How Oats Are Processed

Oat grains and bowl of rolled oats
Learn the difference between rolled and steel cut oats.

As the advantages of eating oatmeal become better understood, you may wonder how oats are processed and whether or not it has an effect on the health benefits. How are steel cut, rolled oats and quick oats different?

Oat Processing Begins With Similarities

The three basic types of oatmeal all begin with the same basic process. Raw oats are cleaned to remove other grains or things like rocks or weeds that may have been mixed into the oats. The grains are passed through various sized screens to strain out the debris.

The next step is to remove the outer hull from the inner kernel, or groat. A machine tumbles the raw oats, usually throwing them into a rubber ring, to knock off the hull. The mixture then moves into an aspirator, which blows air through and across the grain, blowing off the loose hulls. A final machine scours the remaining grouts to clean them.

The final two steps are conditioning and roasting. Conditioning is simply the process of increasing the moisture content in the groats so they can be roasted without burning. Roasting is done using dry heat and gives oats their familiar nutty flavor while also reducing the moisture level back to a level that allows the groats to be stored without molding or souring.

Does How Oats Are Processed Make a Difference?

The differences in processing take place after this initial processing. Steel cut, rolled oats and quick oats take different routes to get to the table.

Steel Cut

Steel cut oats go by several different names, including Irish oats, Scotch oats or coarse-cut oats. The toasted groats are coarsely chopped into small pieces, roughly the size of a sesame seed. These oats are very similar to stone-ground oats, except that as the name implies, stone-ground oats are ground rather than chopped. Stone-ground oats are usually slightly smaller than steel cut. Both varieties are high in B vitamins as well as containing protein, fiber and other nutrients, including an essential fatty acid called gamma linolenic acid (GLA). Steel cut oats also have a chewy, nutty texture and flavor.

Steel cut oats require the longest cooking time of the three types. You need to bring the water to a boil in a saucepan and stir in the oats, then reduce the heat and cover to simmer for about 30 minutes. You can reduce cooking time, however, by soaking the oats overnight. Steel cut oats can also be cooked overnight in a slow cooker, or even microwaved.

Rolled Oats

Rolled oats may also be labeled old-fashioned oatmeal or flaked oats. To create rolled oats, the groats are steamed, pressed through rollers to flatten, then steamed again and toasted. This processing creates a faster cooking oatmeal that can be completed, start to finish, in as little as 15 minutes, but they have a gummier, less chewy texture and less of the nutty flavor of steel cut oats. Rolled oats contain the same vitamins and other nutrients, but in slightly smaller amounts because the steaming process removes some of the nutrients. Rolled oats also have less dietary fiber.

Quick Oats

Quick oats and instant oatmeal are made in a similar fashion as rolled oats, but the groats are chopped or cracked into smaller pieces before being steamed and pressed. Because the pieces are so small, they cook very quickly when warm water is added, but the texture is very gummy, which some people find unpleasant. Like rolled oats, the additional processing for quick oats removes some of the nutrients when compared to steel cut oats.

Unless you are eating instant oatmeal, which can contain added sugar or artificial flavorings, how oats are processed will not have a major impact on the nutritional value. Steel cut oats come out slightly higher in most nutrients, especially fiber, but the longer cooking time required may make it inconvenient for busy households. With what is known about the health benefits of eating oatmeal, if the convenience of rolled or quick oats makes it easier to eat oatmeal more often, it may be worth the trade-off.

How Oats Are Processed