Liquid Chromatography–Mass Spectrometry-Based Metabolomics for Understanding the Compositional Changes Induced by Oxidative or Anoxic Storage of Red Wines

The
aim of this work was to study the physicochemical changes of
eight red wines stored under conditions differing in O2 exposure and temperature and time under anoxia. The methods used
to analyze the wines included the measurement of volatile sulfur compounds,
color, tannin (T) polymerization, and liquid chromatography–mass
spectrometry untargeted metabolomic fingerprint. After 3 months, the
color of the oxidized samples evolved 4–5 times more intensively
than in wines stored under anoxia. The major metabolomic differences
between oxidative and anoxic conditions were linked to reactions of
acetaldehyde (favored in oxidative) and SO2 (favored in
anoxia). In the presence of oxygen, the C-4 carbocation of flavanols
delivered ethyl-linked tannin–anthocyanin (T–A) and
tannin–tannin (T–T) adducts, pyranoanthocyanins, and
sulfonated indoles, while under reduction, the C-4 carbocation delivered
direct linked T–A adducts, rearranged T–T adducts, and
sulfonated tannins. Some of these last reactions could be related
to the accumulation of reduced species, eventually ending with reductive
off-odors.

本研究旨在探究八种红葡萄酒在氧气暴露、温度及缺氧时间不同条件下的物理化学变化。分析葡萄酒的方法包括挥发性硫化合物、色泽、单宁（T）聚合以及液相色谱-质谱非靶向代谢组学指纹的测定。经过三个月的储存，氧化样酒的颜色变化强度是缺氧条件下储存葡萄酒的4至5倍。氧化与缺氧条件下的主要代谢组学差异与乙醛（在氧化条件下更易发生）和二氧化硫（在缺氧条件下更易发生）的反应有关。在有氧条件下，黄烷醇的C-4碳正离子会形成乙基连接的单宁-花青素（T-A）和单宁-单宁（T-T）加合物、吡喃花青素以及磺化吲哚，而在还原条件下，C-4碳正离子则形成直接连接的T-A加合物、重新排列的T-T加合物和磺化单宁。其中一些最后反应可能与还原物种的积累有关，最终导致还原型异味。