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首页> 外文期刊>Journal of mass spectrometry: JMS >UPLC-ESI-MS study of the oxidation markers released from tannin depolymerization: Toward a better characterization of the tannin evolution over food and beverage processing
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UPLC-ESI-MS study of the oxidation markers released from tannin depolymerization: Toward a better characterization of the tannin evolution over food and beverage processing

机译：UPLC-ESI-MS研究单宁解聚释放的氧化标记物：更好地表征单宁在食品和饮料加工过程中的演变

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Condensed tannins take an important part in the sensory quality of food and beverage. Sensory analyses are usually carried out with various tannin fractions isolated from food or beverage, and their interpretation are limited by the lack of knowledge in the fine and accurate molecular composition of the tannin fractions. Besides, the studies of the chemical reactivity conducted in model solutions with 'simple' flavanols allow a better understanding of their evolution pathways, but they cannot take into account their reactivity as polymers, specifically regarding oxidation. In particular, competition between intramolecular and intermolecular reactions may strongly impact on the tannin structures (size, branching and conformation) and consequently on their properties. An ultra-performance liquid chromatography-mass spectrometry electrospray ionization mass spectrometer analytical method was thus developed in order to identify oxidized tannins generated by autoxidation. Given the difficulties to separate and detect tannins with high DP, samples were depolymerized by chemical depolymerization prior to analysis. Since the linkages created by oxidation are not cleavable in the usual depolymerization conditions (contrarily to the original interflavanic linkages), specific oxidation residues are released from tannins structures after their autoxidation. Oxidation markers of both intermolecular and intramolecular mechanisms have been identified; these are mainly dimers and trimers, more or less oxidized, and some contain additional hydroxyl groups. Furthermore, the nature of the subunits (extension vs terminal) making up these dimers and trimers was clearly established.
机译：单宁浓缩在食品和饮料的感官品质中起着重要的作用。感官分析通常使用从食品或饮料中分离出来的各种单宁级分进行，其解释因缺乏对单宁级分精细而准确的分子组成的了解而受到限制。此外，在具有“简单”黄烷醇的模型溶液中进行的化学反应性研究可以更好地理解其演化途径，但不能考虑其作为聚合物的反应性，尤其是在氧化方面。特别地，分子内和分子间反应之间的竞争可能强烈影响单宁结构（大小，分支和构象），进而影响其性能。因此，开发了一种超高效液相色谱-质谱电喷雾电离质谱分析方法，以鉴定自氧化产生的氧化单宁。由于难以分离和检测具有高DP的单宁酸，因此在分析之前通过化学解聚将样品解聚。由于在通常的解聚条件下（与原始的黄烷键相反），由氧化产生的键不可裂解，因此自氧化后单宁结构会释放出特定的氧化残基。已经确定了分子间和分子内机制的氧化标志物。这些主要是二聚体和三聚体，或多或少被氧化，并且一些含有额外的羟基。此外，清楚地确定了构成这些二聚体和三聚体的亚基的性质（延伸与末端）。

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