Back in the 1990s, McDonald’s method for making french fries involved frying them in beef tallow, but it has come a long way since then — a process that the fast food chain has been pretty transparent about. However, the same can’t be said for their hash browns, and many don’t even know what potato variety is used to make them.

When McDonald’s first opened, they only used one kind of potato — the russet, specifically the Russet Burbank. Over the years, they’ve incorporated more varieties of russet — first the Ranger, Umatilla, and Shepody, and later the Clearwater Russet and the Blazer Russet as well.

Besides potatoes, McDonald’s hash browns also contain oils, a "wheat and milk derivative" for beef flavor, salt, corn flour, dehydrated potatoes, dextrose, sodium acid pyrophosphate, and black pepper extract, per Fooducate. So, while McDonald’s hash browns aren’t the healthiest thing on the menu, they aren’t exactly a powerhouse of ingredients and fillers either.