INRA, Montpellier SupAgro, UMR 1083 SPO Sciences pour l'Œnologie, 2 Place Viala, 34060 Montpellier, France.
INRA, Montpellier SupAgro, UMR 1208 IATE Ingénierie des Agropolymères et Technologies Emergentes, 2 Place Viala, 34060 Montpellier, France.
J Agric Food Chem. 2020 Mar 11;68(10):2917-2926. doi: 10.1021/acs.jafc.9b00497. Epub 2019 May 1.
An improved analytical depolymerization method for characterizing condensed tannins was developed with menthofuran (3,6-dimethyl-4,5,6,7-tetrahydro-1-benzofuran) as the nucleophilic trapping reagent. Herein, menthofuran was compared with routinely used nucleophiles, phloroglucinol and 2-mercaptoethanol. At 30 °C and in the presence of 0.1 M HCl, menthofuran displayed the outstanding ability to enable the fast and full depolymerization of procyanidin B2 using only a 1:1 molar ratio of both reactants. Under the same conditions, phloroglucinol and 2-mercaptoethanol led to a reaction equilibrium with significantly lower conversion yields. Application to commercial tannin extracts showed that a menthofuran-to-extract weight ratio of 1 gave the same yields of procyanidin constitutive units as 10-fold higher molecular equivalent phloroglucinol and 100-fold 2-mercaptoethanol. Finally, guidelines for implementing the menthofuran depolymerization method are proposed to assess the tannin content and composition of extracts as well as of plant materials without prior extraction.
一种改进的分析性解聚方法，用于对缩合单宁进行特征分析，其中间体捕获试剂为甲基糠醛（3,6-二甲基-4,5,6,7-四氢-1-苯并呋喃）。在此，将甲基糠醛与常用的亲核试剂间苯三酚和 2-巯基乙醇进行了比较。在 30°C 和 0.1 M HCl 存在下，仅使用反应物摩尔比为 1:1，甲基糠醛就显示出使原花青素 B2 快速完全解聚的出色能力。在相同条件下，间苯三酚和 2-巯基乙醇导致反应平衡的转化率明显较低。该方法应用于商业单宁提取物表明，当甲基糠醛与提取物的重量比为 1 时，原花青素结构单元的产率与 10 倍高摩尔当量的间苯三酚和 100 倍的 2-巯基乙醇相当。最后，提出了使用甲基糠醛解聚方法的指南，以评估提取物以及未经提取的植物材料的单宁含量和组成。
