National and Kapodistrian University of Athens, Department of Chemistry, Laboratory of Environmental Chemistry, Panepistimiopolis, Zografou, 15784 Athens, Greece.
University of West Attica, Department of Food Science and Technology, Laboratory of Chemistry, Analysis & Design of Food Processes, Agiou Spiridonos 28, Egaleo 122 43, Greece.
Molecules. 2020 Feb 15;25(4):861. doi: 10.3390/molecules25040861.
Complex formation is among the mechanisms affecting metal bioaccessibility. Hence, the quantification of organic metal complexation in food items is of interest. Organic ligands in solutions of environmental and/or food origin function as buffering agents against small changes in dissolved metal concentrations, being able to maintain free metal ion concentrations below the toxicity threshold. Organic matter in vinegars consists of bioactive compounds, such as polyphenols, Maillard reaction endproducts, etc., capable of complexing metal ions. Furthermore, transition metal ions are considered as micronutrients essential for living organisms exerting a crucial role in metabolic processes. In this study, differential pulse anodic stripping voltammetry (DPASV), a sensitive electrochemical technique considered to be a powerful tool for the study of metal speciation, was applied for the first time in vinegar samples. The concentrations of Cu complexing ligands () in 43 vinegars retailed in Greece varied between 0.05 and 52 μM, with the highest median concentration determined in balsamic vinegars (14 μM), compared to that of common vinegars (0.86 μM). In 21% of the vinegar samples examined, values were exceeded by the corresponding total Cu concentrations, indicating the presence of free Cu ion and/or bound within labile inorganic/organic complexes. Red grape balsamic vinegars exhibited the highest density of Cu ligands per mass unit of organic matter compared to other foodstuffs such as herbal infusions, coffee brews, and beers. Among the 16 metals determined in vinegars, Pb is of particular importance from a toxicological point of view, whereas further investigation is required regarding potential Rb biomagnification.
配合物形成是影响金属生物可给性的机制之一。因此，对食品中有机金属配合物的定量分析很有意义。环境和/或食物来源的溶液中的有机配体作为缓冲剂，可以抵抗溶解金属浓度的微小变化，能够将游离金属离子浓度维持在毒性阈值以下。醋中的有机物由生物活性化合物组成，如多酚、美拉德反应终产物等，它们能够与金属离子配合。此外，过渡金属离子被认为是生物体所必需的微量元素，在代谢过程中发挥着关键作用。在这项研究中，首次将差分脉冲阳极溶出伏安法（DPASV）应用于醋样品，这是一种灵敏的电化学技术，被认为是研究金属形态的有力工具。在希腊零售的 43 种醋中，Cu 配合物配体（）的浓度在 0.05 至 52 μM 之间变化，香醋中的浓度最高（14 μM），而普通醋中的浓度为 0.86 μM。在所检查的 21%的醋样品中，值超过了相应的总 Cu 浓度，表明存在游离的 Cu 离子和/或与不稳定的无机/有机配合物结合。与其他食品（如草药浸剂、咖啡酿造物和啤酒）相比，红葡萄香醋每单位有机物质的 Cu 配体密度最高。在所测定的 16 种金属中，Pb 从毒理学角度来看尤为重要，而对于潜在的 Rb 生物放大作用还需要进一步研究。
