   #copyright

Potato

2007 Schools Wikipedia Selection. Related subjects: Food and agriculture

                    iPotato
           Scientific classification

   Kingdom:  Plantae
   Division: Magnoliophyta
   Class:    Magnoliopsida
   Subclass: Asteridae
   Order:    Solanales
   Family:   Solanaceae
   Genus:    Solanum
   Species:  S. tuberosum

                                Binomial name

   Solanum tuberosum
   L.

   The potato (Solanum tuberosum) is a perennial plant of the Solanaceae,
   or nightshade, family, commonly grown for its starchy tuber. Potatoes
   are the world's most widely grown tuber crop, and the fourth largest
   crop in terms of fresh produce (after rice, wheat, and maize), but this
   ranking is inflated due to the high water content of fresh potatoes
   relative to that of other crops. The potato originated in South
   America, somewhere in present-day Chile or Peru. Potatoes are important
   to the culture of the Andes, where farmers grow many different
   varieties that have a remarkable diversity of colors and shapes.
   Potatoes spread to the rest of the world after European contact with
   the Americas in the late 1400s and early 1500s and have since become an
   important field crop.

Botanical description

   Potato plant
   Enlarge
   Potato plant

   Potato plants have a low-growing habit and bear white to purple flowers
   with yellow stamens.

   Potato varieties bear flowers containing asexual parts. Flowers are
   mostly cross-pollinated by other potato plants, including by insects,
   but a substantial amount of self-fertilizing occurs. Any potato variety
   can also be propagated vegetatively by planting pieces of existing
   tubers, cut to include at least one eye. Some commercial varieties of
   potatoes do not produce seeds at all (they bear imperfect, single-sex
   flowers) and are propagated only from tuber pieces. Confusingly, these
   pieces can bear the name "seed potatoes".

   After potato plants flower, some varieties will produce small green
   fruit that look similar to green cherry-tomatoes. These produce seeds
   like other fruits. Each of the fruits can contain up to 300 true seeds.
   One can separate seeds from the fruits by putting them in a blender on
   a slow speed with some water, then leaving them in water for a day so
   that the seeds will sink and the rest of the fruit will float. However,
   some horticulturists sell chimeras made by grafting a tomato plant onto
   a potato plant, which can produce both edible tomatoes and potatoes.

Production

   According to the Food and Agriculture Organization, the worldwide
   production of potatoes in 2005 was 322 million metric tons (710 billion
   pounds) which makes it the fifth highest production crop in the world.

Food value

          Potato, raw, with peel
   Nutritional value per 100 g
          Energy 80 kcal   320 kJ

   Carbohydrates                   19 g
   - Starch  15 g
   - Dietary fibre  2.2 g
   Fat                             0.1 g
   Protein                         2 g
   Water                           75 g
   Thiamin (Vit. B1)  0.08 mg      6%
   Riboflavin (Vit. B2)  0.03 mg   2%
   Niacin (Vit. B3)  1.1 mg        7%
   Vitamin B6  0.25 mg             19%
   Vitamin C  20 mg                33%
   Calcium  12 mg                  1%
   Iron  1.8 mg                    14%
   Magnesium  23 mg                6%
   Phosphorus  57 mg               8%
   Potassium  421 mg               9%
   Sodium  6 mg                    0%
      Percentages are relative to US
   recommendations for adults.

   Nutritionally, potatoes are best known for their carbohydrate content
   (approximately 26 grams in a medium potato. Starch is the predominant
   form of carbohydrate found in potatoes. A small but significant portion
   of the starch in potatoes is resistant to enzymatic digestion in the
   stomach and small intestine and, thus, reaches the large intestine
   essentially intact. This portion of starch, referred to as “resistant
   starch,” is considered to have similar physiological effects and health
   benefits of fibre (e.g., provide bulk, offer protection against colon
   cancer, improve glucose tolerance and insulin sensitivity, lower plasma
   cholesterol and triglyceride concentrations, increase satiety, and
   possibly even reduce fat storage) (Cummings et al. 1996; Hylla et al
   1998; Raban et al. 1994). The amount of resistant starch found in
   potatoes is highly dependent upon preparation methods. Cooking and then
   cooling potatoes significantly increases 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 a number of important vitamins and minerals. A medium
   potato (5.3 oz) with the skin provides 27 mg 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, phosphorous, iron, and zinc. Moreover, the fiber content of
   a potato with skin (2 grams) equals that of many whole grain breads,
   pastas, and cereals. In addition to vitamins, minerals and fiber,
   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 a myth. While the skin does contain
   approximately half of the total dietary fibre, the majority (> 50%) of
   the nutrients are found within the potato itself The cooking method
   used can significantly impact the nutrient availability of the potato.

   New and fingerling potatoes offer the advantage that they contain fewer
   toxic chemicals. Such potatoes offer an excellent source of nutrition.
   Peeled, long-stored potatoes have less nutritional value, although they
   still have potassium and vitamin C.

   Potatoes are often broadly classified as “high” on the glycemic index
   (GI) and; thus, are frequently 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 the type (i.e., red vs. russet vs.
   white vs. Prince Edward), origin (i.e., where it was grown),
   preparation methods (i.e., cooking method, whether it is eating hot or
   cold, whether it is mashed or cubed or consumed whole, etc), and what
   it is consumed with (i.e., the addition of various high fat or high
   protein toppings)(Fernandes et al. 2005).

Cooking

General Methods

   Potatoes are prepared in many ways: skin-on or peeled, whole or cut up,
   with seasonings or without. The only requirement involves cooking to
   break down the starch. Most potato dishes are served hot, but some are
   first cooked then served cold, notably potato salad and potato
   chips/crisps.

   Common dishes are: mashed potatoes, which are boiled, peeled (sometimes
   not), and mashed with milk and butter; whole baked potatoes; boiled or
   steamed potatoes; French-fried potatoes or chips; cut into cubes and
   roasted; scalloped, diced, or sliced and fried (home fries); grated
   into small thin strips and fried (hash browns); grated and formed into
   dumplings, Rösti or potato pancakes. Potatoes, unlike many foods, can
   also be easily cooked in a microwave oven and still retain nearly all
   of their nutritional value, provided that they are covered in
   ventilated plastic wrap to prevent moisture from escaping—this method
   produces a meal very similar to a baked potato. Potato chunks also
   commonly appear as a stew ingredient.

Regional dishes

   Mashed potatoes form a major component of several traditional dishes
   from the British Isles such as shepherd's pie, bubble and squeak, champ
   and the 'mashit tatties' (Scots language) which accompany haggis. They
   are also often sautéed to accompany a meal.

   Potatoes are very popular in continental Europe as well. In Italy, they
   serve to make a type of pasta called gnocchi. Potatoes form one of the
   main ingredients in many soups such as the pseudo-French vichyssoise
   and Albanian potato and cabbage soup.

   In the United States, potatoes have become one of the most widely
   consumed crops, and thus have a variety of preparation methods and
   condiments. One popular favorite involves a baked potato with cheddar
   cheese (or sour cream and chives) on top, and in New England "smashed
   potatoes" (a chunkier variation on mashed potatoes, retaining the peel)
   have great popularity.

   In Scandinavia, especially Denmark, Sweden and Finland, newly
   harvested, early ripening varieties are considered a special delicacy.
   Boiled whole and served with dill, these "new potatoes" are
   traditionally consumed together with pickled Baltic herring.

   A traditional Canary Islands dish is Canarian wrinkly potatoes or Papas
   arragudas.

   A traditional Acadian dish from New Brunswick is known as poutine
   râpée. The Acadian poutine is a ball of grated and mashed potato,
   salted, sometimes filled with pork in the centre, and boiled. The
   result is a moist ball about the size of a baseball. It is commonly
   eaten with salt and pepper or brown sugar. It is believed to have
   originated from the German Klöße, prepared by early German settlers who
   lived among the Acadians.

Toxic compounds in potatoes

   Potato plants
   Enlarge
   Potato plants

   Potatoes contain glycoalkaloids, toxic compounds, of which the most
   prevalent are solanine and chaconine. Cooking at high temperatures
   (over 170 °C or 340 °F) partly destroys these. The concentration of
   glycoalkaloid in wild potatoes suffices to produce toxic effects in
   humans. Glycoalkaloids occur in the greatest concentrations just
   underneath the skin of the tuber, and they increase with age and
   exposure to light. Glycoalkaloids may cause headaches, diarrhea, cramps
   and in severe cases coma and death; however, poisoning from potatoes
   occurs very rarely. Light exposure also causes greening, thus giving a
   visual clue as to areas of the tuber that may have become more toxic;
   however, this does not provide a definitive guide, as greening and
   glycoalkaloid accumulation can occur independently of each other. Some
   varieties of potato contain greater glycoalkaloid concentrations than
   others; breeders developing new varieties test for this, and sometimes
   have to discard an otherwise promising cultivar.

   Breeders try to keep solanine levels below 0.2 mg/g (200 ppmw).
   However, when even these commercial varieties turn green, they can
   approach concentrations of solanine of 1 mg/g (1000 ppmw). Some studies
   suggest that 200 mg of solanine can constitute a dangerous dose. This
   dose would require eating 1 average-sized spoiled potato or 4 to 9 good
   potatoes (over 3 pounds or 1.4 kg) at one time. The National Toxicology
   Program suggests that the average American consumes at most 12.5
   mg/person/day of solanine from potatoes. Dr. Douglas L. Holt, the State
   Extension Specialist for Food Safety at the University of Missouri -
   Columbia, notes that no reported cases of potato-source solanine
   poisoning have occurred in the U.S. in the last 50 years and most cases
   involved eating green potatoes or drinking potato-leaf tea.

   Solanine is also found in other plants, in particular the deadly
   nightshade. This poison affects the nervous system causing weakness and
   confusion. See Solanine for more information.
   Seed tuber with sproutsEarly Rose variety
   Enlarge
   Seed tuber with sprouts
   Early Rose variety
   Potato PlantingWashington
   Enlarge
   Potato Planting
   Washington

   See also List of poisonous plants

Cultivation

   Potatoes are generally grown from the eyes of another potato and not
   from seed. Home gardeners often plant a piece of potato with two or
   three eyes in a hill of mounded soil. Commercial growers plant potatoes
   as a row crop using seed tubers, young plants or microtubers and may
   mound the entire row.

   At harvest time, gardeners generally dig up potatoes with a three-prong
   "grape" (or "graip") or spading fork, but in larger plots, the plough
   can serve as the most expeditious implement for unearthing potatoes.
   Commercial harvesting is typically done with large potato harvesters
   which scoop up the plant and the surrounding earth. This is transported
   up an apron chain consisting of steel links several feet wide. This
   separates some of the dirt. The chain deposits into an area where
   further separation occurs. Different designs employ different systems
   at this point. The most complex designs use vine choppers and shakers,
   along with a blower system or "Flying Willard" to separate the potatoes
   from the plant. The result is then usually run past workers who
   continue to sort out plant material, stones, and rotten potatoes before
   the potatoes are continuously delivered to a wagon or truck. Further
   inspection and separation occurs when the potatoes are unloaded from
   the field vehicles and put into storage.

   Eliminating all root-weeds is desirable in potato cultivation. Three
   plowings, with necessary harrowings and rollings, are desirable if they
   can be accomplished before the appropriate planting time.

   It is important to harvest potatoes before heavy frosts begin, since
   field frost damages potatoes in the ground, and even cold weather makes
   potatoes more susceptible to bruising and possibly later rotting which
   can quickly ruin a large stored crop.

   Seed potato crops are 'rogued' in some countries to eliminate diseased
   plants or those of a different variety from the seed crop.
   Potato fieldFort Fairfield, Maine
   Enlarge
   Potato field
   Fort Fairfield, Maine

Pests

   A major pest of potato plants is the Colorado potato beetle.

   The potato root nematode is a microscopic worm that thrives on the
   roots, thus causing the potato plants to wilt. Since its eggs can
   survive in the soil for several years, crop rotation is recommended.

New potatoes

   Potatoes are generally cured after harvest to thicken the skin. Prior
   to curing, the skin is very thin and delicate and the potatoes are
   known as "New Potatoes" and are particularly flavorful. New potatoes
   are often harvested by the home gardener by "grabbling", i.e. pulling
   out the young tubers by hand while leaving the plant in place. In
   markets one sometimes finds thin-skinned varieties sold as new
   potatoes.

Storage

   Storage facilities need to be carefully designed to keep the potatoes
   alive and slow the natural process of decomposition, which involves the
   breakdown of starch. It is crucial that the storage area is dark, well
   ventilated and ideally maintained at a temperature of about 4 degrees
   Celsius. Potatoes must not be kept in a refrigerator. Cold temperatures
   convert potatoes' starch into sugar, which alters their taste. Under
   optimum conditions, potatoes can be stored for up to six months, but
   several weeks is the normal maximum.
   Retrieved from " http://en.wikipedia.org/wiki/Potato"
   This reference article is mainly selected from the English Wikipedia
   with only minor checks and changes (see www.wikipedia.org for details
   of authors and sources) and is available under the GNU Free
   Documentation License. See also our Disclaimer.
