PL
W wybranych gatunkach herbat rynkowych, herbatek owocowo-ziołowych i ziołowych, w suszu oraz w naparach, oznaczono zawartość azotanów i azotynów. Zastosowano metodą kolorymetryczną z odczynnikami Griessa.
EN
The content of nitrate and nitrite were determined in 13 sorts of tea, in 3 sorts of fruit tea, in 4 sorts of herbal fruit tea and in 6 sorts of herbal tea. The concentrations were measured in the infusions and dried materials.The Griess colorimetric method were used in this study. It was found that nitrate levels in the ranged from 48.5 mg% (Earl Grey) to 1280.5 mg% (Indian granulated tea). The good blanded teas contain lower quantity of nitrates, for instance Pickwick - 80 mg%, or Labot Silver - 55.6 mg%. Cheaper sorts of tea contain higher levels of nitrates: Madras - 538.9 mg%, Ceylon - 1087.6 mg%. In the fruit teas and herbal-fruit teas the lowest contents of nitrates were determined in Wieloowocowa - 3.3 mg%, Róża - 7.1 mg%, Cytrynka - 40.4 mg%, Wyborna - 188.6 mg% whereas very high contents was measured in Gdańska tea in which formula there is a nettle herb. High levels of nitrates in camomile herbal tea (4.3 - 269,5 mg%) and in mint herbal tea (107.8 - 700.8 mg%) show that both sorts ought to be used carefully in infants. The content of nitries in herbal tea were very low. In 9 sorts of black tea the content of this compond was 0 whereas in 4 sorts ranged from 0.13 mg% (Madras) - 3.1 mg% (Ceylon). On the basis of comparising the levels of nitrates in dried tea sort and infusions we concluded that about 50% of nitrates is released from dried tea to the infusion.