Skolkovo Institute of Science and Technology, Nobel St. 3, Moscow 143026, Russia.
Institute for Information Transmission Problems, Bolshoy Karetny per. 19, build.1, Moscow 127051, Russia.
Genes (Basel). 2019 Feb 7;10(2):122. doi: 10.3390/genes10020122.
Plants are widely used for food and beverage preparation, most often in the form of complex mixtures of dried and ground parts, such as teas, spices or herbal medicines. Quality control of such products is important due to the potential health risks from the presence of unlabelled components or absence of claimed ones. A promising approach to analyse such products is DNA metabarcoding due to its high resolution and sensitivity. However, this method's application in food analysis requires several methodology optimizations in DNA extraction, amplification and library preparation. In this study, we present such optimizations. The most important methodological outcomes are the following: 1) the DNA extraction method greatly influences amplification success; 2) the main problem for the application of metabarcoding is DNA purity, not integrity or quantity; and 3) the "non-amplifiable" samples can be amplified with polymerases resistant to inhibitors. Using this optimized workflow, we analysed a broad set of plant products (teas, spices and herbal remedies) using two NGS platforms. The analysis revealed the problem of both the presence of extraneous components and the absence of labelled ones. Notably, for teas, no correlation was found between the price and either the absence of labelled components or presence of unlabelled ones; for spices, a negative correlation was found between the price and presence of unlabelled components.
植物被广泛用于食品和饮料的制备，最常见的形式是干燥和研磨的植物部分的复杂混合物，如茶、香料或草药。由于潜在的健康风险来自未标记成分的存在或声称成分的缺失，因此对这些产品进行质量控制非常重要。分析此类产品的一种很有前途的方法是 DNA 代谢组学，因为它具有高分辨率和灵敏度。然而，这种方法在食品分析中的应用需要在 DNA 提取、扩增和文库制备方面进行多项方法学优化。在本研究中，我们提出了这些优化方案。最重要的方法学结果如下：1）DNA 提取方法极大地影响扩增成功率；2）代谢组学应用的主要问题是 DNA 纯度，而不是完整性或数量；3）可以使用对抑制剂具有抗性的聚合酶扩增“不可扩增”的样品。使用这种优化的工作流程，我们使用两个 NGS 平台分析了广泛的植物产品（茶、香料和草药制剂）。分析揭示了存在外来成分和缺失标记成分的问题。值得注意的是，对于茶来说，标记成分的缺失或未标记成分的存在与价格之间没有相关性；对于香料，价格与未标记成分的存在呈负相关。
