Study On The Geographic Fingerprint Information And Identification Of Zhongning Wolfberry

As a type of traditional medicine and nutritional supplement,wolfberry is rich in nutrients that are benefit for humans,Zhongning wolfberry with geographical indication is very popular among consumers because of its good quality.But fake Zhongning wolfberry products frequently appear throughout the country,so it is important to develop a reliable and accurate geographical traceability method for authentic Zhongning wolfberry and promote the development of wolfberry industry.A total of 122 wolfberry samples and 100 soil samples were collected from Ningxia Hui autonomous region(Zhongning county and other counties around Zhongning),Gansu province and the Xinjiang Uygur autonomous region in 2014 and 2016.The concentrations of twenty elements(K,Mg,Fe,Ca,Zn,Cu,Mn,Al,Sr,Rb,Mo,Tb,Cd,Co,V,As,Cs,Pr,Dy and Gd)in wolfberry and soil samples were determined using inductively coupled plasma mass spectrometry(ICP-MS).The stable isotope ratios(C,N,H,O)of wolfberry samples were measured by isotope ratio mass spectrometry(IRMS).The near infrared reflectance(NIR)spectrum of wolfberry samples were analyzed using NIR spectrometer.And the data were subjected to different supervised chemometric approaches,such as analysis of variance,multiple comparison analysis,principal component analysis,discriminant analysis and correlation analysis.The study analyzed the differences of determined indicators in Zhongning wolfberry and wolfberry samples from other regions,and explored the feasibility of these techniques for the discrimination of Zhongning wolfberry;then discussed the influences caused by geology,soil environment,climate and variety.Furthermore,all indicators in wolfberry samples from different picking periods were compared,and the effective indicators were selected to establish discriminant model,then Zhongning wolfberry samples from another year were used in validation analysis to evaluate the stability of the model.Finally,the study assessed the effectiveness,applicability and economy of different techniques for the identification of Zhongning wolfberry to find effective techniques for authentic Zhongning wolfberry.The main conclusions are as follows:(1)The mineral concentrations and stable isotope ratios of wolfberry samples represented significant differences among regions,and the models build with these two techniques had satisfying results for the identification Zhongning wolfberry.The discrimination of near infrared reflectance spectroscopy was not very satisfactory.(2)The mineral concentrations and C,N,O stable isotope ratios and the NIR spectrum for origin identification of Zhongning wolfberry kept stable among different picking periods.(3)The mineral indicators like Mg,Ca,Mn,Fe,Co,Cu,As,Mo and C,N,O stable isotope ratios were effective when identified Zhongning wolfberry from different years,so these indicators were relatively effective and stable for authentic Zhongning wolfberry.(4)Mineral elements and stable isotope fingerprints were more effective in the determination of Zhongning wolfberry,and the cost is acceptable,so they were suitable for the identification of Zhongning wolfberry.The NIR spectrum analysis cost less,but its correct discrimination rate of Zhongning wolfberry still needs to be improved.