The part of the potato just below the outer skin is the cortex. Just below the cortex is the vascular system. People claim just under the potato skin is its most nutritious part. Yet, the average consumer discards the skin and part of the cortex when he or she prepares the starchy tubers. To counter this, some choose not to peel their potatoes, but to wash and eat the entire potato.
Anatomy of a Potato
A naive viewpoint would assume the potato is simply a brown skin covering an ellipsoid of uniform, white starchy material. The potato has a number of distinguishable anatomical features, in fact.
First there is the skin of a potato. It is called the periderm. Moving into the interior, we next encounter the cortex. Next is the vascular ring, appearing in cross-section as a ring of dots.
From there extends the perimedullar zone. We might think of it as the bulk of the potato. Through it runs the medulla, usually nearly indistinguishable in the healthy potato. This part of the potato runs from the one end to the other, from the stolon or stem end nearly to the apical or rose end of the tuber.
Where’s the Nutrition?
A popular saying is that most of the nutrition is to be found in the skin of the potato. While that is not absolutely true, neither is it completely without basis.1 Much of the nutrition of a potato is to be found in the skin and that which lies just below the skin. Especially is this so when the relatively light weight of the skin is compared to the much greater weight of the interior flesh.
However, there is another important point to be made. If a potato is boiled or baked, a fair percentage of its nutrition either passes into the water to be discarded, or it is thermally destroyed by the cooking process. Nutritionally, it is better to steam or microwave a potato.
Nutrient Distribution: Why There?
The distribution of some of the minerals in the entire potato may be dictated by the ability to travel in the phloem of a potato. Other minerals may directly absorb through the tuber skin. And of course, the needs of the plant will dictate much of the chemistry one can expect to find present in any particular portion of a potato. The driving transport forces, however, have not been clearly delineated.
1 In particular, the highest concentration of many minerals in a potato tuber are found in greatest quantity, usually in the skin and in the stolon end of a potato, though a few existed in greater quantity at the interior and the bud end of a potato.
- Penn State University: Potato Biology and Biotechnology – Advances and Perspectives
- Electronic Journal of Polish Agricultural Universities: Method of Acoustic Emission in the Studying of Cracking Processes in Plant Tissues
- The Idaho Potato Commission: Ask Dr. Potato – Should I Be Eating the Skin of the Potato?
- Colorado State University: Potato Nutrition Handbook 2015: Potatoes – Goodness Unearthed
- NCBI: NLM: Annals of Botany 2011 Apr; 107(4): 681-691. The three-dimensional distribution of minerals in potato tubers, Subramanian, et. al.