Effects of steaming conditions on tea quality in the manufacturing of green tea (Sencha).

The objective of this work was to study the changes in chlorophyll contents in green teas stored under different conditions and to suggest the most suitable way and length of green tea storage. A secondary aim was to evaluate the possibility of using the chlorophyll content as an indicator of tea freshness. Samples for analysis were obtained from a range of tea-growing regions. Chlorophyll contents were measured using UV-vis spectrophotometry. Chlorophyll absorbance was measured at 642.5 and 660 nm. Prior to storage, chlorophyll concentration in teas ranged from 1.12 to 1.89 mg per 1 g of tea, which corresponded to data given by other authors. Storage was found to lead to a decline in chlorophyll concentration. From the 6th month of storage onwards, a significant decrease (P < 0.05) was observed in all samples, irrespective of storage conditions. Based on the findings of this study, original and metal packaging can be considered the most chlorophyll-friendly. On the other hand, glass and paper packaging stored in direct daylight were found to have the strongest impact on chlorophyll concentration. Overall, it can be concluded that the storage time can have a strong influence on oolong green tea colour as an important qualitative variable. Thus, the shelf-life of tea should be shorter than the 12 months claimed by most manufacturers. Once the relationship between changes in chlorophyll concentration and length of the storage period had been established, the chlorophyll content was suggested as an indicator of the storage time (freshness) of a tea substance.

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Effect of selenium spraying on green tea quality

Journal of the Science of Food and Agriculture ◽

10.1002/jsfa.952 ◽

2001 ◽

Vol 81 (14) ◽

pp. 1387-1390 ◽

Cited By ~ 17

Author(s):

Qiuhui Hu ◽

Jaun Xu ◽

Genxing Pan

Keyword(s):

Green Tea ◽

Tea Quality

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Green Tea Quality Evaluation Based on Its Catechins and Metals Composition in Combination with Chemometric Analysis

Molecules ◽

10.3390/molecules23071689 ◽

2018 ◽

Vol 23 (7) ◽

pp. 1689 ◽

Cited By ~ 26

Author(s):

Wojciech Koch ◽

Wirginia Kukula-Koch ◽

Łukasz Komsta ◽

Zbigniew Marzec ◽

Wojciech Szwerc ◽

...

Keyword(s):

Green Tea ◽

Quality Evaluation ◽

Chemometric Analysis ◽

Tea Quality

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Differential Contribution of Jasmine Floral Volatiles to the Aroma of Scented Green Tea

Journal of Food Quality ◽

10.1155/2017/5849501 ◽

2017 ◽

Vol 2017 ◽

pp. 1-10 ◽

Cited By ~ 5

Author(s):

Jian-Xia Shen ◽

Mohammad M. Rana ◽

Guo-Feng Liu ◽

Tie-Jun Ling ◽

Margaret Y. Gruber ◽

...

Keyword(s):

Heat Treatment ◽

Green Tea ◽

Manufacturing Processes ◽

Floral Volatiles ◽

Methyl Anthranilate ◽

Tea Quality ◽

Potent Odorants ◽

Floral Volatile ◽

Jasminum Sambac ◽

Differential Contribution

Tea volatiles’ generation and retention over manufacturing processes are crucial for tea quality. In this study, floral volatile adsorption and retention in green tea scented with Jasminum sambac flowers were examined over the scenting process. Out of 34 enhanced volatiles in the scented tea, β-ionone, β-linalool, indole, and methyl anthranilate were the most potent odorants with 5.1–45.2-fold higher odor activity values than the corresponding controls in the nonscented tea. Scenting efficiencies for the floral volatiles retained in the scented tea (the percentage of volatile abundance over its corresponding amount in jasmine flowers) ranged from 0.22% for α-farnesene to 75.5% for β-myrcene. Moreover, due to additional rounds of heat treatment for scented green tea manufacturing, some volatiles such as carotenoid-derived geraniol and β-ionone and lipid-derived (Z)-jasmone were heat-enhanced and others such as nonanal were heat-desorbed in the scented green tea. Our study revealed that dynamic volatile absorption and desorption collectively determined tea volatile retention and tea aroma. Our findings may have a great potential for practical improvement of tea aroma.

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Effects of late-autumn fertilizer dressing on accumulation of photosynthates in tea (Camellia sinensis) and its contribution to spring tea quality

The Journal of Agricultural Science ◽

10.1017/s0021859600075171 ◽

1990 ◽

Vol 115 (2) ◽

pp. 233-238

Author(s):

Y. Shen ◽

X. Yang ◽

X. Xie

Keyword(s):

Amino Acids ◽

Green Tea ◽

Camellia Sinensis ◽

Shoot Growth ◽

Early Spring ◽

Late Autumn ◽

Tea Quality ◽

Npk Fertilizer ◽

Leaves And Roots

SUMMARYTwo-year-old tea bushes were given NPK fertilizer on 12 November 1986 and 14CO2 on 22–23 December 1986 and 9–10 January 1987. Late-autumn fertilizer dressing stimulated photosynthate accumulation in the whole bush, especially in overwintering leaves and roots. Large amounts of photosynthates in overwintering leaves provide the nutrition required for early spring budding. Lateautumn dressing also accelerated the transport of photosynthates from leaves to roots in winter, where photosynthates, with absorbed nitrogen, synthesized more animo acids, especially theanine and phenylalanine. The re-use of photosynthates stored in the roots of the dressed bushes during shoot growth the following spring was also facilitated by late-autumn dressing. The contents of amino acids and caffeine in the shoots of dressed bushes were much higher than those in the control, whereas the content of polyphenol was lower than in the control. The results indicate that late-autumn dressing improves the quality of spring green tea.

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