Investigation of the effects of processes applied on spinach plant on nitrite and nitrate content

In this study, the effects of fertilization, different processes and storage on nitrate and nitrite levels in spinach (Spinacia oleraceae L.) were tried to be determined. The nitrate and nitrite contents of spinach grown according to 4 different fertilization amounts (0; 7,5; 15 and 20 grams/m2) using urea 46% nitrogen fertilizer for two consecutive years were determined. In addition, spinach is dipped and boiled by steaming; then, the effect of technological processes such as freezing, drying and canning on these components was tried to be determined. For the purpose of determining the effect of storage, samples are collected for 12 months; frozen samples at -18℃; dried samples were stored at +4 and canned samples were stored at room temperature; the amount of nitrite and nitrate in the samples were determined at 0, 4, 8 and 12 months. In the study, nitrate and nitrite contents of spinach samples were analyzed by high pressure liquid chromatography (HPLC) method. According to the recovery studies conducted to determine the method parameters; the recovery rate determined for nitrate was 101,23% on average and the recovery rate determined for nitrite was 97,13% on average. Among the method parameters, the LOD value is 0,001 mg/kg for nitrate and 0,002 mg/kg for nitrite; LOQ value was calculated as 0,004 mg/kg for nitrate and 0,006 mg/kg for nitrite. The nitrate amounts in spinach samples planted in the 1st year were 72,05 mg/kg, respectively, for 0 g/m2 fertilizer applied; 165,43 mg/kg for those where 7,5 g/m2 fertilization was applied; 203,41 mg/kg for 15 g/m2 fertilizer and 308,43 mg/kg for 20 g/m2 fertilizer. In spinach samples planted in the 2nd year, nitrate amounts were 85,45 mg/kg in those with 0 g/m2 fertilizer; 123,07 mg/kg for those with 7,5 g/m2 fertilization; 208,5 mg/kg for 15 g/m2 fertilizers and 297,86 mg/kg for 20 g/m2 fertilizers. These values are far below 3500 mg/kg, which is the maximum nitrate amount required in fresh spinach according to the Turkish Food Codex Contaminants Regulation. No nitrite could be detected in fresh spinach samples (