Nitrate-Nitrite, Vitamin C And In-Vitro Methemoglobin Formation From Some Vegetables

ABSTRACT

The content of nitrate, nitrite and Vitamin C in eleven samples of fresh vegetables were determined. The levels of nitrate were beyond here on recommended in six of the vegetables, namely: Celosia sp. Lactuca, sativa , Amaranthus hybridus, Brassica oleracea variety acephala, Talinum sp, Spinacia oleracea. Minute quantifies of nitrite were detected in Celosia sp and Daucus carota. With accompanying high concentration of Vitamin C (a reducing agent) present in Celosia sp. this vegetable may be a potential source of nitrite in foods. Effect of cooking caused less than 25% reduction in nitrate-nitrite content of the vegetables.

When an in vitro test of methemoglobin formation was carried out with extract from the samples, modified hemoglobin formed paralleled content of nitrate in the vegetables. It is suggested that caution must exercised in the use of some of these vegetables in infant foods as they may contribute to induction of methemoglobin.