Eat Right Practice Exam

Which food is most likely to deteriorate due to hydrolytic rancidity during storage at room temperature?

1. Fish oil

2. Soybean oil

3. Olive oil

4. Butter

The correct answer is: Butter

Hydrolytic rancidity primarily occurs when fats and oils break down as a result of reacting with water, often leading to the formation of free fatty acids. This process can be exacerbated by factors such as moisture, heat, and the presence of certain enzymes. Butter is particularly susceptible to hydrolytic rancidity because it contains both water and milk solids, which can facilitate this reaction. Being a dairy product, it has a higher moisture content than many oils, which makes it more prone to water-related degradation. When butter is stored at room temperature, the water and fat can interact more readily, leading to the breakdown of triglycerides into glycerol and free fatty acids, resulting in off-flavors and odors. On the other hand, oils like fish oil, soybean oil, and olive oil are primarily composed of fats with very little water content. This makes them less susceptible to hydrolytic rancidity at room temperature compared to butter. For example, fish oil and soybean oil are mainly emulsified and stored in containers that limit exposure to moisture, while olive oil typically possesses a high oleic acid content that gives it stability against rancidity. Thus, the composition and storage properties of butter make it the food most likely to deteriorate due to