Physicochemical characterisation of casein micelles suspended in milk ultrafiltrate and enriched with different cations (Fe, Cu, Ca, Zn and Mg) was investigated. After addition of 2.5–8.0 mmol kg−1 of cations, associations of added cation, citrate, inorganic phosphate and calcium with casein micelles were observed. The order of association of cations with casein micelles was Fe3+ Zn2+ Ca2+ Cu2+ Mg2+. At the same time, the casein content increased in the casein micelles while the water content decreased. Changes in hydrophobicity and zeta potential of casein micelles were also determined while no variation in the average diameter was detected. In the presence of 8.0 mmol kg−1 of magnesium or ferric iron, heat stability (115 °C for 30 min) of casein micelles was decreased. From these results, a mechanism of cation association with casein micelles is proposed, highlighting the determinant role of ultrafiltrable citrate and inorganic phosphate. This mechanism is discussed in relation to modifications in physicochemical characteristics of casein micelles.

Ethics pervades every human society and almost every human life. People deliberate about what they should do on specifi c occasions, about what is worthwhile, about the kinds of lives they should aspire to lead. In subtle ways, their everyday actions presuppose habits of conduct, roles and institutions current in their societies, endorsed sometimes after serious refl ection, often accepted without much thought. With the exception of those affl icted with psychological disruptions that profoundly limit their cognitive capacities or that cut them off from their fellows, we are all embedded in the ethical project. Yet for ordinary people, and for phi los o phers too, the status of our ethical judgments and practices is hard to fathom. What exactly do we mean when we praise someone for a correct decision? How could an evaluation like that be grounded? Bertrand Russell famously described mathematics as a subject in which “. . . we never know what we are talking about, nor whether what we are saying is true.”1 The impressive ability of mathematicians to reach agreement on conclusions that endure fosters confi dence in their power to acquire knowledge, despite the mysteries swirling around the content and grounds of their judgments. By contrast, the per sis tence of ethical debate reinforces a sense of unease about the status of ethical practice, often leading those engaged in public controversies to shy away from “value judgments,” as if any hope of reaching consensus were absurd.