Research Database

Author: Sancho Bañón and Pedro Díaz and Mariano Rodríguez and María Dolores Garrido and Alejandra Price

Green tea (GTE) and grape seed (GSE) extracts are proposed as preservatives for increasing the shelf life of low sulphite raw beef patties. The antioxidant and antimicrobial activities of both extracts were compared with ascorbate. Five groups were established for the patties: Control (with no additives), S (100 SO2), SA (100 SO2 + 400 sodium ascorbate), ST (100 SO2 + 300 GTE) and SG (100 SO2 + 300 GSE) (mg per kg of meat). Patties were stored at 4 °C in aerobic packaging for 0, 3, 6 or 9 days under retail display conditions. Meat spoilage (total viable and coliform counts, pH, lightness, chroma, hue angle, metmyoglobin and TBARS) was determined. The sensory contribution of the extracts to cooked patties was evaluated (colour, odour, flavour and texture). The results pointed to the possibility of using low SO2-vegetable extract combinations to preserve raw meat products. ST, SG and SA delayed microbial spoilage, redness loss and lipid oxidation, thus increasing the shelf life of the raw sulphite beef patties by 3 days. ST, SG and SA also delayed the onset of rancid flavours in cooked patties. No anomalous sensory traits were caused by either extract. Ascorbate, GTE and GSE improved the preservative effects of SO2 on beef patties, especially against meat oxidation. This suggested that the quantity of SO2 added can be reduced to obtain healthier raw meat products.

 

 

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Author: Christina A. Bursill and Mavis Abbey and Paul D. Roach

Green tea extracts enriched in catechins decrease plasma cholesterol in hamsters, mice and rats. The aims of this study were to determine whether a catechin-enriched extract of green tea could lower plasma cholesterol in the cholesterol-fed rabbit and to determine the mechanism of action. Four groups of six New Zealand White rabbits were initially made hypercholesterolaemic by feeding a 0.25% (w/w) cholesterol diet for 2 weeks before the diet was supplemented with a catechin extract from green tea at 0, 0.5, 1 or 2% (w/w) for 4 weeks. Administration of the crude catechin extract from green tea significantly (p < 0.05) lowered cholesterol in plasma (−60%), VLDL + IDL (−70%), LDL (−80%), liver (total by −25% and unesterified by −15%) and aorta (−25%) compared to control. There was a significant reduction in the cholesterol synthesis index (−60%) and a significant increase in hepatic LDL receptor activity (+80%) and protein (+70%) but there was no change in the intrinsic capacity to absorb cholesterol from the intestines. These results suggest that green tea catechins lowered plasma, liver and aortic cholesterol in the cholesterol-fed rabbit by lowering cholesterol synthesis and upregulating the hepatic LDL receptor.

 

 

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Author: Pon Velayutham Anandh Babu and Kuruvimalai Ekambaram Sabitha and Periasamy Srinivasan and Chennam Srinivasulu Shyamaladevi

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: Anna Rosa Sannella and Luigi Messori and Angela Casini and Franco Francesco Vincieri and Anna Rita Bilia and Giancarlo Majori and Carlo Severini

We show here that a crude extract of green tea as well as two of its main constituents, epigallocatechin-3-gallate (EGCG) and epicatechin gallate (ECG), strongly inhibit Plasmodium falciparum growth in vitro. Both these catechins are found to potentiate the antimalarial effects of artemisinin without interfering with the folate pathway. The importance of these findings and their mechanistic implications are discussed in view of future therapeutic strategies.

 

 

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Author: Reiko Ide and Yoshihisa Fujino and Yoshiharu Hoshiyama and Tetsuya Mizoue and Tatsuhiko Kubo and Truong-Minh Pham and Kiyoyumi Shirane and Noritaka Tokui and Kiyomi Sakata and Akiko Tamakoshi and Takesumi Yoshimura

Purpose To examine the relation of green tea consumption with oral carcinogenesis, we prospectively analyzed data from a nationwide large-scale cohort study in Japan. Methods A total of 20,550 men and 29,671 women aged 40–79 years, without any history of oral and pharyngeal cancer at baseline survey, were included in the present study. During a mean follow-up period of 10.3 years, 37 oral cancer cases were identified. The Cox proportional hazard model was used to estimate the hazard ratio (HR) and 95% confidence interval (95% CI) for oral cancer according to green tea consumption by sex, while adjusting for age, smoking, alcohol drinking, and other dietary factors. Results For women, the HRs of oral cancer for green tea consumption of 1–2, 3–4, and 5 or more cups per day were 0.51 (95% CI: 0.10–2.68), 0.60 (95% CI: 0.17–2.10), and 0.31 (95% CI: 0.09–1.07), respectively, compared with those who drank less than one cup per day (p for trend, 0.08). For men, no such trends were observed. Conclusions Our findings did not suggest a prominent inverse association of green tea consumption with oral cancer, although there was a tendency for a reduced risk in women.

 

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Author: Asuka Hino and Hisashi Adachi and Mika Enomoto and Kumiko Furuki and Yoshiyuki Shigetoh and Maki Ohtsuka and Shun-Ichi Kumagae and Yuji Hirai and Ali Jalaldin and Akira Satoh and Tsutomu Imaizumi

In Japan, metabolic syndrome used to be rare, and the level of coffee consumption was low. However, the Japanese life style has been changing rapidly, and these changes have been associated with a steady increase in the frequency of metabolic syndrome and with greater consumption of coffee. We examined the relationship between metabolic syndrome and the consumption of coffee or green tea. A total of 1902 Japanese aged over 40 years (785 men and 1117 women) received population-based health check-up in 1999. We measured components of metabolic syndrome (blood pressure, waist circumference, fasting plasma glucose, and lipid profiles). Eating and drinking patterns were evaluated by a food frequency questionnaire. Multivariate analyses were performed to clarify the association between coffee or green tea consumption and the components of metabolic syndrome. All components of metabolic syndrome except for HDL-cholesterol were significantly (p < 0.01) and inversely related to coffee but not green tea consumption by multivariate analysis after adjusting for confounding factors. The larger was the number of components of metabolic syndrome, the lower was the level of coffee consumption (p < 0.0001). In addition, there was a high frequency of metabolic syndrome in small coffee drinkers. Thus, coffee but not green tea consumption was inversely associated with metabolic syndrome.

 

 

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Author: Suchitra Katiyar and Craig A. Elmets and Santosh K. Katiyar

Human skin is constantly exposed to numerous noxious physical, chemical and environmental agents. Some of these agents directly or indirectly adversely affect the skin. Cutaneous overexposure to environmental solar ultraviolet (UV) radiation (290–400 nm) has a variety of adverse effects on human health, including the development of melanoma and nonmelanoma skin cancers. Therefore, there is a need to develop measures or strategies, and nutritional components are increasingly being explored for this purpose. The polyphenols present in green tea (Camellia sinensis) have been shown to have numerous health benefits, including protection from UV carcinogenesis. (−)-Epigallocatechin-3-gallate (EGCG) is the major and most photoprotective polyphenolic component of green tea. In this review article, we have discussed the most recent investigations and mechanistic studies that define and support the photoprotective efficacy of green tea polyphenols (GTPs) against UV carcinogenesis. The oral administration of GTPs in drinking water or the topical application of EGCG prevents UVB-induced skin tumor development in mice, and this prevention is mediated through: (a) the induction of immunoregulatory cytokine interleukin (IL) 12; (b) IL-12-dependent DNA repair following nucleotide excision repair mechanism; (c) the inhibition of UV-induced immunosuppression through IL-12-dependent DNA repair; (d) the inhibition of angiogenic factors; and (e) the stimulation of cytotoxic T cells in a tumor microenvironment. New mechanistic information strongly supports and explains the chemopreventive activity of GTPs against photocarcinogenesis.

 

 

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Author: Sara Anees Khan and Shubha Priyamvada and Natarajan A. Arivarasu and Sheeba Khan and Ahad Noor Khan Yusufi

Objective Green tea, consumed worldwide since ancient times, is considered beneficial to human health. We hypothesized that green tea would enhance antioxidant defenses and specific metabolic activities of rat intestine, liver, and kidney to improve their functions. Methods The effect of green tea given to rats in the diet or drinking water for 25 d was determined on blood chemistry and on activities of enzymes of carbohydrate metabolism, brush border membrane, and antioxidant defense. Results Serum glucose, cholesterol, phosphate, and body weight decreased, whereas the activities of lactate and malate dehydrogenases and glucose-6- and fructose 1,6-bis-phosphatases increased in the intestine and kidney but slightly changed in the liver. Activity of glucose-6-phosphate dehydrogenase profoundly increased in the renal cortex but decreased in other tissues. Lipid peroxidation increased in the intestine and renal medulla and decreased in the renal cortex and liver; catalase increased in all tissues but the medulla. Superoxide dismutase activity decreased in the intestine but increased in renal tissues. Activities of brush border membrane enzymes in general increased in the intestine and kidney. Conclusion Green tea consumption resulted in enhanced enzyme activities of carbohydrate metabolism and antioxidant defenses, which may lead to improved health.

 

 

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

 

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