scholarly journals Authenticity evaluation of tea-based products

2008 ◽  
Vol 26 (No. 4) ◽  
pp. 259-267 ◽  
Author(s):  
H. Čížková ◽  
M. Voldřich ◽  
J. Mlejnecká ◽  
F. Kvasnička
Keyword(s):  
Experimental Data ◽  
Green Tea ◽  
Analytical Methods ◽  
Black Tea ◽  
Equivalent Amount ◽  
Chemical Markers ◽  
Tea Leaves ◽  
Total Polyphenols ◽  
The Mean ◽  
Tea Extract

This study proposes a method for estimating the content of tea in tea-based products. Broadly, this methodology is based on selecting chemical markers of the quality and authenticity of tea (and, therefore, of tea-based products), optimising the relevant analytical methods, and determining variations (type, origin, quality) among samples of green and black leaf teas. The contents of the selected markers (theobromine, caffeine, theanine, and total polyphenols) in tea-based products (iced teas, instant teas) were determined. Then, the dry tea content in these products, expressed as the equivalent amount of dry tea leaves, was calculated on the basis of two sets of mean data for these analytes: average literature data, and the mean experimental data obtained with our samples of leaf tea. With regards to the latter, we propose to use of the following averages for caffeine, theobromine, theanine, and polyphenols: for 100 g of black tea-based products 1.9 g, 0.13 g, 1.3 g, and 9.1 g, respectively; for 100 g of green tea-based products 1.9 g, 0.16, 1.7 g, and 14.7 g, respectively. Using this method, we found that approximately one third of the analysed samples failed to meet the tea extract levels required by German and Austrian legislations, while about 10% did not comply with the less demanding Czech legislative requirements.

scholarly journals Green Tea Daily Consume Reduced Free Radicals on Moderate Smokers

2018 ◽  
Vol 2 (2) ◽  
pp. 39
Author(s):  
Rosyanne Kushargina ◽  
Rimbawan Rimbawan ◽  
Budi Setiawan
Keyword(s):  
Free Radicals ◽  
Experimental Design ◽  
Antioxidant Capacity ◽  
Green Tea ◽  
Black Tea ◽  
Intervention Period ◽  
Tea Leaves ◽  
Positive Effects ◽  
Tea Infusions ◽  
Total Antioxidant

<p><em>Smoking </em><em>can </em><em>enhance </em><em>free radicals on blood plasma. Many previous studies proved that tea is a source of antioxidants which might reduce free radicals. Green tea is known to have the higher antioxidant capacity compared to </em><em>black tea</em><em>.</em><em> This study aim</em><em>s </em><em>to analyze the effect </em><em>of green tea on reduction of free radicals on moderate smokers</em><em>, using a pre-post experimental design. </em><em>Green tea infusions were prepared with commercially available dried tea leaves (Green Tea Gamboeng Series) from the </em><em>Research</em><em> </em><em>Centers of Tea</em><em> </em><em>and</em><em> </em><em>Cinchona</em><em> Gambung, West Java. </em><em>Nine moderate smokers (11-21 cig/day) aged 30-45 years were instructed to drink 200 ml green tea three times a day for </em><em>four</em><em> weeks. Total Antioxidant Capacity (TAC) of blood serum was measured at baseline and after four weeks intervention period. The level of TAC significantly increased from 1.18 m mol/L to 1.34 m mol/L after </em><em>four</em><em> weeks intervention (P=0.000). These results prove that drinking 200 ml of green tea </em><em>three</em><em> times a day for </em><em>four</em><em> weeks has a significant benefit reduc</em><em>ing f</em><em>ree radicals of moderate smokers. Moderate smokers are advised to consume green tea continuously to sustain these positive effects.</em><em></em></p>

Comparison of Antimutagenic Effect of Various Tea Extracts (Green, Oolong, Pouchong, and Black Tea)

1994 ◽  
Vol 57 (1) ◽  
pp. 54-58 ◽  
Author(s):  
GOW-CHIN YEN ◽  
HUI-YIN CHEN
Keyword(s):  
Salmonella Typhimurium ◽  
Green Tea ◽  
Aflatoxin B1 ◽  
Black Tea ◽  
Inhibitory Effect ◽  
Manufacturing Processes ◽  
Antimutagenic Effect ◽  
Oolong Tea ◽  
Tea Extract

The antimutagenic effects of various tea extracts prepared from nonfermented tea (green tea), semifermented tea (oolong tea and pouchong tea), and fermented tea (black tea) were investigated by Salmonella/microsome assay. No mutagenicity or toxicity in Salmonella typhimurium TA98 and TA100 was observed with any tea extract. The tea extracts markedly inhibited the mutagenicity of 2-amino-3-methylimidazo(4,5-f)quinoline, 3-amino-1,4-dimethyl-5H-pyridol(4,3-b)indole,2-amino-6-methyldipyrido(l,2-a:3′,2′-d)imidazole, benzo[a]pyrene, and aflatoxin B1 toward S. typhimurium TA98 and TA100 in the presence of S9 mixture, especially those of oolong and pouchong teas inhibited over 90% mutagenicity of these five mutagens at the dosage of 1 mg per plate. Among four tea extracts, black tea exhibited the weakest inhibitory effect on mutagenicity of these five mutagens. The mutagenicity of 4-nitroquinoline-N-oxide, a direct mutagen, was not inhibited by black and oolong tea extracts to S. typhimurium TA98 in the absence of S9 mixture but was increased by the tea extracts at the dose of 1 mg per plate to S. typhimurium TA100. As the antimutagenic effect of semifermented tea was stronger than nonfermented and fermented teas, some antimutagenic substances might be formed during manufacturing processes of tea.

scholarly journals Influence of phenolic compounds on sensory parameters of tea infusions

2004 ◽  
Vol 22 (SI - Chem. Reactions in Foods V) ◽  
pp. S195-S198
Author(s):  
P. Košulič ◽  
J. Pokorný ◽  
Z. Panovská
Keyword(s):  
Phenolic Compounds ◽  
Green Tea ◽  
Black Tea ◽  
Total Polyphenols ◽  
Iso Standards ◽  
Tea Infusions ◽  
Sensory Parameters

A set of 9 black teas and 10 green teas were analyzed. Sensory parameters of tea infusions were correlated with the content of total polyphenols (determined after Folin and Ciocalteu) and sensory parameters (determined after ISO standards). Total polyphenols affect both the astringency and the bitterness of green tea and black tea infusions. The relations are mainly semilogarithmic, but very close to linear. Sucrose decreased the astringency by 30–40%, and the bitterness was suppressed still more.

Semi-synthesis and proteasome inhibition of D-ring deoxy analogs of (–)-epigallocatechin gallate (EGCG), the active ingredient of green tea extract

2008 ◽  
Vol 86 (6) ◽  
pp. 495-502 ◽  
Author(s):  
Congde Huo ◽  
Guoqing Shi ◽  
Wai Har Lam ◽  
Di Chen ◽  
Quizhi Cindy Cui ◽  
...  
Keyword(s):  
Natural Product ◽  
Green Tea ◽  
Epigallocatechin Gallate ◽  
Proteasome Inhibition ◽  
Synthetic Route ◽  
Tea Leaves ◽  
Green Tea Leaves ◽  
Inhibitory Activities ◽  
Cistus Salvifolius ◽  
Tea Extract

A semi-synthetic route to the D-ring analogs of (–)-epigallocatechin gallate (EGCG) from the relatively abundant (–)-epigallocatechin (EGC), isolated from green tea leaves, is described. A natural product (13), found in Cistus salvifolius, its acetate (14) and analog (17) were synthesized by this method. Their inhibitory activities against proteasomes were investigated.Key words: green tea, (–)-epigallocatechin gallate (EGCG), (–)-epigallocatechin (EGC), proteasome inhibition.

Effect of different doses of un-fractionated green and black tea extracts on thyroid physiology

2010 ◽  
Vol 30 (8) ◽  
pp. 884-896 ◽  
Author(s):  
Amar K Chandra ◽  
Neela De ◽  
Shyamosree Roy Choudhury
Keyword(s):  
Thyroid Gland ◽  
Green Tea ◽  
Harmful Effect ◽  
Black Tea ◽  
Green Tea Extract ◽  
Male Rats ◽  
Thyroid Peroxidase ◽  
Black Tea Extract ◽  
Green And Black Tea ◽  
Tea Extract

Tea is a rich source of polyphenolic flavonoids including catechins, which are thought to contribute to the health benefits of it. Flavonoids have been reported to have antithyroid and goitrogenic effect. The purpose of this study was to evaluate whether high doses of green and black tea have a harmful effect on thyroid physiology. Un-fractionated green and black tea extracts were administered orally to male rats for 30 days at doses of 1.25 g%, 2.5 g% and 5.0 g%. The results showed that green tea extract at 2.5 g% and 5.0 g% doses and black tea extract only at 5.0 g% dose have the potential to alter the thyroid gland physiology and architecture, that is, enlargement of thyroid gland as well as hypertrophy and/or hyperplasia of the thyroid follicles and inhibition of the activity of thyroid peroxidase and 5′-deiodinase I with elevated thyroidal Na+, K+-ATPase activity along with significant decrease in serum T3 and T4, and a parallel increase in serum thyroid stimulating hormone (TSH). This study concludes that goitrogenic/antithyroidal potential of un-fractionated green tea extract is much more than black tea extract because of the differences in catechin contents in the tea extracts.

scholarly journals The concentration and health risk of potentially toxic elements in black and green tea—both bagged and loose-leaf

2020 ◽  
Vol 12 (3) ◽  
pp. 140-150
Author(s):  
Ali Heshmati ◽  
Freshteh Mehri ◽  
Javad Karami-Momtaz ◽  
Amin Mousavi Khaneghah
Keyword(s):  
Health Risk ◽  
Green Tea ◽  
Toxic Elements ◽  
Graphite Furnace ◽  
Daily Intake ◽  
Black Tea ◽  
Potentially Toxic Elements ◽  
Target Hazard Quotient ◽  
The Mean ◽  
Mean Concentration

The concentration of potentially toxic elements (PTEs), including lead (Pb), cadmium (Cd), arsenic (As), zinc (Zn), and copper (Cu), among 160 samples of black and green tea—both bagged and loose-leaf—in Iran was determined using a graphite furnace atomic absorption spectrophotometer (GF-AAS). Besides, the transfer rate of PTEs from made tea into tea infusion was investigated, and the related health risk for consumers was assessed. According to the results, the content of the PTEs is dependent on the type of tea (black or green), the place of cultivation (Iran or India), and the supplied form (both bagged and loose-leaf). The concentration of Pb, Cd, and As in green tea was significantly lower than black tea (P-value < 0.05). On the other hand, the contents of Zn and Cu in green tea were higher than the corresponding values for black tea. The mean concentration of Pb, As, and Zn in bagged tea samples was significantly higher than those of loose-leaf tea, while the Cd and As levels in Iranian tea samples were significantly lower than the Indian samples. Generally speaking, the mean concentration of Pb, Cd, As, Zn, and Cu were 0.59 ± 0.12, 0.12 ± 0.06, 0.16 ± 0.12, 14.23 ± 4.90, and 11.10 ± 2.49 mg kg?1, respectively. The mean transfer rates of Pb, Cd, As, Zn, and Cu were 7.78, 6.29, 9.27, 12.91, and 13.08%, respectively. The estimated daily intake (EDI) and noncarcinogenic quotient (target hazard quotient [THQ]) due to the ingestion of PTEs besides the carcinogenic risk of As and Cd were considered as acceptable.

scholarly journals Evaluation of Antibacterial Activity of Aqueous Extracts of Pomegranate Peels, Green Tea Leaves and Bay Leaves against Vibrio cholera

2013 ◽  
Vol 37 (1) ◽  
pp. 90-95
Author(s):  
Zainab A. Al-Dhaher
Keyword(s):  
Antibacterial Activity ◽  
Green Tea ◽  
Inhibitory Effect ◽  
Aqueous Extracts ◽  
Tea Leaves ◽  
Vibrio Cholera ◽  
Diffusion Technique ◽  
Green Tea Leaves ◽  
Inhibition Zones ◽  
The Mean

The antibacterial activity of aqueous extracts of Pomegranate peels, Green tea leaves, Bay leaves were evaluated in this study. Agar diffusion technique was applied. The three extracts were found to have inhibitory effect against Vibrio cholera and the mean of the diameter of inhibition zones ranges from (11-23 mm) for pomegranate peels, (9-20 mm) for Green tea leaves and (718mm) for Bay leaves extracts and statistically analyzed. There were significant differences between pomegranate peels, tea leaves and bay leaves extracts at each concentration used in this study. The pomegranate peels were found to have greater effects against Vibrio cholera followed by tea leaves, Bay leaves. Minimum bactericidal concentration (MBC) was also determined and it was shown that 10mg/ml was the MBC for pomegranate peels, 10-15mg/ml the MBC for tea leaves and 20-25mg/ml the MBC for Bay leaves.

scholarly journals SYNTHESIS OF SILVER NANOPARTICLES FROM SILVER NITRATE SOLUTION USING GREEN TEA EXTRACT (CAMELIA SINENSIS) AS BIOREDUCTOR

2017 ◽  
Vol 6 (1) ◽  
pp. 32-38 ◽  
Author(s):  
Wara Dyah Pita Rengga ◽  
Arie Yufitasari ◽  
Wismoyo Adi
Keyword(s):  
Particle Size ◽  
Silver Nanoparticles ◽  
Green Tea ◽  
Nitrate Solution ◽  
Green Tea Extract ◽  
Average Particle ◽  
Face Centered Cubic ◽  
Tea Leaves ◽  
Green Tea Leaves ◽  
Tea Extract

The synthesis of silver nanoparticles with micro size is highly required in antibacterial fields. The biorefinery material is highly potential as a bioreductor which is applied in the synthesis of nanoparticles. The bioreductor is made from green tea leaves extraction using aquadest to extract its active substance, the catechin which is derived from polyphenol. The polyphenol can reduce the synthesis of silver nanoparticles naturally. The result of FTIR analysis from green tea leaves extract containing polyphenol shown in the uptake functional groups is -OH group located in 3425 cm-1, C=O group located in 1635 cm-1, C=C group located in 1527, and 1442 cm-1 , and C-O group located in 1234 cm-1. The precursors of AgNO3 was used as the main synthetic material. The synthetic condition was resulted from the reaction between the extraction of green tea extract and AgNO3 as the precursors in the variation of synthetizing time. The heating process during synthesizing is done in 50 ?C along with stirring to foster the creation of silver nanoparticles. The analysis result of XRD shows that silver nanoparticles has the diffraction peaks in the angle of 2 theta that are 44.08, 64.40, and 77.51. The types of silver nanoparticles is Ag0 nanoparticles with face-centered cubic crystal structure. Based on TEM analysis, the size and particle size distribution can be determined using image J. The distribution shows that the longer synthesizing time, the bigger nanoparticles produced. With synthesizing times at 24 hours, 6 hours, 3 hours, and 2 hours produce average particle size of 26.4 nm; 9.2 nm; 8.4 nm; and 7.4 nm respectively.

Black tea increases hypertonic stress resistance in C. elegans

2018 ◽  
Vol 9 (7) ◽  
pp. 3798-3806 ◽  
Author(s):  
Pei Yuan ◽  
Lian-yun Pan ◽  
Li-gui Xiong ◽  
Jie-wen Tong ◽  
Juan Li ◽  
...  
Keyword(s):  
Green Tea ◽  
Stress Resistance ◽  
Black Tea ◽  
Green Tea Extract ◽  
Hypertonic Stress ◽  
C Elegans ◽  
Black Tea Extract ◽  
Tea Extract

Black tea extract is more effective than green tea extract in protecting C. elegans against hypertonic stress, within the studied concentration range.

Sign in / Sign up

Export Citation Format

Share Document