The potato is a starchy, tuberous crop from the perennial Solanum tuberosum of the Solanaceae family. The word potato may refer to the plant itself as well. In the region of the Andes, there are some other closely related cultivated potato species. Potatoes are the world’s fourth largest food crop, following rice, wheat, and maize.
Wild potato species occur from the United States to Uruguay and Chile. Genetic testing of the wide variety of cultivars and wild species suggest that the potato has a single origin in the area of southern Peru, from a species in the Solanum brevicaule complex. However, although Peru is essentially the birthplace of the potato, today over 99% of all cultivated potatoes worldwide are descendants of a subspecies indigenous to south-central Chile. Based on historical records, local agriculturalists, and DNA analyses, the most widely cultivated variety worldwide, Solanum tuberosum ssp. tuberosum, is believed to be indigenous to Chiloé Archipelago where it was cultivated as long as 10,000 years ago.
The potato was introduced to Europe in 1536, and subsequently by European mariners to territories and ports throughout the world. Thousands of varieties persist in the Andes, where over 100 varieties might be found in a single valley, and a dozen or more might be maintained by a single agricultural household. Once established in Europe, the potato soon became an important food staple and field crop. But lack of genetic diversity, due to the fact that very few varieties were initially introduced, left the crop vulnerable to disease. In 1845, a plant disease known as late blight, caused by the fungus-like oomycete Phytophthora infestans, spread rapidly through the poorer communities of western Ireland, resulting in the crop failures that led to the Great Irish Famine.
The annual diet of an average global citizen in the first decade of the twenty-first century would include about 33 kilograms (or 73 lbs.) of potato. However, the local importance of potato is extremely variable and rapidly changing. The potato remains an essential crop in Europe (especially eastern and central Europe), where per capita production is still the highest in the world, but the most rapid expansion of potato over the past few decades has occurred in southern and eastern Asia. China is now the world’s largest potato producing country, and nearly a third of the world’s potatoes are harvested in China and India. More generally, the geographic shift of potato production has been away from wealthier countries toward lower-income areas of the world.
Potato plants are herbaceous perennials that grow about 60 cm high, depending on variety, the culms dying back after flowering. They bear white, pink, red, blue or purple flowers with yellow stamens resembling those of other Solanaceous species such as tomato and aubergine. The tubers of varieties with white flowers generally have white skins, while those of varieties with colored flowers tend to have pinkish skins. Potatoes are cross-pollinated mostly by insects, including bumblebees that carry pollen from other potato plants, but a substantial amount of self-fertilizing occurs as well. Tubers form in response to decreasing day length, although this tendency has been minimized in commercial varieties.
Potato plantsAfter potato plants flower, some varieties will produce small green fruits that resemble green cherry tomatoes, each containing up to 300 true seeds. Potato fruit contains large amounts of the toxic alkaloid solanine, and is therefore unsuitable for consumption.
All new potato varieties are grown from seeds, also called “true seed” or “botanical seed” to distinguish it from seed tubers. By finely chopping the fruit and soaking it in water, the seeds will separate from the flesh by sinking to the bottom after about a day (the remnants of the fruit will float). Any potato variety can also be propagated vegetatively by planting tubers, pieces of tubers, cut to include at least one or two eyes, or also by cuttings, a practice used in greenhouses for the production of healthy seed tubers. Some commercial potato varieties do not produce seeds at all (they bear imperfect flowers) and are propagated only from tuber pieces. Confusingly, these tubers or tuber pieces are called “seed potatoes”.
Nutritionally, potatoes are best known for their carbohydrate content (approximately 26 grams in a medium potato). The predominant form of this carbohydrate is starch. A small but significant portion of this starch is resistant to digestion by enzymes in the stomach and small intestine, and so reaches the large intestine essentially intact. This resistant starch is considered to have similar physiological effects and health benefits as fiber: it provides bulk, offers protection against colon cancer, improves glucose tolerance and insulin sensitivity, lowers plasma cholesterol and triglyceride concentrations, increases satiety, and possibly even reduces fat storage (Cummings et al. 1996; Hylla et al. 1998; Raban et al. 1994). The amount of resistant starch in potatoes depends much on preparation methods. Cooking and then cooling potatoes significantly increased resistant starch. For example, cooked potato starch contains about 7% resistant starch, which increases to about 13% upon cooling (Englyst et al. 1992).
Potatoes contain vitamins and minerals that have been identified as vital to human nutrition. Humans can subsist healthily on a diet of potatoes and milk; the latter supplies Vitamin A and Vitamin D. A medium potato (150g/5.3 oz) with the skin provides 27 mg of vitamin C (45% of the Daily Value (DV)), 620 mg of potassium (18% of DV), 0.2 mg vitamin B6 (10% of DV) and trace amounts of thiamin, riboflavin, folate, niacin, magnesium, phosphorus, iron, and zinc. Moreover, the fiber content of a potato with skin (2 grams) equals that of many whole grain breads, pastas, and cereals. Potatoes also contain an assortment of phytochemicals, such as carotenoids and polyphenols. The notion that “all of the potato’s nutrients” are found in the skin is an urban legend. While the skin does contain approximately half of the total dietary fiber, more than 50% of the nutrients are found within the potato itself. The cooking method used can significantly impact the nutrient availability of the potato.
Almost all the protein content of a potato is contained in a thin layer just under its skin. Citation needed] This is evident when the skin of a boiled potato is carefully peeled; it appears as a yellowish film. For maximum utilisation of this small, but valuable dietary source of protein, potatoes should be consumed whole, or peeled after cooking.
Potatoes are often broadly classified as high on the glycemic index (GI) and so are often excluded from the diets of individuals trying to follow a “low GI” eating regimen. In fact, the GI of potatoes can vary considerably depending on type (such as red, russet, white, or Prince Edward), origin (where it was grown), preparation methods (i.e., cooking method, whether it is eaten hot or cold, whether it is mashed or cubed or consumed whole, etc), and with what it is consumed (i.e., the addition of various high fat or high protein toppings) (Fernandes et al. 2006).
Number of recipes containing potatoes can be Found in Ayesha’s Kitchen: