Final answer:
The reason to saturate a polyunsaturated fatty acid is to prevent oxidation and, when partially hydrogenated, to increase fluidity to make spreadable products. Saturation makes fats more solid at room temperature and increases their shelf-life by stabilizing the molecular structure against oxidative processes.
Step-by-step explanation:
The process of saturating a polyunsaturated fatty acid serves specific purposes. Saturation refers to the addition of hydrogen atoms to the carbon chain, typically to reduce the number of carbon-carbon double bonds. The rationale for this process is not to increase its fluidity, as saturation typically results in a solid or semi-solid state at room temperature. Instead, one of the main reasons to saturate polyunsaturated fatty acids is C. To prevent oxidation. Oxidation of unsaturated fats can lead to rancidity and the loss of quality and nutritional value. By saturating these fats, you increase their stability, making the oils more shelf-stable and less prone to spoiling.
Polyunsaturated fats, which have multiple double bonds in their structure, are typically liquid at room temperature due to the kinks in their carbon chains caused by these double bonds. These kinks prevent the molecules from packing tightly together. The process of hydrogenation straightens out these kinks by converting double bonds into single bonds, increasing the melting point and thus, the fats become more solid or semi-solid. This is why partially hydrogenated oils can be spreadable, like margarine, and have a longer shelf-life compared to their non-hydrogenated counterparts.
In conclusion, the correct answer to the student's multiple-choice question is D. Both A and C, as saturation can decrease oxidation and, when partially hydrogenated, increase fluidity to make a spreadable product at room temperature.