Study On The Differences Of Pesticide Residues In Watermelon From Different Producing Areas In Xinjiang And The Comprehensive Traceability Technology

The team conducted a preliminary study on the pesticide residue levels of watermelon samples from 10producing areas in Xinjiang,and the results showed that there were differences in the pesticide residue levels of watermelon samples from different producing areas.Therefore,this paper further expanded the research and evaluation area to 19 counties and cities.Based on the analysis of pesticide residues,4 stable isotopes,13 mineral elements and nuclear magnetic resonance correlation in watermelon samples collected from the above-mentioned production areas,the differences of watermelon quality and safety level in different production areas were carried out by a series of methods In order to clarify the distribution of pesticide residues in Watermelon in different producing areas,we should establish the Traceability Technology of watermelon producing areas in relatively high pollution areas,and provide support for the government's efficient supervision.(1)Taking 237 watermelon samples from 19 counties in Xinjiang(A-S)as the research object,the levels of pesticide residues in the samples were analyzed.On this basis,the single pollution index,Nemerow comprehensive pollution index and acute and chronic dietary risk were used to evaluate the pollution level of pesticide residues in different production areas.15 kinds of pesticide residues were detected in all watermelon samples,and the detection rate was 46.84%.Among them,pyrimethanil,acetamiprid and carbendazim were the main pesticide residues,accounting for more than 10%;There were 7 and 2 samples in E city and D County,1 in L City and 1 in N county,and 100%of the samples in the other 15 production areas were in the safe level.The results show that:there is a phenomenon of pesticide detection in the samples,but the residual risk is at a safe level.The degree of pesticide residue pollution in watermelon is different in different producing areas,and the degree of pesticide residue pollution in E city,D County,L City and N county is relatively high,which should be regarded as the focus area of watermelon pesticide residue.(2)Four stable isotope ratios of 237 watermelon skin samples were analyzed.On this basis,the discriminant model of watermelon producing areas in Xinjiang was studied and constructed by single factor analysis of variance(ANOVA),least significant difference multiple comparison(LSD)and partial least squares discriminant analysis(PLS-DA).The results showed that the stable isotope ratios of watermelon samples from different areas in Xinjiang were different.The difference of ¹⁸O and ²H was significant,?¹³C??¹⁵N is smaller.The results of PLS-DA analysis showed that the separation effect of M,G,h and I was relatively good.Among the four production areas that need to be focused on,E and D can be clearly distinguished,but L and N can not be significantly distinguished from other production areas.This shows that only using stable isotope technology can effectively distinguish E and D producing areas,but it can not distinguish L and N in relatively high pollution areas from other producing areas.(3)In order to solve the problems mentioned in the second part,based on the analysis of 13 mineral elements in 237 samples,combined with stable isotope data,the origin of watermelon in Xinjiang main producing areas was identified by ANOVA,LSD and orthogonal partial least squares discriminant analysis(opls-da).The results showed that the samples from different producing areas could be distinguished clearly.The four production areas that need to be focused on are also significantly separated from the rest.Among them,hydrogen and oxygen isotope is an important variable to distinguish watermelon from different producing areas.The overall discrimination accuracy of the samples was 66.11%,and the discrimination accuracy of L and N producing areas that need to be focused on was not ideal.(4)By scanning 237 watermelon samples in Xinjiang,the characteristic wavelength and shift point were extracted.The results show that the discrimination model of stable isotope combined with mineral element technology can be used to separate all the samples in E producing area,while the discrimination model of stable isotope combined with nuclear magnetic resonance technology is more suitable for D producing area,and the discrimination results of N and L producing area are not ideal.The other production areas can also be distinguished by four kinds of discriminant models.To sum up,different producing areas are suitable for different identification techniques,which can be selected according to the needs of brand protection in target producing areas.