Types and designations of raw oats can be confusing, as some terms refer to the origins of the cereal grain, some to the way the grains were processed, and some to the way you’re meant to cook them.
You can generally find whole oats only in health food stores, bulk food stores, or on the Internet. This type takes the longest to cook, but is richest in fiber and nutrition, and fans (like me!) enjoy their nutty flavor and toothsome texture.
Process your oats one step further by cutting them into pieces, and you’ve got steel-cut oats, which are also commonly called pinhead oats, Irish oatmeal, or porridge oats. Some might call this variety Scottish oats, but I beg to differ. In England, Scandinavia, and the United States, this type is considered a specialty item and you’ll have to look for them in upscale markets, import grocers, or health food stores.
Scottish oats contain whole groats, like the steel cut, but are ground into uneven pieces rather than cut with a blade. This results in crushed bits, yielding a bowl of porridge that’s creamier and less grainy than Irish oatmeal.
Rolled oats, sometimes called old-fashioned oats, are what the English, Americans, and Scandinavians consider basic oatmeal. To produce this style of cereal grain, the groats are steamed and then rolled into flakes. The greater surface area on the flakes helps them cook longer. Rolled oats make for a very creamy bowl of hot cereal that’s less chewy and blander than the less processed types.
If you pressed rolled oats even flatter and steam them even longer, you’ll wind up with quick-cooking oats. Even flatter and even longer? Instant oatmeal. These final two have a less firm texture that some describe as watery. It’s an advantage for some oat lovers, and a drawback for others.
For the most part, people like their bowl of hot oatmeal the way they like it, which is generally the way their mum served it when they were children. But for cooking, different styles offer different perks, so it’s great to be familiar with the whole gamut.