Rolled oats

Rolled oats are a type of lightly processed whole-grain food. 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.

Thick-rolled oats usually remain unbroken during processing, while thin-rolled oats often become fragmented. Rolled whole oats, without further processing, can be cooked into a porridge and eaten as old-fashioned oats or Scottish oats; when the oats are rolled thinner and steam-cooked more in the factory, they will later absorb water much more easily and cook faster into a porridge, and when processed this way are sometimes called "quick" or "instant" oats.

Rolled oats are most often the main ingredient in granola and muesli. They can be further processed into a coarse powder, which breaks down to nearly a liquid consistency when boiled. Cooked oatmeal powder is often used as baby food.

Process
The oat, like other cereals, has a hard, inedible outer husk that must be removed before the grain can be eaten. After the outer husk (or chaff) has been removed from the still bran-covered oat grains, the remainder is called oat groats. 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.

Steel-cut or pinhead oats
Steel-cut oats (sometimes called "pinhead oats", especially if cut small) are oat groats that have been chopped by a sharp-bladed machine before any steaming, and thus retain bits of the bran layer.

Preparation
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.

Whole oat groats can be cooked as a breakfast cereal in the same general way as the various forms of oatmeal, rolled oats, and pinhead oats; they simply take longer to cook. Rolled oats are used in granola, muesli, oatcakes, and flapjacks (the style of "flapjack" that is like a granola bar, not a pancake).

Nutrients
Whole oats (uncooked) are 68% carbohydrates, 6% fat, and 13% protein (table). In a 100-gram reference amount, whole oats supply 379 calories and contain high amounts (20% or more the Daily Value, DV) of the B vitamins – thiamine and pantothenic acid (40% and 22% DV, respectively) – and several dietary minerals, especially manganese (173% DV) and phosphorus (59% DV). As a rich source of dietary fiber (10 grams per 100 gram serving), whole oats supply beta-glucan (4 grams per 100 gram serving; table), a soluble fiber with cholesterol-lowering effects.