scholarly journals Changes in Phytochemicals and Determination of Optimum Fermentation Time during Black Tea Manufacturing

2020 ◽  
Vol 12 (4) ◽  
pp. 657-664
Author(s):  
M. M. Rahman ◽  
M. M. Hossain ◽  
R. Das ◽  
I. Ahmad
Keyword(s):  
Black Tea ◽  
Quality Parameters ◽  
Biochemical Changes ◽  
Enzymatic Oxidation ◽  
Time Intervals ◽  
Fermentation Time ◽  
Tea Quality ◽  
Processing Steps

Black tea processing consists of four steps, namely withering, CTC, fermentation and drying, while cup quality made tea mostly controlled by fermentation step. This study evaluated biochemical changes at different stages of black tea processing in Bangladesh and determined the optimum fermentation time. Samples were collected from different tea processing stages to measure major phytochemicals and time intervals during fermentation to measure theaflavins and thearubigins ratio. Caffeine content was the least susceptible to processing steps. Biochemical changes started at withering, cell maceration and enzymatic oxidation started at CTC processing, thus the major reduction in the reducing sugar (20.46 to 04.95 ppm), catechin (16.88 to 7.95 ppm) and polyphenol (42.30 to 30.73 ppm) occurred here. The significant changes appeared during fermentation when polyphenol content decreased from 44.66 to 18.23 and catechin from 17.41 to 03.98 ppm due to the breakdown of these compounds to theaflavins (TF) and thearubigins (TR). The TF and TR ratio increased with fermentation time, and the highest of 1:8.4 was found at 50 min, which turned into 1:10 in the final product. The made tea quality parameters were comparable or better at fermentation time of 50 min than the quality of the black tea available in market.

Clonal Variations in the Response of Hard Physically Withered Leaf to Rehydration Following Long Chemical Wither Durations

2017 ◽  
Vol 13 (01-02) ◽  
Author(s):  
P. Okinda Owuor ◽  
Martin Obanda
Keyword(s):  
Black Tea ◽  
Quality Parameters ◽  
Tea Plant ◽  
Oxidative Enzymes ◽  
Quality Deterioration ◽  
Tea Quality ◽  
Genetic Makeup

Long chemical wither durations and hard physical wither reduce the quality of plain black tea, through reduction in total theaflavins production while encouraging thearubigins formation. Such quality reduction may vary with genetic makeup of the tea plant. However, rehydration reactivates activities of oxidative enzymes responsible for producing plain black tea quality parameters. Influence of rehydrating hard physically withered leaf that had undergone long chemical wither durations on two clonal plain black tea quality parameters were assessed. Rehydration restored the formation of plain tea quality parameters from hard physically withered leaf. However, quality deterioration due to long chemical wither duration could not be reversed by rehydration. The patterns of responses of the clones used were similar. Thus in the processing of plain black tea, efforts should be made to maintain chemical wither durations to below 30 hours. However, rehydration reverses reduced plain black tea quality parameters by hard physical withers to equivalent of chemical wither

scholarly journals Determination of the Chemical Composition of Tea by Chromatographic Methods: A Review

2015 ◽  
Vol 4 (3) ◽  
pp. 56 ◽  
Author(s):  
Alexandr Ya Yashin ◽  
Boris V. Nemzer ◽  
Emilie Combet ◽  
Yakov I. Yashin
Keyword(s):  
Chemical Composition ◽  
Volatile Compounds ◽  
Black Tea ◽  
Storage Conditions ◽  
Organoleptic Evaluation ◽  
Chromatographic Methods ◽  
Tea Quality ◽  
Processing And Storage ◽  
And Storage

<p>Despite the fact that mankind has been drinking tea for more than 5000 years, its chemical composition has been studied only in recent decades. These studies are primarily carried out using chromatographic methods. This review summarizes the latest information regarding the chemical composition of different tea grades by different chromatographic methods, which has not previously been reviewed in the same scope. Over the last 40 years, the qualitative and quantitative analyses of high volatile compounds were determined by GC and GC/MS. The main components responsible for aroma of green and black tea were revealed, and the low volatile compounds basically were determined by HPLC and LC/MS methods. Most studies focusing on the determination of catechins and caffeine in various teas (green, oolong, black and pu-erh) involved HPLC analysis.</p> <p>Knowledge of tea chemical composition helps in assessing its quality on the one hand, and helps to monitor and manage its growing, processing, and storage conditions on the other. In particular, this knowledge has enabled to establish the relationships between the chemical composition of tea and its properties by identifying the tea constituents which determine its aroma and taste. Therefore, assessment of tea quality does not only rely on subjective organoleptic evaluation, but also on objective physical and chemical methods, with extra determination of tea components most beneficial to human health. With this knowledge, the nutritional value of tea may be increased, and tea quality improved by providing via optimization of the growing, processing, and storage conditions.</p>

scholarly journals PENGARUH UMUR DAUN TEH DAN WAKTU OKSIDASI ENZIMATIS TERHADAP KANDUNGAN TOTAL FLAVONOID PADA TEH HITAM (Camellia sinesis)

2021 ◽  
Vol 10 (1) ◽  
pp. 41
Author(s):  
Jennifer Larisa Liem ◽  
Maria Marina Herawati
Keyword(s):  
Black Tea ◽  
Total Flavonoid ◽  
Enzymatic Oxidation ◽  
Average Level ◽  
Flavonoid Compound ◽  
Total Flavonoids ◽  
Tea Leaves ◽  
Time Treatment ◽  
Oxidation Stage

Flavonoid compound is an important compound of tea products. However, the flavonoid level content in black tea is lowest than other teas. This is due to the processing of black tea which has an enzymatic oxidation stage and  the tea age leaves when picking. Young tea leaves contain higher total flavonoids than old tea leaves. With an average level of total flavonoids, the young tea leaves is 27.76% qe w / w, while for the old tea leaves 18.61% qe w / w. However, the enzymatic oxidation time treatment did not affect the total flavonoids because the process only affected the quality of black tea steeping, on it’s colour, aroma, and taste. Keywords: age of tea leaves, black tea, enzymatic oxidation, total flavonoids

Changes in the quality parameters of clonal black tea due to fermentation time

1994 ◽  
Vol 64 (3) ◽  
pp. 319-326 ◽  
Author(s):  
Philip O Owuor ◽  
John E Orchard ◽  
Ian J McDowell
Keyword(s):  
Black Tea ◽  
Quality Parameters ◽  
Fermentation Time

scholarly journals Assessment of the Impact of Sewage Storage Ponds on the Water Environment in Surrounding Area

Proceedings ◽  
2020 ◽  
Vol 51 (1) ◽  
pp. 20
Author(s):  
Kairat Ospanov ◽  
Timur Rakhimov ◽  
Menlibai Myrzakhmetov ◽  
Dariusz Andraka
Keyword(s):  
Water Quality ◽  
Water Environment ◽  
Quality Parameters ◽  
Treated Wastewater ◽  
Groundwater Aquifer ◽  
Sewage Ponds ◽  
Basic Quality ◽  
The Impact

The paper presents the results of research on the environmental impact of sewage ponds serving the city of Kostanay (Kazakhstan). The scope of the research included the determination of basic quality parameters of raw and treated wastewater, an analysis of the chemical composition of groundwater in the vicinity of sewage ponds, and the analysis of the water quality of the Tobol River. The obtained results indicate that sewage from storage ponds, infiltrating into the ground, caused groundwater pollution in the area of about 100 km2 around the reservoirs. Due to the fact that the groundwater aquifer in the vicinity of sewage ponds feeds the Tobol River, it also affects water quality in the river, which does not meet the requirements for most of the analyzed parameters.

Clonal plain back tea quality parameters responses of hard physical withered leaf to rehydration and fermentation durations

2016 ◽  
Author(s):  
P. Okinda Owuor ◽  
And Martin Obanda
Keyword(s):  
Sensory Evaluation ◽  
Polyphenol Oxidase ◽  
Oxidase Activity ◽  
Black Tea ◽  
Quality Parameters ◽  
Moisture Loss ◽  
Polyphenol Oxidase Activity ◽  
Tea Quality

Hard physical withers in tea processing result in reduced plain black tea quality parameters, but improve flavoury black tea quality. Chemical withers with minimal moisture loss improve plain black tea quality parameters. But chemical withered leaf is normally bulky and not flaccid thus reducing maceration rates. Hard physical withers reduce polyphenol oxidase activity, thereby impairing ability of the leaf to produce high amounts of plain black tea quality parameters, especially theaflavins and thearubigins. This study examined if rehydrating hard physical withered leaf could improve its fermentability and influence fermentation duration, and if such changes are cultivar dependent. Rehydrating hard physical withered leaf increased (p≤0.05) total theaflavins, thearubigins, brightness, total colour and sensory evaluation of resultant black teas. The patterns of the responses did not vary with cultivars or fermentation duration. The theaflavins and brightness declined (p≤0.05) while thearubigins and total colour increased (p≤0.05) with long fermentation durations irrespective of withering regime. Results demonstrate that problems of plain black tea quality reduction due to hard physical withers can be partially reversed by rehydration to chemical wither standard, but the withering regime does not influence when maximum plain black tea quality parameters are produced.

The determination of optimum fermentation time in Turkish black tea manufacture

1997 ◽  
Vol 60 (1) ◽  
pp. 53-56 ◽  
Author(s):  
Mehmet Tüfekci ◽  
Saadettin Güner
Keyword(s):  
Black Tea ◽  
Fermentation Time

The changes in black tea quality due to variations of plucking standard and fermentation time

1998 ◽  
Vol 61 (4) ◽  
pp. 435-441 ◽  
Author(s):  
P Okinda Owuor ◽  
Martin Obanda
Keyword(s):  
Black Tea ◽  
Fermentation Time ◽  
Tea Quality

scholarly journals Assessing biochemical changes during standardization of fermentation time and temperature for manufacturing quality black tea

2013 ◽  
Vol 52 (4) ◽  
pp. 2387-2393 ◽  
Author(s):  
Tanmoy Samanta ◽  
Vijayakumar Cheeni ◽  
Shrilekha Das ◽  
Amrita Basu Roy ◽  
Bijoy Chandra Ghosh ◽  
...  
Keyword(s):  
Black Tea ◽  
Biochemical Changes ◽  
Fermentation Time ◽  
Manufacturing Quality

scholarly journals CALIBRATION OF A WEIGHING LYSIMETER FOR MEASURING COCOA EVAPOTRANSPIRATION

2020 ◽  
Vol 33 (3) ◽  
pp. 803-814
Author(s):  
GERLANGE SOARES DA SILVA ◽  
FRANCISCO ADRIANO DE CARVALHO PEREIRA ◽  
RODRIGO ALMEIDA SANTANA ◽  
THAÍS NASCIMENTO MENESES ◽  
OSWALDO PALMA LOPES SOBRINHO ◽  
...  
Keyword(s):  
Graduate Program ◽  
Direct Determination ◽  
Time Intervals ◽  
Regression Estimate ◽  
Agricultural Engineering ◽  
Load Cells ◽  
Individual Capacity ◽  
Weighing Lysimeter

ABSTRACT Well-operated and calibrated weighing lysimeters reliably determine the water demand of agricultural crops, and the quality of the data is evaluated through the error analyses attributed to the instrument. The objective of this study was to determine performance parameters of a weighing lysimeter and to evaluate its adequacy for the direct determination of cocoa crop evapotranspiration. The lysimeter with 1.44 m2 surface, supported on four load cells installed in the experimental area of the Graduate Program in Agricultural Engineering of the Universidade Federal do Recôncavo da Bahia, was calibrated at 3:00 a.m., using known masses at intervals of 02 minutes in five cycles of addition and removal. Data were collected using a datalogger coupled to four load cells with an individual capacity of 1000 kg, programmed to perform readings every 01 second, storing the averages of 15 minutes. The lysimeter showed excellent accuracy, with r2greater than 0.99 in the correlation between the standard masses and the signal of the load cells and standard error of linear regression estimate of 0.03 mm. The combination of repeatability and hysteresis errors with an uncertainty of 0.19% showed that the load cells have accuracy of ±0.07 mm, with resolution of 0.00033 mV, and sensitivity to detect mass changes below 0.1 mm, the system is adequate for direct measurement of cocoa ETc at time intervals of less than one hour.

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