Trace metals and flavonoids in different types of tea

The mineral and flavonoid contents of commercially available different types of teas (premium black, flavored black, green, and fruit tea) and the infusions produced from them were determined. Studied teas differed in the contents of elements between their raw materials and infusions. Iron and copper exhibited the lowest efficiency of extraction by hot water. For the most popular black tea brand (LiptonA (R) Yellow label) the efficiency of metal extraction decreased in the order: Co > Mn > Ni > Zn > Cu > Fe. Flavored black Citrus tea infusion had the highest content of Co and Ni, while Yellow label and Green Indonesia are a good source of Fe, Mn, and Zn. Flavonoids were predominantly present as glycosides. Rutin was present at much higher levels in black and green teas. Significant amounts of naringin and hesperidin were determined in tea infusions with citrus aromas or fruits.