Hayasaka Yoji, Black Cory A, Hack Jeremy, Smith Paul
The Australian Wine Research Institute, PO Box 197, Glen Osmond, SA 5064, Australia.
The Australian Wine Research Institute, PO Box 197, Glen Osmond, SA 5064, Australia.
Food Chem. 2017 Sep 1;230:99-107. doi: 10.1016/j.foodchem.2017.03.005. Epub 2017 Mar 6.
Reaction products of bisulfite and caftaric acid were found in wines containing sulfites as a preservative. Acidic compounds were separated from wine and analyzed by HPLC combined with DAD and QTOF mass spectrometer. HPLC chromatograms of the expected [M-H] ion and UV absorption revealed the presence of five possible reaction products (a-e). These compounds were isolated then characterized by NMR and confirmed to be the reaction products as follows; 5-sulfo-(E)-caftaric acid (a), 2-sulfo-(Z)-caftaric acid (b), 2-sulfo-(E)-caftaric acid (c), (E)-caftaric acid-4-O-sulfate (d) and (E)-caftaric acid-3-O-sulfate (e). UV spectra and high resolution product ion spectra of the five compounds also supported their identity. The reaction products were confirmed to be commonly present in commercial wines across four vintages and two varieties. Their concentration was found to be as much as that of 2-S-glutathionyl caftaric acid, suggesting that bisulfite consistently competes as a nucleophile with glutathione for the o-quinone of caftaric acid.
在含有亚硫酸盐作为防腐剂的葡萄酒中发现了亚硫酸氢盐与咖啡酸的反应产物。从葡萄酒中分离出酸性化合物，并通过高效液相色谱（HPLC）结合二极管阵列检测器（DAD）和四极杆飞行时间质谱仪（QTOF）进行分析。预期的[M-H]离子的HPLC色谱图和紫外吸收显示存在五种可能的反应产物（a - e）。然后分离这些化合物，通过核磁共振（NMR）对其进行表征，并确认它们是如下反应产物：5-磺基-(E)-咖啡酸（a）、2-磺基-(Z)-咖啡酸（b）、2-磺基-(E)-咖啡酸（c）、(E)-咖啡酸-4-O-硫酸盐（d）和(E)-咖啡酸-3-O-硫酸盐（e）。这五种化合物的紫外光谱和高分辨率产物离子光谱也支持了它们的结构鉴定。已证实这些反应产物在四个年份和两个品种的商业葡萄酒中普遍存在。发现它们的浓度与2-S-谷胱甘肽基咖啡酸的浓度相当，这表明亚硫酸氢盐作为亲核试剂一直与谷胱甘肽竞争咖啡酸的邻醌。
