They are made from oat groats that have been dehusked and steamed, before being rolled into flat flakes under heavy rollers and then stabilized by being lightly toasted.
The oat, like other cereals, has a hard, inedible outer husk that must be removed before the grain can be eaten.
[3] Since the bran layer, though nutritious, makes the grains tougher to chew and contains an enzyme that can cause the oats to go rancid, raw oat groats are often further steam-treated to soften them for a quicker cooking time and to denature the enzymes for a longer shelf life.
[3] Rolled oats can be eaten without further heating or cooking, if they are soaked for 1–6 hours in water-based liquid, such as water, milk, or plant-based dairy substitutes.
The required soaking duration depends on shape, size and pre-processing technique.