What happens to the temperature of products in open display cases when the air curtain is disrupted?

When the air curtain in open display cases is disrupted, the temperature of the products generally increases. The air curtain serves as a barrier that helps to minimize the exchange of air between the interior of the display case and the surrounding environment. This barrier is crucial for maintaining a stable temperature and preserving the integrity of the displayed products.

When the air curtain is compromised, hot air from the environment can directly enter the display case, leading to an increase in temperature. This rise can have detrimental effects on perishable items, potentially accelerating spoilage and reducing product quality. Hence, the correct answer highlights the direct relationship between the disruption of the air curtain and the resulting effects on temperature, underscoring the importance of this feature in maintaining the appropriate conditions for stored items.

The other answer choices suggest outcomes that would not realistically occur under typical conditions. For instance, maintaining stable temperatures or significant decreases would not align with the expected behavior of open display cases when external air disrupts their protective mechanisms.