Content Evaluation on Nitrates and Nitrites in Local and Imported Vegetables

Research were conducted on samples of lettuce, spi nach and root from Cluj-Napoca markets and supermarkets. The obtained values fall in maximum admitted limits permitted by applicable law regarding the content of nitrates, l ocal samples (greenhouse and garden) with values lower than the import samples. Introduction Nitrates as such have a low toxicity, but by reduci ng them into the organism, it generates nitrites. Nitrites have dire ct toxicity, manifested by oxidation of hemoglobin into methemoglobin, respectively indirect toxicity due to the participation of nitrites to the formation of nitrosamines. Nitrate toxicity is manifested by its ability to transform into nitrosamines; nitrosamines can be fo rmed in both food products (exogenous origin), during their preserving, and digestive sys tem (endogenous origin), especially in the stomach (Santamaria et.al ., 2006). Nitrates concentrations in plant products depend on climatic conditions, plant characteristics and soil properties where grown: pl ant size, plant age, air temperature, humidity, growing period, light intensity and type of fertilizer, time of harvest, storage conditions and storage, etc. (Santamaria et.al ., 2006). Some of the vegetables which accumulate large quantities of nitrates belong to Brassicaceae (rocket, radish, mustard, etc.), Cheno podiaceae (beet, spinach), Amaranthaceae (Amarathus), Asteraceae (lettuce) and Apiaceae families (celery, parsley). (Santamaria et.al . 2006). Nitrates concentration decreases as follows: stems> leaves> root> blossom> tuber> bulb> fruit> seed. It results that whole eaten plan ts (root, stem and leaves) lead to a higher intake of nitrates than plants whose edible parts a re only the fruits.(Santamaria et al., (1999) Aims and objectives. The purpose of this study was to evaluate the cont ent of nitrates and nitrites in home-grown and imported vegetables products. The objectives were the establishment of the working matrices and the n itrate-nitrite determination in the matrices chosen by modified Griess method. Materials and methods. The vegetable matrix was consisted in 8 lettuce samples and 8 spinach samples grown in greenhouse and garden, harvested at different times of the year, and 8 roots samples (carrots, parsley, parsni p and celery) from both home-grown and import production. Spectrophotometric method consisted in nitrite dosi ng, by measuring color intensity at 520 nm of the azo formed compound after the reaction of dissolution between the sulphanilic acid and the nitrites from the aqueous extract of the sample and coupled with alpha-naphtylamine. To a new portion from the aqueous extract, nitrates are reduced to nitrites with metalic cadmium and the total nitrite content is determined. The difference between the total nitrites content and the original nitrites content are the nitrates. (STAS 9065 /2002).