Fermentation: The Key Step in the Processing of Black Tea

Pou, K.R. Jolvis

doi:10.5307/jbe.2016.41.2.085

Cited by 65 publications

(41 citation statements)

References 37 publications

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“…The infusion colour of oolong tea is generally reddish-brown in moderate to heavy fermented oolong and dark greenish colour in light fermented oolong 20 . Colour-determining compounds in light-fermented tea are composed of flavonols, flavones and oxidized polyphenolic compounds such as theaflavins (TFs) and thearubigins (TRs), while the major colour-determining compounds in moderate and heavy-fermented oolong tea are TRs and their oxidized polymers 21 . These could account for the discrepancy in infusion colour as brewing times increased, as observed in this study.…”

Section: Discussionmentioning

confidence: 99%

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Prediction of suitable brewing cuppages of Dahongpao tea based on chemical composition, liquor colour and sensory quality in different brewing

Zhang

Yang

Cheng

et al. 2020

Sci Rep

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oolong tea is famous for its characteristic of durably brewing. to explore suitable brewing cuppages and the scientific methods to brew Oolong tea in multiple steeping process. Dahongpao tea (Zhengyan, Banyan and Zhouyan tea) is well known Oolong tea variety, brewed at 14 times and assessed its chemical composition, infusion colour and sensory quality in different brewing intervals. The results showed that Zhengyan tea (A3) had the best quality of steeping among the chosen tea. It could be brewed up to 10 cuppages with 80% sensory score. The chemical composition and tea infusion colour strength were higher in Zhengyan tea. Though, 70% caffeine leached within first three steeping. The Forest regression model revealed that the suitable brewing time ranges between 4 and 10 in the chosen Dahongpao tea variety. This study provides a scientific method and suitable steeping times for the drinking of different Dahongpao tea through dynamic analysis of quantity of chemical composition, infusion colour strength and sensory quality. Oolong tea is well-known traditional Chinese tea. Dahongpao dated more than 350 years, is a representative of Oolong tea planted in Wuyishan, Fujian Province, China 1. Oolong tea attracts both domestic and foreign consumers due to its quality and characteristic of durably brewing. Generally, Dahongpao tea are classified as Zhengyan (A1, A2, A3) Banyan (B1, B2, B3) and Zhouyan tea (C1, C2, C3) based on different growing environments. Zhengyan tea grows in Wuyishan Scenic Area along the Jiuqu river at high altitude, with lots of gravel in soil, which create good ventilation and moderate acidity of soil for its growing, resulting in excellent quality. Banyan tea is planted around Zhengyan tea region, on red soil with high acidity; moreover, the soil is mostly clay. Therefore, the quality of Banyan tea is not that good as Zhengyan tea. Zhouyan tea is distributed on hilly area with alluvial soil full of calcium, causing its quality not that good as Zhengyan and Banyan tea. Besides, the quality of tea infusion depends on the types and tea/water ration of tea, temperature of water, brewing duration and times 2-4. To realize the best consumption quality experience of tea, scientific brewing methods are the key after cultivation and processing, especially for Chinese famous tea. Consumers are generally told that Oolong tea is suitable for continuous brewing up to more than 7 cuppages. This assertion is highly subjected to consumers' discretion and has not been validated by any scientific research. Sensory evaluation technique helps to determine the brewing cuppages and quality of tea infusion by its flavor strength. The flavor of tea infusion is determined by its chemical composition such as amino acids, caffeine, polyphenols and catechins. Several groups of compounds including phenolic compounds, purine alkaloids, amino acids, carbohydrates, nucleotides, organic acids and ions potentially contribute to the taste of tea. Sweetness of tea is mainly attributed to amino acids, as well as simple sugars such ...

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Section: Discussionmentioning

confidence: 99%

“…In this study, tea infusion colour changed from orange red or orange to light yellow. During the fermentation process, the green colouration of tea leaves changes to coppery brown 21 . According to the Dahongpao testing standard, Dahongpao tea infusion with orange or orange red colour is suitable for drinking.…”

Section: Discussionmentioning

confidence: 99%

Prediction of suitable brewing cuppages of Dahongpao tea based on chemical composition, liquor colour and sensory quality in different brewing

Zhang

Yang

Cheng

et al. 2020

Sci Rep

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“…[7] The chemical composition of tea varies with the different levels of fermentation. [18] The chemical components of tea include polyphenols, caffeine, inorganic elements, and amino acid. [8,19] Amongst these, polyphenols have been reported to be primarily responsible for health benefits of tea [20] and the primary components of polyphenols are catechins.…”

Section: Introductionmentioning

confidence: 99%

Physicochemical characteristics, sensory quality, and antioxidant properties of Paochung tea infusion brewed in cold water

Chiang

Tsou

Chang

et al. 2020

International Journal of Food Properties

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The health-maintaining effects of tea on the human body have been widely proven, even with the tea prepared by brewing tea leaves in cold water becoming a new choice other than hot water. In this research, quality and the antioxidant properties of the Pouchong tea infusions prepared with cold water and hot water were determined and explored their relationships under a consumer hedonic test. The results showed that the chemical components of cold tea infusions increased with increasing duration of brewing, and a maximal increment was observed during the first 2 h of brewing. All chemical components under investigation, except caffeine, were found to be higher in the cold tea infusions over 8 h as compared in the hot tea infusions. The antioxidant ability of cold tea infusion increased with increasing duration of brewing and approached the plateau after 12 hours. The chemical components showed a significantly positive correlation with the antioxidant activities (P < .01). Regarding the sensory analysis-consumer hedonic test, the cold tea infusions of 10, 12, and 14 h of brewing had the highest score in taste, the highest score in total acceptability, and the most popular in aroma, respectively.

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“…Tea fermentation includes enzymatic oxidation (oxidative fermentation process). When injury to the cell structure of the plant happens, the cell sap of the ruptured leaves allows response between the chemical constituents and the enzyme (PPO and PO) in the presence of atmospheric oxygen (Jolvis Pou, 2016). PPO and PO act on catechins in the presence of oxygen and oxidized polyphenolic compounds that are usually in dimer or polymer form.…”

Section: Introductionmentioning

confidence: 99%

“…PPO and PO act on catechins in the presence of oxygen and oxidized polyphenolic compounds that are usually in dimer or polymer form. These polyphenolic molecules (theaflavins and thearubigins) add to the bitter taste and dark colour of black tea (Almajano et al, 2008;Jolvis Pou, 2016).…”

Section: Introductionmentioning

confidence: 99%

The ramification of fermentation time on antioxidant properties of Napier grass herbal tea by black tea processing method

Ng¹,

Zin²,

Maidin³

et al. 2019

Food Res.

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Tea fermentation relates to the enzymatic oxidation of the leaves of the tea and the formation of dark pigments. This method is usually conducted in a setting where temperature and humidity can be regulated. However, the impact of fermentation time on the antioxidant characteristics of Napier grass herbal tea is still unanswered. This study aimed to determine the effect of fermentation time on antioxidant properties of Napier grass black tea. Napier grass was subjected to fermentation for 3, 6, 9, 12 and 24 hrs. Fresh and dried samples were extracted in water (95°C, 30 mins) and the extracts were then analysed by total phenolic content (TPC) assay, total flavonoid content (TFC) assay, diphenyl-picryl-hydrazyl (DPPH) assay, Ferric reducing antioxidant potential (FRAP) assay, ferric thiocyanate (FTC) method and thiobarbituric acid (TBA) method. Sample fermented for 9 hrs showed the highest results in TPC (18.32±0.38) and FRAP assay (91.00±2.78). Whereas, the highest flavonoids and antioxidant activity were found in dried sample without fermentation (control) in TFC (97.82±13.00) and DPPH (90.02±1.11). However, samples fermented for 3 to 9 hrs showed no significant difference with that of the fresh sample in TFC and DPPH indicating 3 to 9 hrs fermentation time did not affect the antioxidant properties of Napier grass. In FTC and TBA, all the fermented samples showed lower antioxidant activity than that of fresh samples and control. The results suggested that 9 h of fermentation time is suitable for the preparation of Napier grass black tea as it exhibited high antioxidant properties in TPC, TFC, DPPH and FRAP assays.

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Fermentation: The Key Step in the Processing of Black Tea

Cited by 65 publications

References 37 publications

Prediction of suitable brewing cuppages of Dahongpao tea based on chemical composition, liquor colour and sensory quality in different brewing

Prediction of suitable brewing cuppages of Dahongpao tea based on chemical composition, liquor colour and sensory quality in different brewing

Physicochemical characteristics, sensory quality, and antioxidant properties of Paochung tea infusion brewed in cold water

The ramification of fermentation time on antioxidant properties of Napier grass herbal tea by black tea processing method

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