Question

Cake mixes and other packaged foods that require cooking often contain special directions for use at high elevations. Typically these directions indicate that the food should be cooked longer above \(5000 \mathrm{ft}\). Explain why it takes longer to cook something at higher elevations.

Short answer

At higher elevations, atmospheric pressure decreases, causing the boiling point of water to decrease as well. This lower boiling point affects heat transfer through water during cooking processes like boiling, steaming, or simmering, resulting in foods taking longer to reach their desired internal temperature or become tenderized. Therefore, packaged food directions suggest longer cooking times at high elevations (above 5000 feet) to ensure that the food is cooked thoroughly and safely.

Step-by-step solution

Understand the relationship between atmospheric pressure and elevation

As elevation increases, atmospheric pressure decreases due to the decreasing weight of the air column above the given elevation. This reduced pressure has a direct effect on the boiling point of water.

Learn the effect of atmospheric pressure on boiling point of water

At sea-level, water boils at 100°C (212°F) because the atmospheric pressure is sufficient to keep water molecules contained in their liquid state until they gain enough energy to vaporize. However, at higher elevations where atmospheric pressure is lower, water molecules can escape into the vapor phase more quickly, requiring less energy. As a result, the boiling point of water decreases with increasing elevation.

Discover the implications of a lower boiling point on cooking time

Since cooking often involves the transfer of heat through water, a lower boiling point of water at high elevations means that water will boil at a lower temperature compared to sea-level. Cooking processes like boiling, steaming, or simmering rely on this heat transfer to break down the connective tissues in meat, cook vegetables to a tender state, and kill bacteria. Due to the decreased temperature at which water boils at high elevations, foods will take longer to reach their desired internal temperature or become tenderized.

Apply this understanding to packaged food directions

Packaged food directions for use at high elevations (above 5000 feet) often require longer cooking times to ensure that the food is cooked thoroughly since it can take longer at the lower boiling point to achieve the necessary internal temperature. These instructions are designed to adjust for the difference in boiling point and ensure the food is cooked correctly and safely. To conclude, it takes longer to cook something at higher elevations, primarily due to the decrease in atmospheric pressure and the resulting lower boiling point of water. This lower boiling point affects heat transfer and causes foods to require more time to cook thoroughly.