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3. Biochemical transformations and nutrition
3.1 Composition
Freshly harvested tea leaves have a complex composition, with protein content ranging from 15 to 20% of dry weight, soluble carbohydrates from 5 to 7%, minerals and trace elements around 5% and amino acids from 1 to 4%. Once brewed, 1 L of tea contains : 1 g protein, 70 mg lipids (including 40 mg polyunsaturated fatty acids), 0 g carbohydrates, 4 g ash, minerals (potassium (255 mg), magnesium (20 mg), sodium, phosphorus, iodine, calcium (2 mg), manganese, zinc, copper, iron, selenium (0.5 μg) and B vitamins (B3/niacin, 1 mg, B2/riboflavin (0.15 mg), B5/pantothenic acid (0.11 mg), B9/folates (49.5 μg).
Based on polyphenol composition, there is a wide variety of teas, with a general shift from aglycone forms (epicatechin and catechin) in older...
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Biochemical transformations and nutrition
Quality control and social impact
Bibliography
- (1) - GRIGG (D.) - The worlds of tea and coffee: patterns of consumption. - GeoJournal, 57(4), p. 283-294 (2002) https://doi.org/10.1023/B:GEJO.0000007249.91153.c3
- (2) -...
Websites
Special volume of the journal Food Research International on tea: Tea – from bushes to mugs: composition, stability and health aspects edited by Anderson de Souza Sant'Ana. Volume 53, Issue 2, Pages 557-950 (October 2013) https://www.sciencedirect.com/journal/food-research-international/vol/53/issue/2
...Standards and norms
Methods for controlling tea quality have been developed and many are standardized in ISO standards. Thirty standards have been published and grouped together in ISO/TC 34/SC 8, the most important of which are :
- Black tea – Definition and basic requirements - ISO 3720 - 2011
- Green tea – Definition and basic requirements - ISO 11287 - 2011
- White tea – Definition - ISO/TR 12591 - 2013 ...
Regulations
For toxicology, Regulation (EC) no. 396/2005 applies, concerning maximum residue levels of pesticides in or on food and feed of plant and animal origin. For mycotoxins, there is no regulation concerning plain tea, but for the categories of flavored tea and tea or flavored tea containing other food ingredients, regulation (EC) no. 1881/2006 setting maximum levels for certain contaminants in foodstuffs applies.
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