The chemistry of tea manufacture

Roberts, E. A. H.

doi:10.1002/jsfa.2740090701

Cited by 92 publications

(37 citation statements)

References 23 publications

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“…It is known that, with the increase in fermentation time, TF as well as the aroma of tea also changes [5].…”

Section: Detection Of Optimal Fermentation Time Using the Reference Mmentioning

confidence: 99%

“…The macerated tea leaf is placed on a metal tray or spread on the floor of the fermentation room and is given some time for fermentation. During the oxidation process of catechins, a series of chemical reactions lead to the formation of intermediate orthoquinones, which are further converted to a number of phenolic derivatives, including theaflavins (TF) and thearubigins (TR) [5]. The TF and TR act as pigmenting materials in finished tea.…”

Section: Introductionmentioning

confidence: 99%

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Monitoring the fermentation process of black tea using QCM sensor based electronic nose

Sharma

Ghosh

Tudu

et al. 2015

Sensors and Actuators B: Chemical

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“…It is known that, with the increase in fermentation time, TF as well as the aroma of tea also changes [5].…”

Section: Detection Of Optimal Fermentation Time Using the Reference Mmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Monitoring the fermentation process of black tea using QCM sensor based electronic nose

Sharma

Ghosh

Tudu

et al. 2015

Sensors and Actuators B: Chemical

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“…Simple sugars content increases and carbohydrate content gradually decreases (Roberts, 1962). Simple sugars formed from the breakdown of carbohydrates react with amino acids to produce the flavor in black tea (Dev Choudhury and Bajaj, 1980;Sanyal, 2011).…”

Section: Carbohydrates and Simple Sugarsmentioning

confidence: 99%

A Review of Withering in the Processing of Black Tea

Deb¹,

Pou²

2016

Journal of Biosystems Engineering

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Purpose: Tea is the most frequently consumed drink worldwide, next to water. About 75% of the total world tea production includes black tea, and withering is one of the major processing steps critical for the quality of black tea. There are two types of tea withering methods: physical and chemical withering. Withering can be achieved by using tat, tunnel, drum, and trough withering systems. Of these, the trough withering system is the most commonly used. This study focuses on the different types of withering, their effect on the various quality attributes of tea, and other aspects of withering methods that affect superior quality tea. Results: During physical withering, tea shoots loose moisture content that drops from approximately 70-80% to 60-70% (wet basis). This leads to increased sap concentration in tea leaf cells, and turgid leaves become flaccid. It also prevents tea shoots from damage during maceration or rolling. During chemical withering, complex chemical compounds break down into simpler ones volatile flavor compounds, amino acids, and simple sugars are formed. Withering increases enzymatic activities as well as the concentration of caffeine. Research indicates that about 15% of chlorophyll degradation occurs during withering. It is also reported that during withering lipids break down into simpler compounds and catechin levels decrease. Improper withering can cause adverse effects on subsequent manufacturing operations, such as maceration, rolling, fermentation, drying, and tea storage. Conclusion: Freshly harvested leaves are conditioned physically and chemically for subsequent processing. There is no specified withering duration, but 14-18 h is generally considered the optimum period. Proper and even withering of tea shoots greatly depends on the standards of plucking, handling, transportation, environmental conditions, time, and temperature. Thus, to ensure consumption of high quality tea, the withering step must be monitored carefully.

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“…Formation of orthoquinones, bisflavanols, theaflavins and thearubigins from the catechin precursors takes place during enzymic fermentation (Roberts, 1958a(Roberts, , 1958b. Caffeine plays a vital role in tea quality characteristics such as briskness and other taste properties (Dev Choudhury, Rahman, & Barbora, 1991;Hilton & Ellis, 1972;Roberts, 1962;Sanderson, 1972) and it is an important parameter for quality evaluation (Khokhar & Magnusdottir, 2002;Owuor, Horita, Tsushida, & Murai, 1986;Yao et al, 2006).…”

Section: Introductionmentioning

confidence: 98%