Study On Detection And Removal Method Of Nitrite In Aquatic Products

This dissertation presents three kinds of new spectrophotometry methods for determining nitrite in seafood.UV-VIS spectrophotometer is used for quantitative analysis of nitrite by employing different diazotization and coupling reagent.The optimal color conditions are investigated.There are their town applied object,merits and demerits in these three methods.Specific contents are as follows1、A new specreophptpmetery method is established for determination of nitrite in seafood.The method is based on a diazotion-coupling reaction between nitrite and P-amino benzene sulfuric acid then coupling with N,N-diethyl aniline to form an orange product.This method has simple operation,good selectivity,high sensitivity and little interference.The results comparing with the standard method are basically the same,also the reagents have lower toxicty than national standard method.2、The secend method proposed 2-chloro-4-nitroaniline as another diazotize reagent and hydrochloric acid naphthalene ethylenediamine as the coupling reagents.The samples are processed under the combine action of sodium hydroxide and zinc acetate,EDTA is used to conceal metal ions.This reaction can be carried out under room temperature and the time is short.The method can be used to determine trace nitrite in seafood.3、The principle of the third method is nitrite and 8-hydroxylquinoline happening chromogennic reaction under the alkaline conditions.The colored substances is determined by UV-VIS spectrophotometer,and then the content of nitrite is calculated.Under the best experimental conditions the absorbance and nitrite have a good linear relationship within the range of the concentration of nitrite is 0-7.0mg/L.The linear equation is Y=0.4553X-0.0105,the correlation coefficient is r=0.9981.The adwantage of this method is concealing metal ions under alkaline conditions.4、The method of nitrite scavenging in salted fish were studied,too.The scavenging effect of welsh onions,ginger,garlic extraction on nitrite in salted fish were studied.The result shows that the opimum ultrasonic hath temperature,sonication time were 60℃,40min.And the solid and liquid of welsh onions,ginger,garlic were 50g/100g,30g/100g,30g/100g.Under the best conditions,the scavenging rate of nitrite with welsh onions,ginger,garlic were 54.6%,56.6%,63.6%.When the extraction of garlic is not less then 50%,the scavenging rate of nitrite for the mixture were higher than that of the three kinds of material.The scavenging rate is the highest when the proportion of onions,ginger and garlic mixture extract is 1:4:5.After the salted fish were soaked in the mixture,the scavenging rate of nitrite were found in the range of 69.8%～95.5%.5、The purpose of this part is to use the spicy vegetable extract to remove nitrite in food,especially in seafood,blocking the formation of carcinogenic nitrosamines in the research.Focuses on extraction of garlic,shallot and ginger spice materials of active ingredients,active ingredients on nitrite removal effect.The ultimate goal is to develop effective remover of nitrite.The elimination rates of the different component from the scallion extracts to nitrite were determined using N-(1-naphthal-)ethylenediamine dihydrochloric spectrophotometry.Scallion extract different composition under the same conditions of saury clearance rate of nitrite.With each other is not the same method to extract the composition,extraction rate can be achieved respectively polysaccharide(0.48%),vitamin C(0.75%),flavone(0.38%),polyphenols(3.02%),organic sulfide(1.15%).The results show that the effective components of scallion,such as vitamin C,polysaccharides,polyphenols,flavonoids,organic sulfide,etc all can effectively remove the nitrite in the seafood,clearance of organic sulfide(80.04%)>flavone(72.90%)>vitamin C(32.13%)>polyphenol(24.90%)>polysaccharide(6.62%).Calculated by the composition of nitrite clearance IC50 alue concentration of ganic sulfide respectively organic sulfide(58.69 μg)<vitamin C(68.59μg)<flavonoids(155.62 μg)<polyphenols(200.80 μg)<polysaccharide(755 μg).The experiment for organic sulfur elements of nitrite removal,vitamin C and other theoretical support.