基于稳定同位素与稀土元素指纹特征的大桃产地判别分析

Discriminations of the Geographical Origin of Peach Based on Stable Isotope and Rare Earth Element Fingerprint Characteristics

研究建立大桃产地判别技术,为保护地理标志产品、追溯原产地来源提供理论依据。本研究采集河北省顺平县、乐亭县、永清县和北京市平谷区共4个产地的92份普通大桃样品,利用元素分析-稳定同位素质谱仪测定大桃中稳定性碳、氮、氢、氧同位素比值,利用电感耦合等离子体质谱仪测定16种稀土元素含量,结合多重比较分析和一般判别分析建立大桃的产地判别模型。多重比较分析结果表明,平谷大桃的氮同位素与其他产地差异显著(P<0.05),平谷、顺平丘陵山区与乐亭县大桃的碳同位素比值差异显著(P<0.05),稀土元素铈、铕、钆和铒含量的地域分布差异最为明显;根据多重比较分析结果,将4种稳定同位素(δ13C、δ15N、δ2H和δ18O)结合8种稀土元素作为变量(钇、铈、铕、钐、镨、钕、钆和铒)进行一般判别分析,确定3个具有显著相关性(P<0.05)的判别函数,以此建立的判别模型对不同产地的大桃原始样本回代检验和交叉检验的整体正确判别率分别为97.8%和95.7%。利用稳定同位素和稀土元素指纹特征结合化学计量学方法对小空间尺度下的大桃产地判别具有可行性。

A method for geographical origin discrimination of peach was established to provide technical support for the protection of geographical indication products and for tracing the geographical origin of agricultural products.Ninetytwo samples of common peach cultivars were collected from four producing areas:the counties of Shunping,Laoting and Yongqing in Hebei Province and Pinggu district,Beijing in this study.The stable carbon,nitrogen,hydrogen and oxygen isotope ratios in peach were determined by elemental analysis-isotope ratio mass spectrometry.Inductively coupled plasma mass spectrometry was used to determine the contents of 16 rare earth elements.Multiple comparative analysis and general discriminant analysis were performed to establish a discriminant model for identifying the geographical origin of peach.Multiple comparative analysis showed that there were significant differences in nitrogen isotopes between Pinggu grown peach and those from other producing areas(P<0.05);significant differences were found in carbon and oxygen isotope ratios between peaches grown in hilly regions(Pinggu and Shunping)and those grown in plain regions(Laoting and Yongqing)(P<0.05),and the contents of the rare earth elements Ce,Eu,Gd and Er showed the most significant difference among different producing places(P<0.05).According to the results of multiple comparative analysis,four stable isotopes(δ13C,δ15N,δ2H andδ18O)and eight rare earth elements(Y,Ce,Eu,Sm,Pr,Nd,Gd and Er)were selected for general discriminant analysis.Three discriminant functions with significant correlations were determined(P<0.05).The overall correct discrimination rates for original peach samples from different geographical origins in back substitution and crossvalidation test were 97.8%and 95.7%,respectively.Conclusively,stable isotope and rare earth element fingerprint analysis combined with chemometrics is feasible to identify the geographical origin of peach in small spatial scale.