What flavor can develop in milk due to the dissolution of copper or white metal?

The development of an oxidized flavor in milk is associated with the dissolution of copper or white metal. When metal ions enter the milk, they can catalyze the oxidation of the milk's fat components and other substances. This oxidation process leads to the formation of off-flavors often described as cardboard-like or rancid, characteristic of an oxidized flavor.

Copper and certain other metals are known to be particularly reactive with the components of milk, facilitating chemical changes that produce these undesirable flavors. It's important to use equipment that is composed of appropriate materials, like stainless steel, to minimize the risk of metal contamination and the resulting flavor changes.

In contrast, the other options like acidic, sweet, or salty flavors do not arise from the presence of copper or white metal in milk. An acidic flavor, for instance, is usually a result of spoilage or fermentation, while sweet or salty flavors might stem from different factors such as additives or the natural composition of various milk products.