Which compound is primarily responsible for off flavors in oils?

Acrolein is primarily responsible for off flavors in oils due to its volatile nature and distinctive pungent aroma. When oils are heated beyond their smoke point or undergo oxidation, acrolein, a product formed from the degradation of glycerol during the heating process, can impart an unpleasant taste and smell. This compound is particularly notorious because it can develop at relatively low temperatures and is a significant indicator of oil quality deterioration.

In contrast, acrylamide, glycerol, and fatty acids do not play the same role in contributing to off flavors in oils. While acrylamide is a compound formed from certain chemical reactions during cooking, it is not typically associated with oils' off flavors. Glycerol serves as a backbone for triglycerides and does not directly contribute to flavor issues. Fatty acids can influence flavor to some degree, but they do not result in the sharp, undesirable flavors associated with acrolein. Thus, acrolein is the clear culprit for off flavors in oils, making it the correct choice.