Noyhouzer Tomer, Kohen Ron, Mandler Daniel
Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel.
Department of Pharmaceutics, School of Pharmacy, The Hebrew University of Jerusalem, Jerusalem, 91120, Israel.
Anal Methods. 2009 Nov 1;1(2):93-99. doi: 10.1039/b9ay00078j.
Milk is one of the most fundamental ingredients in our diet. It is a complex biological fluid, which contains numerous substances, ranging from metal ions to enzymes. There is a constant search for an improved way of monitoring its quality and freshness. These are highly affected by the redox state of milk, which is governed by different species. In this study, we investigated the redox state and capacity of milk. Specifically, milk was potentiometrically titrated using different redox mediators, which enabled facilitation of electron transfer between different oxidizable species and the electrode. We found that the iodine/iodide redox couple was superior for measuring the redox capacity of milk. These measurements revealed that milk is not a well-poised system due to the presence of at least two different oxidizable species, one of which is hydrophobic while the other is hydrophilic and therefore could be separated by phase separation of milk.
牛奶是我们饮食中最基本的成分之一。它是一种复杂的生物流体，含有从金属离子到酶等多种物质。人们一直在不断探索改进的方法来监测其质量和新鲜度。这些质量和新鲜度受到牛奶氧化还原状态的极大影响，而牛奶的氧化还原状态由不同的物质决定。在本研究中，我们调查了牛奶的氧化还原状态和能力。具体而言，使用不同的氧化还原介质对牛奶进行电位滴定，这有助于促进不同可氧化物质与电极之间的电子转移。我们发现碘/碘化物氧化还原对在测量牛奶的氧化还原能力方面表现更优。这些测量结果表明，由于至少存在两种不同的可氧化物质，牛奶不是一个平衡良好的体系，其中一种是疏水性的，另一种是亲水性的，因此可以通过牛奶的相分离将它们分开。
