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Studies on some trace elements in various grades of tea. Part I. Zinc, manganese, copper and iron content in dry tea and tea infusions



Studies on some trace elements in various grades of tea. Part I. Zinc, manganese, copper and iron content in dry tea and tea infusions



Bromatologia i Chemia Toksykologiczna 29(2): 157-165



Zinc, manganese, copper and iron content was determined in twenty grades of tea and tea infusions by atomic absorption spectroscopy using a Pye Unicam SP 192 apparatus. The following average concentrations were found in dry tea products: zinc - from 21.90 ppm to 57.80 ppm, degree of extraction (DE) from 27.3% to 56.0%; manganese - from 412.50 ppm to 11 23.75 ppm, DE 20.5% to 51.9%; copper - from 20.50 ppm to 46.40 ppm, DE 10.8% to 28.3%; iron - from 116.50 ppm to 744.00 ppm, DE 2.5% to 10.1%. Overnormative amounts of copper in all tested tea samples may point to extensive use of copper fungicides in tea plantations. No evident differences were observed in trace elements content (except for iron) between the leaf and granulated tea grades. The elements were not completely extracted to water phase during infusion, and the degree of extraction was not identical for all of them. Lowest extraction rate was observed for iron (about 10% maximum), followed by copper, manganese, and zinc (56% maximum).

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