Rolled and steel cut oats are two forms of oats which can be distinguished on the basis of the degree to which they are processed. Even if these two forms are processed differently, they both fall under the category of whole grains. There are not many differences between these forms with respect to nutrition obtained from them. The major differences being associated with processing are mentioned below.
Rolled oat groats are processed in three steps, i.e. they are rolled, steamed, and then toasted, after removing their outer husk. These grains are generally sold as oatmeal. The steel-cut oats, instead of being rolled and steamed, are chopped into 2-3 pieces. The different names given to these oats include Irish oats and pinhead oats. Processing time for these oats is much lesser than that of the rolled ones.
The difference between these two oat varieties, as stated above, is the way in which they are processed. Steel cut oats, unlike the rolled ones, are not rolled, steamed, or toasted. They are just chopped. A bit of the bran layer is retained on these oats. There are advantages as well as disadvantages of having this layer over grains.
The advantage is that the micronutrients present in bran are not lost. On the flip-side, it becomes difficult to chew the grains. Rolled oats may or may not possess the bran layer. In most cases, this layer is removed from the grain. Given below are some more differences.
Rolled oats are in the form of flat, lengthwise flakes. Steel cut oats look like they are cut into two halves. Their appearance is similar to that of wild rice in its cooked form.
The texture of steel cut oats is a bit coarse, and hence the effort which goes into chewing them is more than that of rolled oats. The opinion about which variety has a better texture differs from person to person.
Steel cut oats have a nutty flavor. Rolled oats do not have such kind of a flavor.
Rolled oats occupy more space/volume than steel cut oats. This is because the latter is denser than the former. This difference in density results in the difference in volume. Half a cup of rolled oats is considered to be equivalent to a quarter cup of steel cut ones. Also, water absorbed by steel cut oats is greater.
Steel cut oats score over rolled oats in terms of nutrition, due to lesser processing. The process of steaming of rolled oats is responsible for loss of micronutrients. The amount of vitamins and minerals present in steel cut oats is therefore greater. The steaming process also increases the time required for cooking the grains.
Both options are considered to be good from the point of nutrition. Cereal in the form of steel cut oats however, contain more fibers, and is therefore useful in keeping various health problems at bay.