Bitter and astringent substances in green tea: composition, human perception mechanisms, evaluation methods and factors influencing their formation

Deng, Shuaijun; Zhang, Ge; Aluko, Oluwaseun Olayemi; Mo, Zhijie; Mao, Jingjing; Zhang, Haibo; Liu, Xiaohui; Ma, Ming; Wang, Qian; Liu, Haobao

doi:10.1016/j.foodres.2022.111262

Cited by 54 publications

(23 citation statements)

References 99 publications

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“…In this study, we estimated the relative astringency of eight tea catechins via an in vitro assay by measuring the thickness of the emulsion layer comprising artificial oil bodies complexed with each catechin. The results showed that gallate-type catechins were more astringent than non-gallate-type catechins, with an astringency order of ECG > EGCG > GCG > CG > EGC > EC > GC > C ( Figure 1 ), which is in accordance with previous reported studies [ 10 , 14 , 41 ]. It seems that this in vitro assay for detecting relative astringency is practicable for assisting the sensory evaluation of tea infusions, although only one human salivary peptide (histatin 3) is employed to interact with catechins in the current assay system.…”

Section: Discussionsupporting

confidence: 92%

Exploring The Relative Astringency of Tea Catechins and Distinct Astringent Sensation of Catechins and Flavonol Glycosides via an In Vitro Assay Composed of Artificial Oil Bodies

Liu

Tzen

2022

Molecules

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Artificial oil bodies covered by a recombinant surface protein, caleosin fused with histatin 3 (a major human salivary peptide), were employed to explore the relative astringency of eight tea catechins. The results showed that gallate-type catechins were more astringent than non-gallate-type catechins, with an astringency order of epicatechin gallate > epigallocatechin gallate > gallocatechin gallate > catechin gallate > epigallocatechin > epicatechin > gallocatechin > catechin. As expected, the extension of brewing time led to an increase in catechin content in the tea infusion, thus elevating tea astringency. Detailed analysis showed that the enhanced proportion of gallate-type catechins was significantly higher than that of non-gallate-type catechins, indicating that tea astringency was elevated exponentially, rather than proportionally, when brewing time was extended. Rough surfaces were observed on artificial oil bodies when they were complexed with epigallocatechin gallate (a catechin), while a smooth surface was observed on those complexed with rutin (a flavonol glycoside) under an atomic force microscope and a scanning electron microscope. The results indicate that catechins and flavonol glycosides induce the sensation of rough (puckering) and smooth (velvety) astringency in tea, respectively.

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Section: Discussionsupporting

confidence: 92%

Exploring The Relative Astringency of Tea Catechins and Distinct Astringent Sensation of Catechins and Flavonol Glycosides via an In Vitro Assay Composed of Artificial Oil Bodies

Liu

Tzen

2022

Molecules

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“…All individual compounds of the catechin dimer had FC values above 1.9, except for theasinensin F ( Table 2 ).The significant increase in catechin dimers content in W5 may be due to the reduction of water caused by long-time withering, which allowed the conversion of low-molecular phenol oxidase to high-molecular phenol oxidase with higher catechol oxidase activity ( 36 , 37 ). Although the variability of the multiple catechin dimers was significant, the content of catechin dimers was low (The difference between the catechin dimers and catechin monomers was about 2 orders of magnitude in MS intensity).These substances have been proven to be taste-active compounds imparting bitterness and astringency to the tea infusion ( 38 ). On the basis of conventional bitter components such as CAF, EGCG without significant changes, we speculated that the significant increase in catechin dimer content may be one of the reasons contributing to the high scores of the electronic tongue bitterness sensor in samples W4 and W5.…”

Section: Resultsmentioning

confidence: 99%

Analyzing the influence of withering degree on the dynamic changes in non-volatile metabolites and sensory quality of Longjing green tea by non-targeted metabolomics

Shan

Chen

et al. 2023

Front. Nutr.

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Withering is an important processing stage in green tea, which contributes to the tea flavor quality. The aim of this work was to comprehensively investigate the changes of chemical features and flavor attributes in Longjing green teas produced with five different withering degrees (moisture content of 75.05, 72.53, 70.07, 68.00, and 64.78%, w.b.). Combined with human sensory evaluation, electronic tongue and chromatic differences analysis, an assessment of the relationship between the withering degree and the sensory quality of Longjing tea was obtained. By using a non-targeted metabolomics approach, 69 significantly differential metabolites were screened. As the withering degree increased, most free amino acids and catechin dimers were increased, largely attributed to the hydrolysis of proteins and catechin oxidative polymerization, respectively. The contents of organic acids as well as phenolic acids and derivatives were reduced. Interestingly, flavone C-glycosides decreased overall while flavonol O-glycosides increased. The correlation analysis revealed that metabolites such as theasinensin F, theasinensin B, theaflavin, theaflavin-3,3′-gallate, theaflavin-3′-gallate, malic acid, succinic acid, quinic acid, theanine glucoside and galloylglucose had a greater influence on the taste and color of tea infusion (|r| > 0.6, p < 0.05). Overall, an appropriate withering degree at a moisture content of around 70% is more favorable to enhance the Longjing tea quality. These results may enhance the understanding of green tea flavor chemistry associated with withering and provide a theoretical basis for green tea processing.

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“…For example, prodelphinidin B4 is a catechin polymer that usually presents a strong astringent taste ( Rinaldi, Jourdes, Teissedre, & Moio, 2014 ). Kaempferol 3-O-rutinoside, 7-O-rhamnoside, and patientoside A are glycosides that usually present a bitter taste and also show potential as bitterness markers in milk tea ( Deng et al, 2022 ). Surprisingly, l -aspartic acid, which contributes freshness in tea, showed a significant positive correlation with bitterness, astringency, and sourness in milk tea.…”

Section: Resultsmentioning

confidence: 99%

Effect of brewing conditions on the chemical and sensory profiles of milk tea

Yang

Cui²,

Zhu³

et al. 2022

Food Chemistry: X

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Bitter and astringent substances in green tea: composition, human perception mechanisms, evaluation methods and factors influencing their formation

Cited by 54 publications

References 99 publications

Exploring The Relative Astringency of Tea Catechins and Distinct Astringent Sensation of Catechins and Flavonol Glycosides via an In Vitro Assay Composed of Artificial Oil Bodies

Exploring The Relative Astringency of Tea Catechins and Distinct Astringent Sensation of Catechins and Flavonol Glycosides via an In Vitro Assay Composed of Artificial Oil Bodies

Analyzing the influence of withering degree on the dynamic changes in non-volatile metabolites and sensory quality of Longjing green tea by non-targeted metabolomics

Effect of brewing conditions on the chemical and sensory profiles of milk tea

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