Doc:Tea
From Metabolomics.JP
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| − | {{#graph:pie|size=250x180;margin=0,0,0,0;title=Tea Consumption;legend=;label=; | + | {{#graph:pie|size=250x180;margin=0,0,0,0;title=World Tea Consumption;legend=;label=; |
black=77; | black=77; | ||
green=21; | green=21; | ||
oolong=2}} | oolong=2}} | ||
| − | | Per capita mean consumption of tea in the world is 120 mL/day <ref name="McKay">McKay DL, Blumberg JB (2002) "The role of tea in human health: An update" J Am Coll Nutr 21:1-13</ref>, the second most consumed beverage in the world (next to water). <ref name="Wu">Wu CD, Wei GX (2002) "Tea as a functional food for oral health" Nutrition 18(5):443-444</ref> | + | | Per capita mean consumption of tea in the world is 120 mL/day <ref name="McKay">McKay DL, Blumberg JB (2002) "The role of tea in human health: An update" J Am Coll Nutr 21:1-13</ref>, the second most consumed beverage in the world (next to water). Black tea is principally consumed in Western countries, while green tea is popular in Asia <ref name="Wu">Wu CD, Wei GX (2002) "Tea as a functional food for oral health" Nutrition 18(5):443-444</ref>. |
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| − | == | + | ==Composition== |
{| | {| | ||
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| − | | The major phenolics in green tea include catechins (flavan 3-ols). They are (-)-epigallocatechin-3-gallate (EGCG; 59% of total catechins), (-)-epigallocatechin (EGC; 19%), (-)-epicatechin-3-gallate (ECG; 13.6%), and (-)-epicatechin (EC; 6.4%) <ref name="McKay"/>. Catechins are converted to theaflavins and thearubigins in black tea <ref>USDA Database for the Flavonoid Contents of Selected Foods, Beltsville 2003</ref>. A cup of tea may contain 90 mg of EGCG <ref name="Wu"/>, but in human, EGCG is less bioavailable (i.e. absorbed) than other green tea catechins. <br/> | + | | The major phenolics in green tea include catechins (flavan 3-ols). They are (-)-epigallocatechin-3-gallate (EGCG; 59% of total catechins), (-)-epigallocatechin (EGC; 19%), (-)-epicatechin-3-gallate (ECG; 13.6%), and (-)-epicatechin (EC; 6.4%) <ref name="McKay"/>. Catechins are converted to theaflavins and thearubigins in black tea <ref>USDA Database for the Flavonoid Contents of Selected Foods, Beltsville 2003</ref>. A cup of tea may contain 90 mg of EGCG <ref name="Wu"/>, but in human, EGCG is less bioavailable (i.e. absorbed) than other green tea catechins. The bioavailability is different between species and genotypes <ref>Kim S, Lee MJ, Hong J (2000) "Plasma and tissue levels of tea catechins in rats and mice during chronic consumption of green tea polyphenols" Nutr Cancer 37:41-48</ref><ref>Loktionov A, Bingham S et al. (1998) "Apolipoprotein E genotype modulates the effect of black tea drinking on blood lipids and blood coagulation factors: A pilot study" Br J Nutr 79:133-139</ref>.<br/> |
After drinking tea, the plasma level of catechins reach their peaks (between 1-10 µmol/L) in 2 - 4 h <ref>Yang CS, Chen L et al. (1998) "Blood and urine levels of tea catechins after ingestion of different amounts of green tea by human volunteers" Cancer Epidemiol Biomarkers Prev 7:351-354</ref>. After 24 h, plasma levels of EGCG and EGC return to baseline, but that of ECG remains elevated in methylated forms<ref>Higdon JV, Frei B (2003) "Tea catechins and polyphenols: health effects, metabolism, and antioxidant functions" Crit Rev Food Sci Nutr 43:89-143</ref>. | After drinking tea, the plasma level of catechins reach their peaks (between 1-10 µmol/L) in 2 - 4 h <ref>Yang CS, Chen L et al. (1998) "Blood and urine levels of tea catechins after ingestion of different amounts of green tea by human volunteers" Cancer Epidemiol Biomarkers Prev 7:351-354</ref>. After 24 h, plasma levels of EGCG and EGC return to baseline, but that of ECG remains elevated in methylated forms<ref>Higdon JV, Frei B (2003) "Tea catechins and polyphenols: health effects, metabolism, and antioxidant functions" Crit Rev Food Sci Nutr 43:89-143</ref>. | ||
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{| class = "wikitable" | {| class = "wikitable" | ||
| − | ! colspan="4" | Major Composition (%) | + | ! colspan="4" | Major Composition (%)<ref>Belitz DH, Grosch W (1997) "Quimica de los Alimentos" Zaragoza Acribia</ref> |
|- | |- | ||
| − | ! Compound || Green tea || Black tea || Infusion (3min) | + | ! Compound || Green tea || Black tea || Black tea<br/>Infusion (3min) |
|- | |- | ||
| Proteins || 15 || 15 || trace | | Proteins || 15 || 15 || trace | ||
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| Oxidized phenolics || 0 || 25 || 4.5 | | Oxidized phenolics || 0 || 25 || 4.5 | ||
|} | |} | ||
| + | | | ||
| + | {| class = "wikitable" | ||
| + | ! colspan="4" | Caffeine Content in Beverages | ||
| + | |- | ||
| + | ! Product || content <small>(mg /150mL)</small> || Product || content <small>(mg /150mL)</small> | ||
| + | |- | ||
| + | | espresso coffee || 108-180 || normal coffee || 80-115 | ||
| + | |- | ||
| + | | instant coffee || 65 || black tea (3min brew) || 40-70 | ||
| + | |- | ||
| + | | oolong tea || 18-33 || iced tea || 29 | ||
| + | |- | ||
| + | | green tea (3min brew) || 15-25 || cola soft drink || 15-19 | ||
| + | |- | ||
| + | | hot chocolate || 4 || cocoa milk shake || 3 | ||
| + | |- | ||
| + | | decaffeinated coffee || 1-3|| decaffeinated tea || 0.6-3 | ||
| + | |- | ||
| + | | plain chocolate || 15 mg/20g || milk chocolate || 5 mg/20g | ||
|} | |} | ||
| + | |} | ||
| + | |||
| + | ==Human Health== | ||
| + | |||
| + | |||
| + | |||
| + | == | ||
| + | <references/> | ||
Revision as of 14:36, 22 December 2009
Classification 分類
- green tea
- It is non-fermented, i.e., produced by drying an steaming the fresh leaves of Camellia sinensis var. sinensis to inactivate polyphenol oxidases.
- oolong tea
- It is produced by partial fermentation before drying.
- black tea
- It is fully fermented by oxidation.
- red (pu-erh) tea
- It is fully fermented by microorganisms including Aspergillus spp. and Penicillium spp.
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|
Per capita mean consumption of tea in the world is 120 mL/day [1], the second most consumed beverage in the world (next to water). Black tea is principally consumed in Western countries, while green tea is popular in Asia [2]. |
Composition
| The major phenolics in green tea include catechins (flavan 3-ols). They are (-)-epigallocatechin-3-gallate (EGCG; 59% of total catechins), (-)-epigallocatechin (EGC; 19%), (-)-epicatechin-3-gallate (ECG; 13.6%), and (-)-epicatechin (EC; 6.4%) [1]. Catechins are converted to theaflavins and thearubigins in black tea [3]. A cup of tea may contain 90 mg of EGCG [2], but in human, EGCG is less bioavailable (i.e. absorbed) than other green tea catechins. The bioavailability is different between species and genotypes [4][5]. After drinking tea, the plasma level of catechins reach their peaks (between 1-10 µmol/L) in 2 - 4 h [6]. After 24 h, plasma levels of EGCG and EGC return to baseline, but that of ECG remains elevated in methylated forms[7]. |
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Human Health
==
- ↑ 1.0 1.1 McKay DL, Blumberg JB (2002) "The role of tea in human health: An update" J Am Coll Nutr 21:1-13
- ↑ 2.0 2.1 Wu CD, Wei GX (2002) "Tea as a functional food for oral health" Nutrition 18(5):443-444
- ↑ USDA Database for the Flavonoid Contents of Selected Foods, Beltsville 2003
- ↑ Kim S, Lee MJ, Hong J (2000) "Plasma and tissue levels of tea catechins in rats and mice during chronic consumption of green tea polyphenols" Nutr Cancer 37:41-48
- ↑ Loktionov A, Bingham S et al. (1998) "Apolipoprotein E genotype modulates the effect of black tea drinking on blood lipids and blood coagulation factors: A pilot study" Br J Nutr 79:133-139
- ↑ Yang CS, Chen L et al. (1998) "Blood and urine levels of tea catechins after ingestion of different amounts of green tea by human volunteers" Cancer Epidemiol Biomarkers Prev 7:351-354
- ↑ Higdon JV, Frei B (2003) "Tea catechins and polyphenols: health effects, metabolism, and antioxidant functions" Crit Rev Food Sci Nutr 43:89-143
- ↑ Belitz DH, Grosch W (1997) "Quimica de los Alimentos" Zaragoza Acribia
