Nikolantonaki Maria, Magiatis Prokopios, Waterhouse Andrew L
Department of Viticulture and Enology, University of California, Davis, CA 95616, United States.
Department of Pharmacognosy and Natural Products Chemistry, Faculty of Pharmacy, University of Athens, Panepistimioupolis Zografou 15 771, Athens, Greece.
Food Chem. 2014 Nov 15;163:61-7. doi: 10.1016/j.foodchem.2014.04.079. Epub 2014 Apr 30.
Quinones are central intermediates in wine oxidation that can degrade the quality of wine by reactions with varietal thiols, such as 3-sulfanylhexanol, decreasing desirable aroma. Protection by wine preservatives (sulphur dioxide, glutathione, ascorbic acid and model tannin, phloroglucinol) was assessed by competitive sacrificial reactions with 4-methyl-1,2-benzoquinone, quantifying products and ratios by HPLC-UV-MS. Regioselectivity was assessed by product isolation and identification by NMR spectroscopy. Nucleophilic addition reactions compete with two electron reduction of quinones by sulphur dioxide or ascorbic acid, and both routes serve as effective quenching pathways, but minor secondary products from coupled redox reactions between the products and reactants are also observed. The wine preservatives were all highly reactive and thus all very protective against 3-sulfanylhexanol loss to the quinone, but showed only additive antioxidant effects. Confirmation of these reaction rates and pathways in wine is needed to assess the actual protective action of each tested preservative.
醌类是葡萄酒氧化过程中的关键中间体，可通过与品种硫醇（如3-巯基己醇）反应降低葡萄酒品质，减少诱人的香气。通过与4-甲基-1,2-苯醌的竞争性牺牲反应评估葡萄酒防腐剂（二氧化硫、谷胱甘肽、抗坏血酸和模型单宁间苯三酚）的保护作用，通过高效液相色谱-紫外-质谱联用法定量产物和比例。通过核磁共振光谱法对产物进行分离和鉴定来评估区域选择性。亲核加成反应与二氧化硫或抗坏血酸对醌类的双电子还原反应相互竞争，这两条途径都是有效的淬灭途径，但也观察到产物与反应物之间耦合氧化还原反应产生的少量副产物。葡萄酒防腐剂都具有高反应活性，因此对醌类导致的3-巯基己醇损失都有很强的保护作用，但仅表现出相加的抗氧化效果。需要在葡萄酒中确认这些反应速率和途径，以评估每种测试防腐剂的实际保护作用。
