西瓜稳定同位素与多元素特征分析及其产地溯源技术研究

本研究旨在利用稳定同位素与多元素分析技术结合化学计量学统计方法,开发不同省份西瓜产地溯源新策略。通过元素分析仪-同位素比质谱和电感耦合等离子质谱测定新疆、山东、广西、海南等产地的73份西瓜样本的碳、氮、氢、氧稳定同位素比值(δ¹³C、δ¹⁵N、δ²H、δ¹⁸O)与16种矿物元素含量(Na、K、Ca、Sr、Ba、Pb等)。单因素方差统计分析表明,δ¹³C、δ¹⁵N、δ²H、δ¹⁸O值与Na、K、Ca、Cr、Mn等元素含量特征在各省份西瓜样本间具有显著差异(P<0.05),但单一变量不足以将4个产地的西瓜完全进行区分。通过典则判别分析进行多变量统计分析,提取特征变量,构建线性判别函数,可以实现4个省份西瓜样本的原产地区分。该方法对新疆、山东、海南样本判别准确度高达100%,而广西样本判别率为71.4%,误判为海南产地概率为28.6%。由此可知,该策略能够实现大尺度地理空间的西瓜产地溯源,为其产地标识确证和优质品牌保护提供了有效的技术手段。

Study on the Stable Isotope and Multi-Element Analysis of Watermelon and Its Origin Traceability

This study is aimed to develop a new strategy for the origin traceability of watermelon in different provinces by combining stable isotopic and multi-elemental analysis with chemometrics. 4 stable isotope ratios (δ¹³C, δ¹⁵N, δ²H, δ¹⁸O) and 16 multi-elemental contents (Na, K, Ca, Sr, Ba, Pb, etc.) of 73 watermelon samples collected from Xinjiang, Shandong, Guangxi and Hainan, were detected by element analyzer-isotope ratio mass spectrometry (EA-IRMS) and inductively coupled plasma mass spectrometry (ICP-MS), respectively. One-way analysis of variance (ANOVA) of each variance indicated that value of δ¹³C, δ¹⁵N, δ²H, δ¹⁸O and the contents of Na, K, Ca, Cr, Mn in watermelon samples between provinces were significantly different (P<0.05). However, single variable was still not enough for classifying all samples from 4 provinces. In this context, canonical discriminant analysis (CDA) was applied for multi-variate statistical analysis, which can extract characteristic variables from all variables together and build new linear discriminant functions for classifying samples from 4 provinces. The discriminant accuracies of watermelon samples are up to 100% for Xinjiang, Shandong, Hainan, while only 71.4% for Guangxi, the possibility of which mis-discriminated as Hainan was 28.6%. Therefore, the strategy could realize the origin traceability of watermelon between large-scale geographical regions, which would provide an effective technique for the verification of origin label of watermelon and the protection of product origin of for premium brand.