Research On The Dairy Detection By The Nonlinear Chemical Fingerprint Technology

As the development of chinese society, people’s demand for dairy products dramatically increases according to their understanding of its nutrition. However, people in our country have no confidence on native dairy products because of the safety accidents accured occasionally, which required us to strengthen the testing system to ensure the safety of our country’s dairy products,it also has an important significance and broad prospects in studying the quality control and adulteration identification. The findings are as follows.In the first chapter of the paper, a brief introduction was made about the current status of food safety in our country, the development of dairy industry and several risks and hazards in food safety of our country were analyzed. Also, several common reaction mechanism of nonlinear chemical reaction of nonlinear chemical fingerprint were emphasized and discussed. Besides, a summary was made about the application of nonlinear chemical fingerprint in the Monitoring of food and medicine.The basic infomation of nonlinear chemical fingerprint was analyzed about the system of " H++Fe2++BrO3-+CH2(COOH)2" in the second chapter. Every chemical reaction in process was represented by a specific equation, after that, the relevant chemical kinetics curve E-t of the nonlinear chemically reaction, which was abtainde from the functional relations between the potential of working electrode(E/V) and the reaction time(t/s), was deduced. Further more, several factors were simply introduced and analyzed, such as similarity degree of system, euclidean distanced(x,y), cosine cosa, and related coefficient(r), by doing so, similarity degree of system was choiced as the final mothod of calculation and evaluation.Durign the chapter 3, the chemical reaction system used in this paper was optimized detailedly. At first, basis of single-factor test, detection does, operating temprature, and the concentration of major system agents were determined with single-factor tests, and then the response surface test was developed them. During the response surface test, four factors three levels were chosed:temprature(40 ℃ 45℃and 50℃), concentration of sulfuric acid(0.75mol/L, 1.0mol/L and 1.25mol/L), concentration of malonic acid (0.75mol/L, 1.0mol/L and 1.25mol/L),the concentration of sodium promate(0.6mol/L,0.8mol/L and 1.0mol/L). Results showed that the best conditions for milk powder detection were as follows:stirring speed800r/min,the detection does 1.0g、temprature 48 ℃, concentration of sulfuric acid 1.15mol/L, concentration of Malonic acid 1.0mol/L, concentration of sodium bromate 0.8mol/L, concentration of ferrous sulfate 0.1mol/L. The repeatability of nonlinear chemical fingerprinting under the optimized condition of chaper 3 was discussed, and then this technology was researched to identify milk powders with diffrent brands and types.In chapter 4, the Parameters information of quantitative,which obtained from fingerprint, was mainly studied to combine the doping content, then general model was structured out for analysing the cluster content of adulteration quantitative in milk powder under; by this way, it could be judged whether the milk powder was adulterate or not. The doping quantitative analysis and quality evaluation of goat milk powder from adulterated by adding milk powder can be conducted by the method of nonlinear chemical fingerprint, which has a detection limit of 1.0× 10-4g/g～1.3×10-4g/g. This method for testing the milk powder is practicable, satisfiable, accurate and reproducible.In chapter 5, the applicaton of this testing method was introduced, which is about the identification of single-component starch adulterating in the milk powder. Whether the milk powder was adulteratedor not was judged by intuitive features of the fringerpriints at first; with that, the amounts of adulteration in samples were calculated,byfitting the linear relation between quantitative information of the prints parameter and the amount of adulteration; finally, the result of this method was discussed, which was applicated in analysising adulteration in milk powder. The results showed that the detection limit was 1.1× 10’4g/g～1.3×10-4g/g, which obtained from using nonlinear chemical fingerprints to analysis the doping quantity and evaluate the quality of milk powder. Therefore, this method is available, and has a high accuracy and precision.