Data_Sheet_1_Impact of Increasing Levels of Oxygen Consumption on the Evolution of Color, Phenolic, and Volatile Compounds of Nebbiolo Wines.pdf

Since the end of the last century, many works have been carried out to verify the effect of controlled oxygen intake on the chemical and organoleptic characteristics of red wines. In spite of the large number of studies on this subject, oxygen remains a cutting-edge research topic in oenology. Oxygen consumption leads to complex and not univocal changes in wine composition, sometimes positive such as color stabilization, softening of mouthfeel, increase of aroma complexity. However, the variability of these effects, which depend both on the oxygenation conditions and the composition of the wine, require more efforts in this research field to effectively manage wine oxygen exposure. The present study is focused on the evolution of the chemical composition of four different Nebbiolo wines, each of them added with 4 different doses of oxygen (7, 14, 21, and 28 mg/L total intake) during the first month of storage. In this perspective, the evolution over time of wine color and polyphenols was studied. Acetaldehyde, glyceraldehyde and glyoxylic acid were quantified by HPLC. These compounds can play a role in wine aging creating condensed colored and stable products involving anthocyanins with or without tannins. Moreover, some volatile aldehydes correlated with oxidized olfactory notes, including methional and (E)-2-alkenals, have been quantified by GC-MS. Overall, during storage a decrease of color intensity, total and free anthocyanins and an increase in polymeric pigments (in particular the contribution to the red color of pigments not-bleachable by SO2 or dTAT%) and some minor aldehydes was observed. Nevertheless, the differences in color parameters between the samples with different doses of oxygen were modest. These evidences were in contrast with an evident and detectable increase of free acetaldehyde content at increasing doses of oxygen measured after 60 days of storage. The effect of oxygen on color and production of SO2 non-bleachable pigments during aging varies with wine composition, with Nebbiolo wines appearing not very reactive in this respect, probably due to their low content in anthocyanins and high content in tannins.

自上世纪末以来，已有多项研究旨在探究可控氧气摄入对红葡萄酒化学特性与感官品质的影响。尽管该领域已有大量研究，但氧气仍是酿酒学（oenology）中的前沿研究课题。氧气消耗会引发葡萄酒成分发生复杂且非单一的变化，其中部分变化具有积极作用，例如色泽稳定、口感柔化以及香气复杂度提升。然而，这些效应的变异性同时受充氧条件与葡萄酒本身成分的影响，因此该研究领域仍需投入更多工作，以实现对葡萄酒氧气暴露的有效管控。本研究聚焦于四款不同内比奥罗（Nebbiolo）葡萄酒的化学成分演化过程，在陈酿首月分别向其添加4种不同剂量的氧气（总摄入量分别为7、14、21及28 mg/L）。基于此，本研究对葡萄酒色泽与多酚类物质随时间的演化过程展开了探究。本研究通过高效液相色谱（HPLC）对乙醛、甘油醛及乙醛酸进行了定量分析；这类化合物可在葡萄酒陈酿过程中发挥作用，通过与含或不含单宁的花色素苷结合，形成缩合型有色稳定产物。此外，本研究还通过气相色谱-质谱联用仪（GC-MS）对与氧化型香气特征相关的部分挥发性醛类物质进行了定量，包括甲硫醛及(E)-2-alkenals。整体而言，陈酿过程中，葡萄酒的色泽强度、总花色素苷与游离花色素苷含量均出现下降，而聚合色素（尤其是二氧化硫不可漂白或dTAT%不褪色色素对红色调的贡献）以及部分微量醛类物质的含量则有所上升。尽管如此，不同氧气剂量处理组的色泽参数差异并不显著。这一结果与陈酿60天后测得的游离乙醛含量随氧气剂量增加而显著升高的现象相悖。陈酿过程中，氧气对色泽以及二氧化硫不可漂白色素生成的影响因葡萄酒成分而异；内比奥罗葡萄酒在该方面的反应性较低，这可能与其花色素苷含量较低、单宁含量较高有关。