Which statement best describes what happens to fatty acids when oil begins to smoke during cooking?

• A. Trans to Cis
• B. Cis to Trans
• C. No change occurs
• D. Smoking does not relate to fatty acid geometry

Answer: (B)

When oil is heated to the point of smoking, the energy drives chemical changes in the unsaturated fatty acids. Cis double bonds can isomerize to the trans configuration under high heat, producing trans fats. The trans form is more linear and tends to be more stable under extreme temperatures, so some cis bonds flip to trans as the oil continues to smoke and break down. This is why high-heat cooking can lead to the formation of trans fatty acids. The other ideas don’t fit: reversing to cis would require a different process, no change wouldn’t reflect the chemical reactions underway, and smoking is indeed related to changes in fatty acid geometry during overheating.