What process involves mild surface dehydration?

The process that involves mild surface dehydration is drying. Drying is a method used to remove moisture from food or other materials, which helps in preserving them, preventing the growth of microorganisms, and extending shelf life. During drying, products lose their moisture content, which leads to a reduction in weight and volume, as well as changes in texture and flavor.

Fermentation is a biochemical process that converts sugars into acids, gases, or alcohol using microorganisms. This process does not primarily focus on dehydration but rather on the transformation of food through microbial activity.

Smoking is a preservation technique that uses smoke from burning or smoldering materials, usually wood. While it can impart flavor and help preserve food through chemical properties, it does not primarily involve dehydration.

Freezing involves lowering the temperature of food to below its freezing point, which preserves it by slowing down microbial growth and enzyme activity. However, it does not dehydrate the food; instead, it retains moisture in solid form.

Therefore, drying specifically focuses on removing moisture, making it the correct choice for the process that involves mild surface dehydration.