Determination of flavonol glycosides in green tea, oolong tea and black tea by UHPLC compared to HPLC

2015 ◽  
Vol 183 ◽  
pp. 30-35 ◽  
Author(s):  
Heyuan Jiang ◽  
Ulrich H. Engelhardt ◽  
Claudia Thräne ◽  
Beate Maiwald ◽  
Janina Stark
Keyword(s):  
Green Tea ◽  
Black Tea ◽  
Flavonol Glycosides ◽  
Oolong Tea

Immobilization and Characterization of Tannase and its Haze-removing

2009 ◽  
Vol 15 (6) ◽  
pp. 545-552 ◽  
Author(s):  
Erzheng Su ◽  
Tao Xia ◽  
Liping Gao ◽  
Qianying Dai ◽  
Zhengzhu Zhang
Keyword(s):  
Kinetic Parameter ◽  
High Activity ◽  
Green Tea ◽  
Storage Stability ◽  
Residual Activity ◽  
Black Tea ◽  
Optimum Temperature ◽  
Oolong Tea ◽  
Optimum Ph

Tannase was effectively immobilized on alginate by the method of crosslinking-entrapment-crosslinking with a high activity recovery of 76.6%. The properties of immobilized tannase were investigated. Its optimum temperature was determined to be 35 ° C, decreasing 10 °C compared with that of free enzyme, whereas the optimum pH of 5.0 did not change. The thermal and pH stabilities of immobilized tannase increased to some degree. The kinetic parameter, Km, for immobilized tannase was estimated to be 11.6 × 10-4 mol/L. Fe2+ and Mn2+ could activate the activity of immobilized tannase. The immobilized tannase was also applied to treat the tea beverage to investigate its haze-removing effect. The content of non-estern catechins in green tea, black tea and oolong tea increased by 52.17%, 12.94% and 8.83%, respectively. The content of estern catechins in green tea, oolong tea and black tea decreased by 20.0%, 16.68% and 5.04%, respectively. The anti-sediment effect of green tea infusion treated with immobilized tannase was significantly increased. The storage stability and reusability of the immobilized tannase were improved greatly, with 72.5% activity retention after stored for 42 days and 86.9% residual activity after repeatedly used for 30 times.

scholarly journals Determination of Oxalate and Some Inorganic Anions in Green and Black Tea

2013 ◽  
Vol 67 (4-5) ◽  
pp. 429-432 ◽  
Author(s):  
Elena Yusenko ◽  
Evgeniya Polyntseva ◽  
Anna Lyzhova ◽  
Olga Kalyakina
Keyword(s):  
Oxalic Acid ◽  
Green Tea ◽  
Ion Chromatography ◽  
Black Tea ◽  
Inorganic Anions ◽  
Sample Treatment ◽  
Oxalate Concentration ◽  
Relative Standard ◽  
Oxalate Ions

Abstract Oxalate concentration differs in various daily consumed food products. The role of oxalic acid in the human body is very significant, as its compounds are responsible for the stability of biological membranes. However, insoluble calcium and magnesium oxalates can be accumulated in the body in the form of kidney stones. Oxalate concentration has been measured by high performance liquid, gas after derivatization and ion chromatography (IC). The most effective method for the simultaneous determination of oxalate and inorganic anions is ion chromatography with conductometric detection. Here, we report the results of the measurement of oxalic acid in bleak and green tea samples. Separation was performed by IC on an anion-exchange column Shodex IC SI-90 with surface-layer sorbent and conductimetric detection. The main analytical features of the method were: limit of detection of oxalic acid 0.03 mg/l, linear range 0.1-20 mg/l, correlation 0.9998, relative standard deviation 1%. The method did not need specific sample treatment and was successfully applied to the analysis of black and green tea samples. Oxalic acid was determined in the ranges 16.7-84 mg/l for green tea and 63-116 mg/l for black tea. Green tea contained lower oxalate ions concentration than black tea. The IC method has a lower detection limit for oxalate ions than HPLS and GC, ten and two times less, respectively

scholarly journals Comparative study of catechin levels from green tea, oolong tea and black tea product with various treatments

2021 ◽  
Vol 14 (1) ◽  
pp. 001-010
Author(s):  
Syamsu Nur ◽  
Andi Nur Aisyah ◽  
Alfat Fadri ◽  
Sharfianty ◽  
Amriani Sapra ◽  
...  
Keyword(s):  
Green Tea ◽  
Color Change ◽  
Black Tea ◽  
Processing Method ◽  
Uv Spectrophotometry ◽  
Uv Spectrum ◽  
Polyphenol Compounds ◽  
The Public ◽  
Chemical Reagents ◽  
Oolong Tea

Background: Tea is a refreshing drink that contains polyphenol compounds, namely catechins that are used for medicine and cosmetics. This study was to assess the content of catechin compounds in green tea, oolong and black tea products from Indonesia, China and Taiwan. Methods: Some tea products are brewed at varying temperatures (75±2; 85±2 and 95±20 C) and times (5; 10 and 15 minutes). Identification of catechin compounds was carried out using chemical reagents and UV spectrophotometry. The level of cathecin in tea products were analyzed by spectrophotometer at 280 nm wavelength. Results: The results obtained indicate that green tea, oolong tea and black tea contain epigallocatechin-3-gallate (EGCG) compounds according to the color change based on chemical reagents and for UV spectrum analysis which has λmax in the range 268-274 nm. The results of quantitative tests using UV-Vis spectrophotometry showed that the green tea samples gave the highest levels of catechins followed by oolong tea and black tea with brewing temperature at 95±20 °C. Conclusion: The catechin content of tea obtained from various products varies according to the type of processing method and the brewing temperature. Therefore, this study is expected to provide information related to catechin content to the public and researchers.

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.

The modulatory effect of infusions of green tea, oolong tea, and black tea on gut microbiota in high-fat-induced obese mice

2016 ◽  
Vol 7 (12) ◽  
pp. 4869-4879 ◽  
Author(s):  
Zhibin Liu ◽  
Zhichao Chen ◽  
Hongwen Guo ◽  
Dongping He ◽  
Huiru Zhao ◽  
...  
Keyword(s):  
Gut Microbiota ◽  
Green Tea ◽  
Black Tea ◽  
Tea Consumption ◽  
Obese Mice ◽  
High Fat ◽  
Oolong Tea

Tea consumption has been identified to have a gut microbiota modulatory effect, which may be related to its anti-obesity effect.

Determination of lemon and carbonate effects on caffeine content of various teas and investigation of daily caffeine intakes / Çeşitli çayların içerdikleri kafein miktarlarına limon ve karbonatın etkisi ve günlük alım miktarlarının incelenmesi

2016 ◽  
Vol 41 (5) ◽  
Author(s):  
Funda Demir ◽  
Azmi Seyhun Kıpçak ◽  
Özgül Dere Özdemir ◽  
Mehmet Burçin Pişkin ◽  
Emek Möröydor Derun
Keyword(s):  
Green Tea ◽  
Camellia Sinensis ◽  
Black Tea ◽  
Daily Maximum ◽  
Caffeine Content ◽  
Tea Infusions ◽  
Health Field

AbstractObjective: Tea (Camellia sinensis), has been used for health field in thousands of years. Caffeine is one of the key component in tea and investigation of caffeine is a popular working subject among the researches. The novelty of this study is not only the determination of the caffeine contents of the teas, but also how addition of lemon and carbonate effects the caffeine contents. Another aim of the study is the investigation of the daily caffeine intakes from teas.Methods: Tea infusions were prepared and caffeine contents were extracted by using chloroform and determined by UV-Vis Spectrophotometer. For lemon and carbonate addition experiments, lemon was added before the caffeine analysis and carbonate was added at the beginning.Results: Maximum caffeine contents from highest to lowest were seen in black, earl grey and green in classic teas; fennel, mint and sage in herbal teas; lemon, apple and rosehip in fruit teas. With lemon addition caffeine contents were increased except green tea and with carbonate addition caffeine contents were decreased except black and fennel tea. Daily caffeine intakes are found between 32.10% (green tea with carbonate) - 77.20% (black tea with lemon), 1.85% (sage tea with carbonate) - 4.05% (fennel tea with lemon) and 2.10% (rosehip with carbonate) - 4.00% (lemon tea with lemon) in classic, herbal and fruit teas, respectively.Conclusion: The significance of this study indicates that herbal and fruit teas contain caffeine, which is assumed zero in literature. The caffeine amount of herbal teas (20.79±0.36-30.68±0.63 ppm) were found barely higher than the fruit teas (22.87±0.54-28.54±0.75 ppm) but daily maximum caffeine intakes were found less than 5%. The daily maximum caffeine intakes were found in the teas as 525.36±2.84-20.79±0.36 ppm, where lemon addition increased to 617.90±3.54-22.97±0.58 ppm and carbonate addition decreased to 488.54±2.05-16.84±0.28 ppm.

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