Science of potato

Potatoes are known all over the world. They differ in sizes, shapes, and tastes. There are over 4000 different varieties of potatoes categorized into a few main groups. What do we owe to their popularity, and what are the benefits of eating them? Let’s take a closer look at that field.

Image credit: Agnieszka Pregowska

The inconspicuous vegetable that changed the world’s fate is nothing else but a potato (Latin name: Solanum tuberosum L) from a nightshade family. Potatoes came to Europe due to sea expeditions to America, where they were grown by native Americans. For these ethnic groups, potatoes were not just food; they found various uses for this vegetable, like medical use. Most possibly introducing potatoes to Europe ended famine and fueled the rise of the west empires, which eventually asserted domination over most of the world between 1750 and 1950 [1]. In fact, they have a much longer history. Archeological studies confirm that potatoes were cultivated about 400 BC, while detailed studies of the starch from the potatoes dated it for even 7000 years before its presence. They were the first to be cultivated by Inca Indians in Peru and Chile. Currently, potatoes produce more food per unit of water than any other major crop, and so they are the third most important crop in terms of consumption.

There are many varieties of potatoes in the world that have been divided into groups: russet (with a soft and fluffy interior), red (their skin remains plump when cooked), yellow (combination of a creamy texture with a buttery flavor), white (with a nutty aftertaste), purple (earthy flavor), fingerling (nutty-buttery flavor), russet (fluffy centre with thick coat) and petite (their attribute is achieved large sizes).

Image credit: Agnieszka Pregowska

Chemistry of potatoes

At first glance, a potato is a starch and water, but there are much more ingredients. It also contains amino acids, proteins, intermediate hydrolysis products of proteins, and some non-starch carbohydrates like cellulose [2]. It is also made of various enzymes and organic acids. Potatoes are not as rich in vitamins as other vegetables, but they are especially rich in potassium, which exists as potassium phosphate. Single potato has much more potassium than banana which is well known for containing enormous amounts of this element. Overall, potato is relatively low on calories and so not that bad for diets; 225 grams of this vegetable has more or less 100 kcal. Of course, the nutrient content may fluctuate depending on the type and manner of preparation of this vegetable and the type of potato.

One of the most healthy version are sweet potatoes, also called batatas, while they are not the same potatoes as other types because they belong to the morning glory family, not to the nightshade – like other potatoes. Why are sweet potatoes they more healthy than other types? It is caused by the presence of carotenoids that give them characteristic orange color, where pink, orange, yellow, and green varieties are also high in beta-carotene needed for the immune system, healthy skin, eyes, and vision. Moreover, that is not the end of chemicals that are valuable for health. Batatas are rich in iron, zinc, calcium, magnesium, vitamin A, vitamin B complex, vitamin C, and vitamin E. They are also rich in lutein that is another after beta-carotene good for eyes and vision. Vitamin B, in particular, is crucial to maintaining neurological health. It helps in making beneficial molecules in the brain, including serotonin, dopamine, and norepinephrine. Potatoes also contain anthocyanins being effective antioxidants as well as hepatoprotective. These vegetables also contain antioxidants, substances that prevent the formation of harmful free radicals. The accumulation of free radicals in the body promotes the development of chronic diseases [3].

Interestingly, potatoes are a source of starch, so-called resistant starch, which, if not digested in the small intestine, gets to the large intestine and nourishes the beneficial intestinal bacteria there [4]. This type of starch benefits the body by controlling blood sugar levels and insulin sensitivity. Another important nutrient contained in potatoes is choline. It helps to maintain the structure of cell membranes, the transmission of nerve impulses, and fat absorption. It is also essential to early brain development. A single potato 57 mg contains this ingredient. The requirement of an adult man for this ingredient is 550 mg, and for women, 425 mg per day.

The dark side of potatoes

Most of us know that potatoes are poisonous before we boil them. They contain a solanine molecule that can cause severe food poisoning; luckily, it is rarely fatal or dangerous. That compound is also present in many fruits and vegetables that grow and are not mature enough to eat. The most frequent symptom appearing after the solanine consumption is a fever, diarrhea, and rash. Solanine is harmful only when potatoes are raw.

What is interesting, recent studies show that solanine may inhibit many cancer cells, including human colon, liver, cervical, lymphoma, and stomach cancer cells. It is also used as a deterrent for insects and other animals which are feeding on plants. Another harmful substance is chaconine. It has similar properties to solanine, causing the raw potato a bitter taste [5]. It also works as a repellent towards insects, being a natural shield against the consumption of non-mature potatoes.

What you certainly do not know about potatoes – interesting facts

  • In the 18th-century potato, blossoms were commonly used among the wealthy as a decoration of an outfit or hair. It started because Marie Antoinette loved them, and she used to put them in her hair and her husband Ludwik XVI put one in his buttonhole. Because the royal couple had a significant influence on fashion and cultural trends, they inspired other members of the French aristocracy to use potato blossoms as decoration. This situation was a part of an attempt to encourage farmers to plant this new vegetable and consumers to eat this novelty [6, 7].
  • Potatoes are the most popular vegetables to make alcoholic beverages like vodka. It is because they contain many sugars that can be transformed into alcohol under the fermentation process.
  • Potatoes can grow on a large spectrum of heights. It is seen from the sea level up to 4700 m above sea level, but there is no limit. In October 1995, NASA and the University of Wisconsin, Madison successfully grew potatoes in space, making it the first space to grow vegetables. This experiment gives hope for feeding astronauts during long space voyages and successfully setting up space colonies in the long run.

Summary

Potatoes can be prepared in many ways, boiled, baked, in the form of mousse, or fries, while they cannot be consumed raw due to chemicals that could lead to fever and stomach problems. They contain many beneficial ingredients, including potassium, phosphorus, magnesium, zinc, and iron, essential for healthy bones. They are one of the main sources used for the preparation of beverages and are served around the whole world due to their characteristic taste. These vegetables have been served for many decades, and they easily grow even in cold regions, making them extremely popular around the whole world.

This article is a joint work of Karol Kuryłek (Faculty of Chemistry, University of Warsaw), Agnieszka Pregowska (Institute of Fundamental Technological Research, Polish Academy of Sciences), and Magdalena Osial (Faculty of Chemistry, University of Warsaw) as a part of the Science Embassy project. Image Credit: Agnieszka Pregowska.

References

[1] Singh, J., Advances in Potato Chemistry and Technology, ‎ Academic Press; Edycja 2nd ed., 2016

[2] Friedman, M., Chemistry, Biochemistry, and Dietary Role of Potato Polyphenols. A Review, Journal of Agricultural and Food Chemistry 1997, 5(5), 1523–1540 DOI: 10.1021/jf960900s

[3] Mangge, H., Becker, K., Fuchs, D., Gostner, J. M., Antioxidants, inflammation and cardiovascular disease, World Journal of Cardiology 2014, 6(6), 462–477 DOI:10.4330/wjc.v6.i6.462

[4] Higgins, J. A., Resistant starch: metabolic effects and potential health benefits. Journal of AOAC International 2004, 87(3), 761–8

[5] Phillips, B. J., Hughes, J. A,, Phillips, J. C., Walters,  D. G., Anderson, D., Tahourdin, C. S., A study of the toxic hazard that might be associated with the consumption of green potato tops, Food and Chemical Toxicology 1996, 34(5), 439–48 DOI: 10.1016/0278–6915(96)87354–6.

[6] Hawkes, J. G., History of the potato. In: Harris P.M. (eds) The Potato Crop. World Crop Series. Springer, Dordrecht, 1992 DOI: 10.1007/978-94-011-2340-2_1

[7] Hawkes, J. G., Francisco-Ortega, J., The early history of the potato in Europe, Euphytica 1993, 70, 1–7 DOI: 10.1007/BF00029633