-leaf tea.At the same time,establishing the mathematical model of tea taste and hydrophilic composition has great significance to deeply understand the relationship between taste quality and hydrophilic components of different types of tea.The main contents of this thesis are as follows:1.Comparison of the performance of quantification of tea hydrophilic components by high resolution mass spectrometry and triple quadrupole mass spectrometry.Based on the three scanning modes of the two kinds of mass spectrometry,three quantitative analysis methods were established respectively from the optimized conditions of chromatography and mass spectrometry.The results showed that,the composition of mobile phase,collision voltage and MS ion source parameters have significant effects on the quantitative performance of the three mass spectrometry modes(MS response intensity were improved by tens to hundreds of times).After the comparation of data processing complexity,sensitivity,accuracy,precision and application of samples.Multiple Reaction Monitoring(MRM)showed better methodological performance(linear range:0.005–201.341μg/ml;limit of detection:0.001–0.451μg/m L;limit of quantification:0.004–0.893μg/m L)and was successfully applied to tea samples,which laid a foundation for further analysis of tea samples.2.Quantitative analysis of hydrophilic components in different types of Yunnan large-leaf tea.Based on the hydrophilic interaction chromatography coupled with triple quadrupole-tandem mass spectrometry,this work developed and validated a method,which showed a good liner range(0.003–200.925μg/m L,R~2>0.99)and sensitive(limit of detection:0.001–0.148μg/m L;LOQ:0.002–0.493μg/m L)and good precision and accuracy.This method was successfully used to determine the contents of 45 hydrophilic constituents in Yunnan large-leaf tea.Umami amino acids and umamienhanced nucleotides generally exhibited higher content in green tea and Pu-erh raw tea.By contrast,a few number of amino acids(e.g.,proline andγ-aminobutyric acid)and most alkaloids and nucleosides showed significantly higher contents in black tea or Pu-erh ripen tea.By performing the orthogonal partial least squares discriminant analysis,classification models for distinguishing four types of tea were established.3.Study on quantitative evaluation and prediction model of Umami and sweet taste of Yunnan large-leaf tea soup.The correlation analysis and regression analysis were carried out based on the equivalent quantification of tea taste(umami and sweet)and the quantitative results of hydrophilic components.The significant correlation of hydrophilic compounds was screened out,and prediction model was established.The regression coefficient between the predicted scores and the observed score of the tea sample was 0.89 and 0.54 respectively.The results showed seven hydrophilic compounds(theanine,glutamic acid,aspartic acid,homoserine,methionine,Adenosine and Uridine 5′-monophosphate)have significant influence on umami and sweet taste.The model established could predict the intensity of umami taste(R~2=0.89)well,but the prediction of sweetness is poor(R~2=0.54).更多还原