cognitive-function

Author: Huiling Liang and Yuerong Liang and Junjie Dong and Jianliang Lu and Hairong Xu and Hui Wang

Hot water treatment was used to decaffeinate fresh tea leaf in the present study. Water temperature, extraction time and ratio of leaf to water had a statistically significant effect on the decaffeination. When fresh tea leaf was decaffeinated with a ratio of tea leaf to water of 1:20 (w/v) at 100 °C for 3 min, caffeine concentration was decreased from 23.7 to 4.0 mg g−1, while total tea catechins decreased from 134.5 to 127.6 mg g−1; 83% of caffeine was removed and 95% of total catechins was retained in the decaffeinated leaf. It is considered that the hot water treatment is a safe and inexpensive method for decaffeinating green tea. However, a large percentage of tea catechins was lost if rolled leaf and dry tea were decaffeinated by the hot water treatment and so the process is not suitable for processing black tea.

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Author: Hyong Seok Park and Hee Jin Lee and Min Hye Shin and Kwang-Won Lee and Hojoung Lee and Young-Suk Kim and Kwang Ok Kim and Kyoung Heon Kim

Due to the adverse effects of the caffeine in a variety of plant products, many methods have been explored for decaffeination, in efforts to remove or reduce the caffeine contained in plant materials. In this study, in order to remove caffeine from green tea (Camellia sinensis) leaves, we have employed supercritical carbon dioxide (SC–CO2), which is known to be an ideal solvent, coupled with a cosolvent, such as ethanol or water. By varying the extraction conditions, changes not only in the amount of caffeine, but also in the quantities of the principal bioactive components of green tea, including catechins, such as epigallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin gallate (ECG) and epicatechin (EC), were determined. The extraction conditions, including temperature, pressure and the cosolvent used, were determined to affect the efficacy of caffeine and catechin extraction. In particular, the type and concentration of a cosolvent used constituted critical factors for the caffeine removal, combined with minimal loss of catechins, especially EGCG. When the dry green tea leaves were extracted with SC–CO2 modified with 95% (v/v) ethanol at 7.0 g per 100 g of CO2 at 300 bar and 70 °C for 120 min, the caffeine content in the decaffeinated green tea leaves was reduced to 2.6% of the initial content. However, after the SC–CO2 extraction, a substantial loss of EGCG, as much as 37.8% of original content, proved unavoidable.

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Author: Shuhong Guo and Jingqi Yan and Tangbin Yang and Xianqiang Yang and Erwan Bezard and Baolu Zhao

Author: Tao Li and Long-jiang Yu and Mao-teng Li and Wei Li

Green teas (Camellia sinensis) from the non-Karst and the Karst areas of Yichang, Hubei Province, PR China, have been compared as regards l-proline content of the green tea and the quality, as well as the soil properties. The results showed that some qualities of green tea from the Karst region, such as a higher content of l-proline and a lower contents of aluminum and fluoride were beneficial. Other qualities of green tea from the Karst region, for example, the lower content of tea polyphenols, were not beneficial. The differences in amino acids and caffeine contents were not statistically significant.

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Author: Hyong Seok Park and Hyung-Kyoon Choi and Sung Jun Lee and Kwon Woo Park and Sung-Gil Choi and Kyoung Heon Kim

To remove caffeine from green tea, supercritical CO2 (SC-CO2) extraction using 95% (v/v) ethanol as a modifier was carried out on a laboratory scale in the ranges of 150–300 bar and 50–80 °C. The extraction yield of caffeine and catechins including epigallocatechin gallate (EGCG) increased with an increase in temperature at a constant pressure, and also increased with increasing pressure at a fixed temperature. When the CO2 mass flow rate increased, the total extraction yield of caffeine and catechins also increased, but the extraction efficiency of CO2, which was determined by the amount of the solutes extracted per amount of CO2 used, decreased, possibly due to the negligible effect of external mass transfer resistance around green tea particles and the reduced contact time for SC-CO2 and green tea. The reduction of green tea particle size by grinding also resulted in the enhanced extraction of caffeine and catechins, which indicates the larger particle size yielded the slower extraction rate. These results gave rise to the conclusion that internal mass transfer resistance is predominant over the external mass transfer resistance in the extraction of green tea by SC-CO2 like other herbaceous materials. In addition to the extraction of caffeine, the substantial amount of catechins was also found to be extracted during the decaffeination processes.

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Author: Hyong Seok Park and Nam Gyu Im and Kyoung Heon Kim

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Author:Christopher P. Chengelis and Jeannie B. Kirkpatrick and Karen S. Regan and Ann E. Radovsky and Melissa J. Beck and Osamu Morita and Yasushi Tamaki and Hiroyuki Suzuki

The beneficial health effects associated with drinking green tea are widely considered to be due primarily to tea catechins. Heat treatment of marketed green tea beverages for sterilization causes epimerization and/or polymerization of tea catechins. Safety studies on heat-treated tea catechins are limited. The objective of the present study was to evaluate potential adverse effects, if any, of two standardized green tea catechin (GTC) preparations: one that underwent heat sterilization (GTC-H) and one that was not heat-sterilized (GTC-UH). A decaffeinated preparation of the GTC-H (GTC-HDC) was also evaluated to ascertain if any effects were due to caffeine. The GTC preparations were administered to rats once daily at levels up to 2000 mg/kg/day for 28 days. There were no deaths attributable to the GTC preparations. The clinical condition of the animals, functional observational battery, motor activity, clinical pathology evaluations, organ weights, and gross necropsy findings were unaffected by any of the GTC preparations. GTC-HDC or GTC-UH dosing had no effects on body weights or microscopic findings, whereas lower body weights and food consumption were observed in the 1000 and 2000 mg/kg/day GTC-H group males. The no observed-adverse-effect level (NOAEL) for localized gastric effects for GTC-H was 1000 mg/kg/day. No other target organs were identified. Thus, the NOAEL for systemic toxicity following oral administration was 2000 mg/kg/day for GTC-H, GTC HDC, and GTC-UH under the conditions of this study.

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Identification of green tea’s (Camellia sinensis (L.)) quality level according to measurement of main catechins and caffeine contents by HPLC and support vector classification pattern recognition

Author: Quansheng Chen and Zhiming Guo and Jiewen Zhao

High performance liquid chromatography (HPLC) was identified green tea’s quality level by measurement of catechins and caffeine content. Four grades of roast green teas were attempted in this work. Five main catechins ((−)-epigallocatechin gallate (EGCG), (−)-epigallocatechin (EGC), (−)-epicatechin gallate (ECG), (−)-epicatechin (EC), and (+)-catechin (C)) and caffeine contents were measured simultaneously by HPLC. As a new chemical pattern recognition, support vector classification (SVC) was applied to develop identification model. Some parameters including regularization parameter (R) and kernel parameter (K) were optimized by the cross-validation. The optimal SVC model was achieved with R = 20 and K = 2. Identification rates were 95% in the training set and 90% in the prediction set, respectively. Finally, compared with other pattern recognition approaches, SVC algorithm shows its excellent performance in identification results. Overall results show that it is feasible to identify green tea’s quality level according to measurement of main catechins and caffeine contents by HPLC and SVC pattern recognition.

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Author: Wan-Joo Kim and Jae-Duck Kim and Jåaehoon Kim and Seong-Geun Oh and Youn-Woo Lee

Caffeine and EGCG (epigallocatechin gallate) were extracted from green tea using supercritical carbon dioxide (SCCO2) with water as a cosolvent. Experimental conditions were carefully chosen to selectively extract a large amount of caffeine from the green tea while to remain a large amount of EGCG in the green tea. Various experimental conditions were explored including temperatures ranging 40–80 °C, pressure ranging 200–400 bar, and water contents ranging 4–7 wt%. At 40 °C, 400 bar and the water content of 7 wt%, the caffeine extraction yield was 54% while the EGCG extraction yield was 21%, resulting in caffeine/EGCG extraction selectivity of 2.57. The larger caffeine extraction yield agreed well with estimation of solubility parameter differences between SCCO2/water and caffeine/EGCG. The extraction results using SCCO2/water were compared with conventional liquid solvent extraction using water or ethanol. The selectivity of caffeine/EGCG extraction with water was 0.88 and the selectivity of caffeine/EGCG extraction was 0.24 with ethanol. Thus SCCO2 extraction with water as a cosolvent is suitable for the selective extraction of caffeine from the green tea.

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Author: A.B. Sharangi

The medicinal effects of tea have a history dating back almost 5000 years. The chemical components of green tea chiefly include polyphenols, caffeine and amino acids. Tea also contains flavonoids, compounds reported to have anti-oxidant properties having many beneficial effects. Tea flavonoids reduce inflammation, have antimicrobial effects and prevent tooth decay. Consumption of tea may have diuretic effects due to the caffeine. A related compound found in tea is theophylline, a licensed medicine for the treatment of respiratory diseases such as asthma. Today’s computer-driven world can generate complicated lifestyle-related disorders and consumption of certain natural product like tea may very well replace the ill-effects of chemical drugs leading to a safer world with happier life. The paper is an overview of revealing all such ethno medicinal research efforts throughout the world over the times.

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