Spectrophotometric measurements of theaflavins and thearubigins in black tea liquors in assessments of quality in teas

Roberts, E. A. H.; Smith, R. F.

doi:10.1039/an9618600094

Cited by 125 publications

(55 citation statements)

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“…They constitute about 6 to 18% of dry weight [6]. In early 1960s, Woods and Roberts recognized the possible existence of relationship between black tea theaflavins and sensory evaluation [7]. Similar relationship is also reported in a few literatures [8,9,10,11].…”

Section: Introductionsupporting

confidence: 55%

“…Thus, the quality index assigned by the tea taster is subjective, and sometimes produces inconsistent results. Instrumental methods using spectrophotometry and High performance Liquid Chromatography (HPLC) are routinely used by the tea scientists to determine the above bio-chemical compounds [7,16,17,18,19] in tea for looking into the factors that affect tea quality. The instrumental analysis methods [20,21,22] are accurate, reliable and repeatable, and the repeatability and reproducibility of the analysis results are restricted only by the quality of the sample preparation.…”

Section: Introductionmentioning

confidence: 99%

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A Machine Vision System For Estimation Of Theaflavins And Thearubigins In Orthodox Black Tea

Akuli

Pal

Bej

et al. 2016

International Journal on Smart Sensing and Intelligent Systems

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-Orthodox black tea quality depends upon the amount of certain organic compounds present and out of these, theaflavins (TF) and thearubigins (TR) are the most important ones While TF is responsible for attractive golden colour, increased brightness and astringency in tea liquor, TR is reddish brown, reduces the brightness of tea liquor and contribute mostly for the ashy taste of the liquor with minor improvement in astringency. The rapid estimation of TF and TR thus may resolve the problem of certain uncertainty or ambiguity that may arise during quality assessment of tea by the tea tasters. In this paper, a new method for rapid measurement of concentration of TF and TR is described using a machine vision system taking images of tea liquor and employing artificial neural networks (ANN). The results show good correlation of estimated values of TF and TR with the actual concentrations obtained using ultraviolet-visible spectrophotometer (UV-VIS).

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Section: Introductionsupporting

confidence: 55%

Section: Introductionmentioning

confidence: 99%

A Machine Vision System For Estimation Of Theaflavins And Thearubigins In Orthodox Black Tea

Akuli

Pal

Bej

et al. 2016

International Journal on Smart Sensing and Intelligent Systems

View full text Add to dashboard Cite

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“…Analysis of Tf and Tr by spectrophotometry Tf and Tr analysis was carried out with the method described by Roberts and Smith (1961 Organic layer (10 ml) + 2.5% NaHCO 3 (10 ml)…”

Section: Methodsmentioning

confidence: 99%

“…Tf ratio was obtained from the ratio of optical densities at 380 and 460 nm and similarly for Tr ratio. The Tf ratio of optical densities at 380 and 460 nm should be 2.98 1 to indicate the complete removal of Tr during Tf extraction (Roberts and Smith 1961). The Tr ratio is generally found to be between 3.6 and 8.2.…”

Section: Organic Layer (4 Ml) + Methanol (21 Ml)mentioning

confidence: 99%

Comparative assessment of tea quality by various analytical and sensory methods with emphasis on tea polyphenols

et al. 2011

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Attempts were made to evolve an efficient technique for quality assessment of tea (Camellia sinensis) using a tyrosinase based biosensor to detect polyphenols (PP). Tyrosinase catalyzes the polymerization of PP to form theaflavins (Tf) and thearubigins (Tr) contributing to the colour and astringency of tea, which determine tea quality. Variation in biosensor response of tea infusions gave an indication of differential amount of Tf and Tr. A comparative study of quality attributes of 8 varieties of commercially available brands of tea (A-H) was done using biosensor and results were compared with conventional techniques such as spectrophotometry, high performance liquid chromatography (HPLC), Commission Internationale de I'Eclairage (CIE) system and sensory evaluation. Considerable correlation was observed among the biosensor, sensory and spectrophotometric evaluation of tea samples. Sample A showed high Tf content and also showed a relative high biosensor response whereas sample G showed relatively poor response. Application of biosensors would serve as a basis for the evaluation of market value of tea in the near future.

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“…3 -24 Attempts were made by researchers to explain the quality and various liquor characteristics of manufactured teas in terms of the chemical composition and biochemical behaviour of both the unprocessed tea shoots and the manufactured teas. Some earlier studies in this field are due to Roberts and Smith, 9 Wood and Roberts, 22 Deb and Ullah 6 and Biswas and Biswas, 3 among many others. Roberts and Smith 9 found that TFs and TRs were largely responsible for colour and strength and that TFs were factors in quality and briskness.…”

Section: Introductionmentioning

confidence: 98%

Predictability of price of tea from sensory assessments and biochemical information using data‐mining techniques

Paul

2008

J Sci Food Agric

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BACKGROUND: The valuation of tea depends on the sensory assessments made by the Brokers and Buyers (Tea Tasters) to a large extent, though the market conditions and the requirements of a particular Buyer play an important role in determining the basic prices of teas. Again, there are several biochemical quality parameters in tea on which the quality of a particular tea depends. It is not straightforward to establish the reflection of biochemical quality characteristics in tea on the Taster's sensory assessments and price because of the complex dynamics within chemical properties and the inherent subjectivity of quality evaluation through the Taster's scores. It is, however, important to judge the market valuation of teas from quality assessments and biochemical properties. This paper describes the advantages of using statistical data-mining techniques to explore the association of biochemical quality parameters in teas with the Taster's sensory assessments, and the application of a nonparametric statistical technique, multivariate adaptive regression splines (MARSplines), to establish the predictability of the realised prices of teas from sensory assessments.

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Spectrophotometric measurements of theaflavins and thearubigins in black tea liquors in assessments of quality in teas

Cited by 125 publications

References 0 publications

A Machine Vision System For Estimation Of Theaflavins And Thearubigins In Orthodox Black Tea

A Machine Vision System For Estimation Of Theaflavins And Thearubigins In Orthodox Black Tea

Comparative assessment of tea quality by various analytical and sensory methods with emphasis on tea polyphenols

Predictability of price of tea from sensory assessments and biochemical information using data‐mining techniques

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