The Study On Determination Method And Cumulative Factors Of Nitrate And Nitrite In Vegetables

On the basis of the dual-wavelength UV spectrophotometry, we studied on the direct determination of nitrite and nitrate by subtractive UV spectrophotometry in vegetables. By the spectrogram, it was known that nitrite absorption peak is at 210 nm and nitrate absorption peak is at 203 nm, they interfere with each other and are very close. It was needed to eliminate the mutual influence in determination. In general, the concentration of nitrate is bigger than the concentration of nitrite in vegetables. In this test, the determination of nitrate and nitrite is at 210 nm.We applied the UV spectrophotometer determined content of nitrate and nitrite in vegetable. The most important infection factors were complicated component of vegetable especially disturb of organic matter besides each other disturber of most absorb wavelength of them. Consequently the experiment based on predecessor work. We improved UV spectrophotometer method to determine content of nitrate and nitrite in vegetable. At the same time, we systematically discussed infection factors in test, and then acquired better effect. To eliminating disturbance of orgnic and complex matter, except the familiar method, we determined the content of nitrate and nitrite regarding the water that has wiped off nitrite and nitrate as the reference solution; to determine the content of nitrate regarding the vegetable juice that has wiped off nitrite as the reference solution. Because the components of the reference solution and samples were identical except of nitrite, so it was conducive to the nitrite determination by eliminating the interference, the accuracy and the precision were improved.The characteristics of the determination method were simple and accurate because it was not needed to add the organic precipitator that would be disturbed the determination. The test steps were simplified greatly, the accuracy and precision of the method are high. This method can satisfy large quantities of samples need on analysis and test.Vegetable types were the main factors to accumulation of nitrate and nitrite by the study on the accumulated factors in vegetables. The cumulation of nitrate and nitrite were affected from the external factors in the same kind of vegetable, such as the different picking time, the different washing ways, the different cooking utensils, the different storage temperature, and the different storage methods. The conclusion could provide the data and method which were scientific, accurate, timely and rapid to the environmental department, the health supervision department, and so on. The study focused on the formation mechanism of nitrite and content changes in the process of pickled vegetables. It was discussed that salt concentration, temperature, acidity and sugar content influenced on nitrite content of and microwave technology applied in this process. To improve the pickling process and effectively reduce the nitrite content, this paper provides a theoretical basis to make pickled vegetables into better quality and health care products.