Formation of black tea aroma

Sanderson, Gary W.; Grahamm, Harold N.

doi:10.1021/jf60188a007

Cited by 124 publications

(71 citation statements)

References 18 publications

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“…Uneven withering or less withering and excessive moisture content reduce the aeration and temperature control, which results in uneven fermentation (Sanderson and Graham, 1973;Tomlins and Mashingaidze, 1997). Over-withering also should be avoided, as it hinders the enzymatic activities that are responsible for color, brightness, aroma, and other quality attributes.…”

Section: Fermentation (Oxidation)mentioning

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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Section: Fermentation (Oxidation)mentioning

confidence: 99%

A Review of Withering in the Processing of Black Tea

Deb¹,

Pou²

2016

Journal of Biosystems Engineering

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“…The ratio of terpenoid species to nonterpenoid species has been used to classify black teas for their flavor quality. In particular, linalool and geraniol, which belong to the terpene alcohol family, always impart a sweet, flowery aroma on black tea (Sanderson et al, 1973;Vitzthum et al, 1975;Kawakami et al, 1995).…”

Section: Introductionmentioning

confidence: 99%

Aroma changes of black tea prepared from methyl jasmonate treated tea plants

Shi

Wang²,

et al. 2014

J. Zhejiang Univ. Sci. B

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Methyl jasmonate (MeJA) was widely applied in promoting food quality. Aroma is one of the key indicators in judging the quality of tea. This study examined the effect of exogenous MeJA treatment on tea aroma. The aroma components in black tea prepared from MeJA-treated fresh tea leaves were extracted using headspace solid-phase microextraction (HS-SPME) and were analyzed using gas chromatography-mass spectrometry (GC-MS) and GC-olfactometry (GC-O). Forty-five volatile compounds were identified. The results revealed that the MeJA-treated black tea had higher levels of terpene alcohols and hexenyl esters than the untreated tea. Moreover, several newly components, including copaene, cubenol, and indole, were induced by the MeJA treatment. The activities of polyphenol oxidase and β-glucosidase in fresh tea leaves changed after the MeJA treatment. Quantitative real-time polymerase chain reaction (qRT-PCR) analysis indicated that the gene expression levels of polyphenol oxidase and β-primeverosidase were upregulated by two and three folds, respectively, by the MeJA treatment (P<0.01); however, the gene expression of β-glucosidase was downregulated to a half level. In general, the aroma quality of the MeJAtreated black tea was clearly improved.

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