The Geographic Authenticity Technologies On Fangzheng Rice

Quality characteristics of rice is not only related to varieties,but also related to producing area conditions,including climate condition,soil and water condition.The regional characteristics of high quality rice are obvious.Some unscrupulous traders counterfeit geographical indication in order to seek exorbitant profit,thus damaging the interests of consumers.Therefore,it is of great significance to establish an effective identification method.The high throughput,high sensitivity and high accuracy spectrum of metabonomics make it possible to integrate biological samples and system information,and provide a new way of thinking on origin traceability.Metabolomics analysis method of rice is presented in this paper,and was applied to identification of the origin.Identification model was constructed combined with the mineral elements fingerprints analysis.The main contents are as follows:1.Fingerprint chromatography of rice was established by liquid chromatography/quadrupole time-of-flight-mass spectrometer(LC/Q-TOF MS).The extraction reagent,extraction method and instrument conditions were optimized to represent complete information of metabolites in rice sample.Methodological investigation was performed.Principal component analysis(PCA)and t test were performed using fingerprint chromatography acquired in both the positive ion mode and the negative mode.Each group was separated successfully,thus representing the difficulty among samples.15 biomarkers were screened out based on the loading plot.The metabolites were identified based on MS accurate mass and spectrometry fragmentation information of MS/MS,combined with database search and literature.6 compounds were found in the positive ion mode and 3 were found in the negative ion mode.Selected ion intensity trend plots of the most discriminating identified markers were performed to assess the distribution in different samples.Blind samples obtained from market were tested by the model with correct classification.2.The analysis of metabolic profiling of rice from different geographical origin by gas chromatograph/quadrupole time-of-flight-mass spectrometer(GC/Q-TOF MS)was applied to geographic authenticity identification of rice.Effects of derivatization reagents,derivatization temperature and time on the analysis of metabolites were investigated.The best result was obtained with condition which extracted with methanol/water(1:1),and derivatized with N-methyl-N-(trimethylsilyl)trifluoroacetamide / trimethylchlorosilane(MSTFA/TMCS 99:1)at45℃ for 1 h.10 highly matched metabolites were selected to assess the precision,stability and reproducibility of the method.Satisfactory results were obtained with relative standard deviations(RSD)which were lower than 9 %,confirming reliability of the method..Mass profilerprofessional(MPP)was used to filter differential compounds based on statistical method.Principal component analysis(PCA)was applied to classified the rice of different geographical origin significantly.Cumulative contribution rate of former 3 principal components reached85.23%,which could reflect the majority of quality information.Box-whisker plots of the most discriminating identified and highly matched markers were showed to assess the distribution in different samples.The partial least squares-discriiminate analysis(PLS-DA)prediction model was established,which 100% correct classification and 95.8% cross validation were achieved with confidence level between 70%-96%.This demonstrate the accuracy of model.Real samples were tested by the model with correct classification.The results showed that the forecasting model established for rice origin identification by the analysis of rice metabolic profile combined with PCA and PLS-DA method is feasible.3.The concentrations of 15 chemical elements(Na、Mg、Al、K、Ca、V、Cr、Mn、Fe、Cu、Zn、Ba、Mo、Ni and Cd)were determined using inductively coupled plasma mass spectrometry(ICP-MS).Samples from different geographical origin in Heilongjiang province were analyzed by ANOVA to study the difference of elements content.Principal component analysis(PCA)was applied to research the relationship between element and geographic origin.Samples were classified into 4 groups correctly.8 key variables(Mg、Ca、V、Cr、Fe、Ni、Ba and Cd)were confirmed by stepwise discriminant analysis(DA).The discriminant models were achieved with100% correct classification and 93.8% cross validation.The results showed that it is a feasible method to identify the origin of rice using multi-element analysis based on multivariate statistical analysis.