Kreitman Gal Y, Danilewicz John C, Jeffery David W, Elias Ryan J
Department of Food Science, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.
44 Sandwich Road, Ash, Canterbury, Kent CT3 2AF, United Kingdom.
J Agric Food Chem. 2016 May 25;64(20):4095-104. doi: 10.1021/acs.jafc.6b00641. Epub 2016 May 11.
Sulfidic off-odors as a result of hydrogen sulfide (H2S) and low-molecular-weight thiols are commonly encountered in wine production. These odors are usually removed by the process of Cu(II) fining, a process that remains poorly understood. The present study aims to elucidate the underlying mechanisms by which Cu(II) interacts with H2S and thiol compounds (RSH) under wine-like conditions. Copper complex formation was monitored along with H2S, thiol, oxygen, and acetaldehyde concentrations after the addition of Cu(II) (50 or 100 μM) to air-saturated model wine solutions containing H2S, cysteine, 6-sulfanylhexan-1-ol, or 3-sulfanylhexan-1-ol (300 μM each). The presence of H2S and thiols in excess to Cu(II) led to the rapid formation of ∼1.4:1 H2S/Cu and ∼2:1 thiol/Cu complexes, resulting in the oxidation of H2S and thiols and reduction of Cu(II) to Cu(I), which reacted with oxygen. H2S was observed to initially oxidize rather than form insoluble copper sulfide. The proposed reaction mechanisms provide insight into the extent to which H2S can be selectively removed in the presence of thiols in wine.
在葡萄酒生产过程中，由于硫化氢（H₂S）和低分子量硫醇而产生的硫化异味很常见。这些异味通常通过铜（II）澄清工艺去除，但该过程仍未得到充分理解。本研究旨在阐明在类似葡萄酒的条件下，铜（II）与H₂S和硫醇化合物（RSH）相互作用的潜在机制。在向含有H₂S、半胱氨酸、6-巯基己醇或3-巯基己醇（各300μM）的空气饱和模型葡萄酒溶液中添加铜（II）（50或100μM）后，监测铜络合物的形成以及H₂S、硫醇、氧气和乙醛的浓度。H₂S和硫醇相对于铜（II）过量存在会导致快速形成约1.4:1的H₂S/Cu和约2:1的硫醇/Cu络合物，从而导致H₂S和硫醇被氧化，铜（II）还原为铜（I），后者与氧气反应。观察到H₂S最初是被氧化而不是形成不溶性硫化铜。所提出的反应机制有助于深入了解在葡萄酒中存在硫醇的情况下，H₂S能够被选择性去除的程度。
