The absence of which metals in milk is crucial to prevent oxidation and undesirable flavors?

The absence of iron and copper in milk is crucial to prevent oxidation and undesirable flavors because both metals act as catalysts in oxidation reactions. When present in milk, even in trace amounts, iron and copper can initiate oxidative processes that lead to the deterioration of milk quality, resulting in off-flavors and rancidity.

Milk is particularly susceptible to these oxidative reactions because it contains unsaturated fats and various other compounds that can be negatively impacted. For example, when milk is exposed to light, iron can interact with certain proteins and fats, further enhancing the development of rancid flavors. By ensuring that iron and copper levels are kept low, the overall stability of the milk is maintained, preserving its taste and nutritional integrity.