What is oatmeal?
All types of oatmeal are derived from the seeds of the oat plant. After harvesting the oats, and de-hulling them to form oat groats, the groats are processed many different ways to produce various end products.
Cutting, milling, flaking, and rolling processes are used to make the forms of oatmeal we are most familiar with:
Steel cut oats are simply oat groats that have been cut 2-3 times in order to make them easier to cook and eat than whole oat groats. Also known as Irish oats, steel cut oats are known for their chewy texture and distinctive nutty flavor. This type of oat is eaten primarily as a cereal.
Rolled oats are oat groats that have been steamed and rolled into a flattened ovular shape. This makes them much quicker to cook for cereal, and easier to include in other recipes such as cookies and breads. Rolled oats are probably the variety people are most familiar with. Quaker Oats sells these as Old-Fashioned oats.
Instant oats are rolled oats that have been further processed to make the cooking process even faster. These will have a creamy texture and flavor.
Oat bran and oat flour are the two byproducts of a milling process that separates these two components of the whole oat groat. These types of oatmeal are typically included as ingredients in various recipes rather than being consumed in its pure form.