title: [Identification of tea from different regions using X-ray fluorescence].
abstract: The existence of fake tea from non-origin seriously impacts on the credibility of the famous tea. A method was developed to identify tea from difference regions on the basis of the fact that the content of heavy metals in different origin tea is varied by using X-ray fluorescence technique and pattern recognition technique. Samples from different origins were grouped respectively, and their X-ray fluorescence spectra were acquired, and then the principal components of these spectral data were calculated, and the average of the principal components of each group was used as the center of each group. The Mahalanobis distance value between a sample and the center of a group were calculated, when the Mahalanobis distance value reached minimum, the sample was classed to current group, and in this way, a sample was identified. A Niton 792 portable X-ray spectrometer was used to class 120 tea samples from Anji, Jinhua, Hangzhou and Taizhou, in zhejiang province of China. It was found that the spectra between 3 and 13 KeV and the first 4 principal components give enough information for the identification of tea from different regions,and the rate of error was 4.2%.
authors.affiliation: College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310029, China. xqrao@zju.edu.cn
authors.forename: Xiu-Qin
authors.initials: XQ
authors.lastname: Rao
authors.forename: Yi-Bin
authors.initials: YB
authors.lastname: Ying
authors.forename: Hai-Bo
authors.initials: HB
authors.lastname: Huang
authors.forename: Zhou
authors.initials: Z
authors.lastname: Shi
authors.forename: Lian-Qing
authors.initials: LQ
authors.lastname: Zhou
mesh_terms: D028241:Camellia sinensis / Q000737:chemistry* / Q000145:classification*; D005504:Food Analysis / Q000379:methods*; D019216:Metals, Heavy / Q000032:analysis; D025341:Principal Component Analysis; D013052:Spectrometry, X-Ray Emission; D013662:Tea / Q000737:chemistry* / Q000145:classification*
chemical_list: D019216:Metals, Heavy; D013662:Tea