Monitoring of black tea fermentation process using electronic nose

Bhattacharyya, Nabarun; Seth, Sohan; Tudu, Bipan; Tamuly, Pradip; Jana, Arun; Ghosh, Devanita; Bandyopadhyay, Rajib; Bhuyan, Manabendra

doi:10.1016/j.jfoodeng.2006.09.006

Cited by 120 publications

(75 citation statements)

References 18 publications

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“…Moreover, the flavor of prepared tea could also be affected by insect infestation, stresses, and mechanical injury to tea plants (Bailey et al, 2005;Bhattacharyya et al, 2007;Cho et al, 2007). Methyl jasmonate (MeJA), a well-characterized fatty acid-derived cyclopentanone signal, can induce a series of changes in secondary metabolites in a wide range of plants (Alvarez et al, 2009;Kuźma et al, 2009;Qiu et al, 2009;Chen et al, 2011).…”

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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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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“…With oxidation, catechins start to form larger molecules through condensation, and non-volatile compounds such as TF and TR are formed. These produced compounds are responsible for the color and taste of black tea liquor Bhattacharyya et al, 2007). During the fermentation process, the green color of tea leaves changes to coppery brown.…”

Section: Sensory Characteristics Colormentioning

confidence: 99%

“…These volatile compounds include essential oils and amino acids. Amino acids combine with orthoquinone, which is an oxidized form of catechin, and play the most important role in determining the aroma of black tea (Co and Sanderson, 1970;Mahanta and Hazarika, 1985;Bhattacharyya et al, 2007). In the Indian tea industry, the fermentation process is judged using two defined smell peaks: the first nose and second nose.…”

Section: Aromamentioning

confidence: 99%

“…Such practices are subjective and prone to human error. There have been successful demonstrations of an electronic nose to overcome the problems of human error (Bhattacharyya et al, 2007). Tocklai (Tea Research Association, Assam, India) has identified major flavorand odor-determining chemical compounds present in black tea, as reported by Bhattacharyya et al (2007) and Sharma and Rao (2009); these compounds are listed in Table 3.…”

Section: Aromamentioning

confidence: 99%

See 1 more Smart Citation

Fermentation: The Key Step in the Processing of Black Tea

Pou¹

2016

Journal of Biosystems Engineering

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Background: The same plant, Camellia sinensis, is used to produce all types of tea, and the differences among the various types arise from the different processing steps that are used. Based on the degree of fermentation, tea can be classified as black, green, white, or oolong tea. Of these, black tea is the most or fully fermented tea. The oxidized polyphenolic compounds such as theaflavins (TF) and thearubigins (TR) formed during fermentation are responsible for the color, taste, flavor, and aroma of black tea. Results: Research indicates that an optimum ratio of TF and TR (1:10) is required to ensure a quality cup of tea. The concentrations of TF and TR as well as desirable quality characteristics increase as fermentation time increases, reaching optimum levels and then degrading if the fermentation time is prolonged. It is also necessary to control the environment for oxidation. There are no established environment conditions that must be maintained during the fermentation of the ruptured tea leaves. However, in most cases, the process is performed at a temperature of 24-29°C for 2-4 h or 55-110 min for orthodox tea or crush, tear, and curl (CTC) black tea, respectively, under a high relative humidity of 95-98% with an adequate amount of oxygen. Conclusion: The polyphenolic compounds in black tea such as TF and TR as well as un-oxidized catechins are responsible for the health benefits of tea consumption. Tea is rich in natural antioxidant activities and is reported to have great potential for the management of various types of cancers, oral health problems, heart disease and stroke, and diabetes and to have other health benefits such as the ability to detoxify, improve urine and blood flow, stimulate, and improve the immune system.

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“…Optimum fermentation is then extremely crucial in deciding the final quality of finished tea and it is very important to terminate the fermentation process at the right time. Bhattacharya et al [20,21] presented a study on real-time smell monitoring of black tea during the fermentation process using an e-nose (8 MOS sensors array) as well as prediction of the correct fermentation time. Different time-delay neural networks (TDNNs) and self-organizing map (SOM) methods for the prediction of optimum fermentation were used and both the methods appear to be suitable for the purpose.…”

Section: Using E-nosesmentioning

confidence: 99%