Study on the effect of boiling and freezing process on nitrate and nitrite levels in abundant consumed vegetables

Vegetables is one of the most important expose sources of nitrite and nitrate in human''s diet. The aim of this study is evaluation of boiling and freezing process on nitrite and nitrate levels in commonly consumed vegetables. It was the descriptive – analyzed study. 180 vegetable samples were taken from Kermanshah markets، randomly. Nitrite and nitrate concentration was determined by Greece- Ilosoay method. Then، freezing and boiling process were carried out on samples and again، nitrite and nitrate levels were measurement. The mean differences were analyzed by using ANOVA and SPSS program. The amounts of nitrite and nitrate in many samples had significant differences (p<0. 05)، depending on type of process and product. Increase in time of freeze storage from 1 to 3 month resulted in increase in amounts of nitrate and nitrite in many samples while، 9 month freezing storage decreased nitrate and nitrite levels. Boiling process increased nitrate and nitrite levels in several vegetables، such as scallion and decreased it for instance، in garlic chives Long term freezing process is a suitable method to reduce nitrate and nitrite levels in vegetables. Regarding to daily consume of vegetables and its positive effects on public health، quality control of this product and studying the other food processing is very important.