What describes the skin of fries that are slightly underdone?

The skin of fries that are slightly underdone is described as shiny and tough. When fries are undercooked, the moisture content is still retained in the potato, which prevents them from achieving the desired crispiness. The shiny appearance comes from the surface moisture and the lack of sufficient frying time to create a dry, crispy exterior. The toughness refers to the texture of the fry skin, which has not had the opportunity to become light and airy during the cooking process.

As a result, it is essential to ensure that fries are cooked for the appropriate duration to allow the sugars and starches to caramelize properly, leading to that ideal crispiness and golden-brown color.