Study of the effects of ionic strength, pH and temperature of washing solution on nitrate percentage in fresh vegetables

In this study, we try to evaluate the effect of ionic strength, pH and temperature of washing solutions on nitrate percentage in many leafy and root vegetable. For this purpose three edible solutions including NaCl as high ionic strength solution, baking soda (NaHCO3) as basic solution and vinegar as acidic solution selected as nitrate losing agents for leafy vegetables (mint, basil, savory, tarragon, parsley, coriander, cress, radish and chives) and the effect of temperature evaluated using warm water (70 -100 ˚C) on nitrate percentage in root vegetables (potato and onion). Nitrate percentage in vegetables changed with different patterns. High ionic strength increased leafy vegetable nitrate percentage in wide rang (20.25 - 85 %(w/w)), pH increasing by baking soda solution increased nitrate percentage of group 1(Mint & Basil) leafy vegetables (33 %(w/w)) and decreased it in other groups partially (0.22 - 6.2 %(w/w)). However, pH decreasing by vinegar solution decreased nitrate percentage in all cases (14.6 - 41 %(w/w)). Optimum concentration of vinegar solution and treatment time in this solution, for maximum nitrate losing were 20 % (w/w) and 10 minutes, respectively. In the second part of this study, effect of solution temperature on nitrate percentage of root vegetables (potato and onion) was evaluated. Results show by this pretreatment nitrate percentage decreased 68.6 %(w/w) about potato and 26.6% (w/w) about onion. The important advantage of this study is vegetables nitrate percentage decrease, while the freshness and safety of these products preserved.