Although generally safe to eat, frozen carrots often have a mushy or watery texture after they thaw. Freezer burn can also damage them if the carrots aren't stored in an airtight container.
Carrots, like all vegetables, consist of millions of cells that are contained and supported by cell walls. When the carrots freeze, the water inside the cells expands, bursting the rigid cell walls. Once these walls break down, the vegetables become soggy. They often retain their taste, however, and work well in cooked presentations or soups.
Freezer burn affects frozen food exposed to the air outside its packaging. Over time, the cold, dry air absorbs moisture from the food, leaving it with a leathery texture and stale taste.