Oats that we eat as breakfast cereals are generally whole grains, and are also called groats. To make groats, the grain is roasted at a low temperature which inactivates the fat-splitting enzyme (else the grains would quickly turn rancid). This roasting also gives the grain greater integrity when cooking. The whole groats are then processed into various shapes, and all have nearly the same nutritional value. Most of the oats we buy are either steel-cut oats or rolled oats.
Steel cut oats are groats, which are cut into two to four pieces for faster cooking. Rolled oats are whole grains that are steamed to make them soft and then pressed between rollers to make them thin. The thinner the oats are rolled, the faster they rehydrate. Regular oats are about 0.8mm thick, “quick cooking” oats are 0.4mm thick and instant oats lesser than this.
Oats have several nutritional significance, that make them a highly recommended breakfast cereal. Oats contain a number of phenols that have anti-oxidant properties.
They are also rich in indigestible carbohydrates called beta-glucans, which absorb and store water. This beta-glucan property gives oatmeal its smooth, thick consistency. They also help lower our blood cholesterol levels. These, glucans are found mostly in the outer layers of the oat grain.
Oats do not have gluten-producing proteins, but are still avoided by people with gluten intolerance because many machines used to process oats are also used to process wheat and cross contamination cannot be necessarily avoided.
Trivia: A German immigrant, named Ferdinand Schumacher, in late 19th Century developed rolled oats. Henry Cromwell neatly packed the oats for retail packaging, with cooking instructions. The brand was called “Quaker oats.”