Which of the following is not an acceptable technique for cooling food?

Using a freezer to cool food is not considered an acceptable technique for safely cooling down hot food. When food temperature is rapidly lowered in a freezer, it risks entering the "danger zone" (40°F to 140°F) for an extended period if the food is not cooled properly before placing it in the freezer. This can promote bacterial growth, leading to foodborne illnesses.

In contrast, the other methods mentioned are preferred because they effectively reduce the temperature of the food while minimizing the risk of bacterial growth. For example, adding ice as an ingredient in a cooked dish immediately cools the food, and using an ice paddle to stir hot liquids allows for efficient heat transfer, effectively reducing temperature. Similarly, shallow pans in a blast chiller increase surface area, allowing for quicker cooling. Each of these techniques promotes safe practices in food cooling, which is essential for maintaining food safety.