| Food geographical origin traceability system is a powerful approach to ensure foodsafety, protect geographical indication and strengthen consumers' confidence. Analyses ofstable isotope ratio, mineral element content and near infrared reflectance spectroscopy areconsidered as effective techniques for food geographical origin traceability. The objective ofthis paper was to investigate the potential of these fingerprint techniques for geographicalorigin traceability of lamb meat in China. Lamb meat, wool, their feeds and drinking wateroriginating from five major lamb meat producing regions of China including Alxa League,Xilin Gol League and Hulunbuir City in Inner Mongolia, Heze City in Shandong Provinceand Chongqing City were collected for the analysis. δ13C, δ15N and δ2H values of thesesamples were determined by isotope ratio mass spectrometry(IRMS), the contents of Al,Ca,V,Cr,Mn,Fe,Co,Ni,Cu,Zn,As,Se,Ag,Sb,Ba,Tl,Pb,Th,U,Mg,K,Cd and Mo in lamb meat were measured by inductively coupled plasma mass spectrometry(ICP-MS), and near infrared spectra of lamb meat were scanned using NIR spectrometer.Multivariate statistical methods including ANOVA, principal component analysis (PCA),cluster analysis (CA), and linear discriminant analysis (LDA) were used for data analysis. Thestudy mainly analyzed the characteristics and differences of stable isotopes, element contentsand NIR fingerprints in lamb tissues from above different regions, discrimination power ofthese techniques for lamb meat geographical origin assignment, and the relationship of stableisotopes, element contents and NIR fingerprints in lamb tissues with their feedingenvironment.Lamb transfer-feeding model experiment was designed to investigate the changemechanisms of traceability information of stable isotopes, element contents and NIR in lambtissues, and to further confirm the validity and stability of these techniques for tracing lambmeat geographical origin. Carbon, nitrogen and hydrogen isotope compositions, contents of57elements, and NIR fingerprints in muscle, heart, liver, lung and wool of lamb that weretransfer-fed in different feeding periods at the same region and in different regions weredetermined, and their changes with the variations of origin, feeding periods and feeding typewere analyzed. In addition, the differences of these indicators in different organs and tissues of lamb were compared, and the suitable indicators for geographical origin traceability wereestablished. The main conclusions were as follows:(1) There were significant differences of stable isotopes, element contents and NIR inlamb tissues according to their geographical origin. Each region had its unique fingerprint.The total correct classification rate over85%was obtained according to the geographicalorigin using any of these techniques, which indicated the feasiablity and validity of thesemethods for tracing the lamb meat origin. The combination of stable isotopes and mineralelements notablely improved the correct classification rate and had a better traceability effecton lamb meat origin than those single methods. The indicator system of each method for lambmeat origin traceability was as follow: the combination of δ13C, δ15N and δ2H values forstable isotope analysis, the contents of Be,Cr,Mn,Fe,Cu,Zn,As,Sb,V,Ba,Ni andNa for mineral element analysis, and δ2H,δ15N,V,Cr,Mn,Tl and Zn for analysis of stableisotopes combined with mineral elements.(2) Carbon, nitrogen and hydrogen isotope ratios in lamb tissues and organs hadsignificant differences between different regions and between different feeding periods. Theywere more affected by origins than feeding periods and their interaction. This result confirmedthe validity of stable carbon, nitrogen and hydrogen isotopes for lamb meat origin traceabilty,and seasonal variation was also should be considered.(3) There were different turnover rates of stable isotopes in lamb tissues and organs. Theturnover of carbon, nitrogen and hydrogen isotopes in in internal tissues such as liver, lungand heart were faster than those in defatted muscle and wool. It's implied that the suitabletissues can be chosen for lamb meat origin according to the feeding time. There were alsosignificant differences of stable isotopes between the different tissues. The carbon isotope intissues had no significant difference except for its higer existance in wool than in liver. Thenitrogen isotope in tissues had no significant difference except for its higer existance in heartthan in defatted muscle. The order of hydrogen isotope in tissues from high to low were wooland liver> heart and lung> defatted muscle. There were correlations of carbon, nitrogen andhydrogen between the different tissues despite their differences.(4) The distinct element fingerprint features were found in lamb tissues and organs fromdifferent regions, with Li,Ni,Mo,Cs,Se,Cu,Rb,As,Zn,Mn and Fe in defatted muscle,Be,In,Sb,Dy,Li,Sc,Cs,Se,Sn,Rb and As in heart, Y,Nb,Sb,La,Ce,Pr,Nd,Sm,Eu,Gd,Tb,Dy,Ho,Er,Yb,Th,Li,Cs,Se,Rb,Mn and K in liver, andCd,Cs,Rb,Ti,Be,In,Sb,La,Ce,Pr,Nd,Gd,Tb,Dy,Ho,U,Li,Sc,Ni,Mo,Pb,Bi,Se,Sn,Zn,K and Mg in lung. Elments with no significant difference were alsoexisted in lamb tissues and organs from the different feeding periods within the same origin, which were relatively less in Taipusiqi than those in Yangling Zone. The element that hadsignificant difference between the regions but no significant difference between feedingperiods can be used as tracing indicators.(5) The element fingerprints in different tissues and organs had distinct characteristics,resulting in different referred indictors for origin traceability, with Tb,Rb,Mo and Fe formuscle, Be,Gd,Lu,Rb,Cs and As for heart, Eu,Ce,Dy,Yb and Cs for liver, Be,In,La,Gd,Ho,Th,Sc,Pb,Bi,Rb and Cs for lung. Rb and Cs were the common tracingindicators for all tissues and organs.(6) There were both significant differences of NIR fingerprints in lamb tissues andorgans between their origins and between their feeding periods, which indicated that theseasonal variation should be considered when using NIR fingerprint for origin traceablity. Inaddition, NIR fingerprints of lamb muscle, heart, liver and lung had similar differencesaccording to different origins and different feeding period, which domenstrated that all thesetissues can be used for lamb meat origin traceability.(7) The statistics methods including variance analysis, principal component analysis,cluster analysis and discriminant analysis were essential tools for selecting the indicators andestablishing the discriminant models in lamb meat origin traceability. |
