Certified Cheese Professional Practice Exam

Oxidation of unsaturated phospholipids in milk produces off-flavors described as which of the following?

1. Fruity, nutty, or earthy

2. Painty, fishy, or metallic

3. Sweet, sour, or tangy

4. Creamy, buttery, or cheesy

The correct answer is: Painty, fishy, or metallic

The oxidation of unsaturated phospholipids in milk primarily leads to the development of off-flavors that are specifically characterized by descriptors such as "painty," "fishy," or "metallic." These flavors are a result of various oxidative processes that affect the structure of lipids, leading to the formation of volatile compounds which contribute to these undesirable sensory attributes. When unsaturated lipids undergo oxidation, they break down and can create byproducts like aldehydes and ketones, which have the potential to impart unpleasant tastes and odors. The "fishy" notes are particularly noticeable due to specific compounds that may have similar characteristics to those found in oxidized fish oils. Similarly, some metallic notes can arise from the interaction of oxidation products with metal ions present in the environment. In contrast, the other descriptors listed in the other choices do not accurately represent the flavors associated with lipid oxidation. Fruity, nutty, or earthy flavors relate more to the natural complexities found in certain cheeses or ripened dairy products, rather than being indicative of oxidative degradation. Sweet, sour, or tangy is often associated with fermentation processes rather than lipid oxidation. Lastly, creamy, buttery, or cheesy flavors typically result from the inherent qualities of the milk fat rather than