| Spinach | |
|---|---|
| Spinach in flower | |
| Scientific classification | |
| Kingdom: | Plantae |
| (unranked): | Angiosperms |
| (unranked): | Eudicots |
| (unranked): | Core eudicots |
| Order: | Caryophyllales |
| Family: | Amaranthaceae, formerly Chenopodiaceae[4] |
| Genus: | Spinacia |
| Species: | S. oleracea |
| Binomial name | |
| Spinacia oleracea L. |
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Spinach (Spinacia oleracea) is an edible flowering plant in the family of Amaranthaceae. It is native to central and southwestern Asia. It is an annual plant (rarely biennial), which grows to a height of up to 30 cm. Spinach may survive over winter in temperate regions. The leaves are alternate, simple, ovate to triangular-based, very variable in size from about 2–30 cm long and 1–15 cm broad, with larger leaves at the base of the plant and small leaves higher on the flowering stem. The flowers are inconspicuous, yellow-green, 3–4 mm diameter, maturing into a small, hard, dry, lumpy fruit cluster 5–10 mm across containing several seeds.
Common spinach, Spinacia oleracea, was long considered to be in the Chinopodiaceae family, but in 2003 the Chinopodiaceae family was combined with the Amaranthaceae family under the family name 'Amaranthaceae' in the order Caryophyllales. Within the Amaranthaceae family there are now a subfamily Amaranthoideae and a subfamily Chenopodioideae, for the amaranths and the chenopods, respectively.
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The English word "spinach" dates to 1530, and is from espinache (Fr. épinard), of uncertain origin. The traditional view derives it from O.Prov. espinarc, which perhaps is via Catalan espinac, from Andalusian Arabic asbinakh (اسبيناخ), from Arabic es-sabaanikh (السبانخ), from Persian اسپاناخ aspanakh, meaning roughly "green hand",[1] but the multiplicity of forms makes the theory doubtful.[2]
Spinach is thought to have originated in ancient Persia (modern Iran and neighboring countries). Arab traders carried spinach into India, and then the plant was introduced into ancient China, where it was known as "Persian vegetable" (bōsī cài; 波斯菜; present:菠菜). The earliest available record of the spinach plant was recorded in Chinese, stating it was introduced into China via Nepal (probably in 647 AD).[3]
In AD 827, the Saracens introduced spinach to Sicily. The first written evidence of spinach in the Mediterranean are in three 10th-century works, the medical work by al-Razi (known as Rhazes in the West) and in two agricultural treatises, one by Ibn Wahshiya and the other by Qustus al-Rumi. Spinach became a popular vegetable in the Arab Mediterranean, and arrived in Spain by the latter part of the 12th century, where the great Arab agronomist Ibn al-'Awwam called it the "captain of leafy greens". Spinach was also the subject of a special treatise in the 11th century by Ibn Hajjaj.[4]
The prickly-seeded form of spinach was known in Germany by no later than the 13th century, though the smooth-seeded form was not described till 1552. (The smooth-seeded form is used in modern commercial production.)[3]
Spinach first appeared in England and France in the 14th century, probably via Spain, and it gained quick popularity because it appeared in early spring, when other vegetables were scarce and when Lenten dietary restrictions discouraged consumption of other foods. Spinach is mentioned in the first known English cookbook, The Forme of Cury (1390), where it is referred to as spinnedge and/or spynoches.[5] Smooth-seeded spinach was described in 1552.[3]
In 1533, Catherine de' Medici became queen of France; she so fancied spinach that she insisted it be served at every meal. To this day, dishes made with spinach are known as "Florentine", reflecting Catherine's birth in Florence.[6]
During World War I, wine fortified with spinach juice was given to French soldiers weakened by hemorrhage.[7]
| Nutritional value per 100 g (3.5 oz) | |
|---|---|
| Energy | 97 kJ (23 kcal) |
| Carbohydrates | 3.6 g |
| - Sugars | 0.4 g |
| - Dietary fiber | 2.2 g |
| Fat | 0.4 g |
| Protein | 2.2 g |
| Vitamin A equiv. | 469 μg (59%) |
| Vitamin A | 9400 IU |
| - beta-carotene | 5626 μg (52%) |
| - lutein and zeaxanthin | 12198 μg |
| Folate (vit. B9) | 194 μg (49%) |
| Vitamin C | 28 mg (34%) |
| Vitamin E | 2 mg (13%) |
| Vitamin K | 483 μg (460%) |
| Calcium | 99 mg (10%) |
| Iron | 2.7 mg (21%) |
| Percentages are relative to US recommendations for adults. Source: USDA Nutrient Database |
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Spinach has a high nutritional value and is extremely rich in antioxidants, especially when fresh, steamed, or quickly boiled. It is a rich source of vitamin A (and especially high in lutein), vitamin C, vitamin E, vitamin K, magnesium, manganese, folate, betaine, iron, vitamin B2, calcium, potassium, vitamin B6, folic acid, copper, protein, phosphorus, zinc, niacin, selenium and omega-3 fatty acids. Recently, opioid peptides called rubiscolins have also been found in spinach.
Polyglutamyl folate (vitamin B9 or folic acid) is a vital constituent of cells, and spinach is a good source of folic acid. Boiling spinach can more than halve the level of folate left in the spinach, but microwaving does not affect folate content.[8] Vitamin B9 was first isolated from spinach in 1941.[9]
Spinach, along with other green leafy vegetables,[10] is considered to be a rich source of iron. For example, the United States Department of Agriculture states that a 180 g serving of boiled spinach contains 6.43 mg of iron, whereas one 170 g ground hamburger patty contains at most 4.42 mg.[11]
The bioavailability of iron is dependent on its absorption, which is influenced by a number of factors. Iron enters the body in two forms: heme iron and nonheme iron. All of the iron in grains and vegetables, and about three-fifths of the iron in animal food sources (meats), is nonheme iron. The remaining portion from meats is heme iron.[12]
The larger portion of dietary iron (nonheme) is absorbed slowly in its many food sources, including spinach. This absorption may vary widely depending on the presence of binders, such as fiber, or enhancers, such as vitamin C. Therefore, the body's absorption of nonheme iron can be improved by consuming foods that are rich in vitamin C. However, spinach contains iron absorption-inhibiting substances, including high levels of oxalate, which can bind to the iron to form ferrous oxalate and render much of the iron in spinach unusable by the body.[13] In addition to preventing absorption and use, high levels of oxalates remove iron from the body.[14] But some studies have found that the addition of oxalic acid to the diet may improve iron absorption in rats over a diet with spinach without additional oxalic acid.[15]
Spinach also has a high calcium content. However, the oxalate content in spinach also binds with calcium, decreasing its absorption. Calcium and zinc also limit iron absorption.[16] The calcium in spinach is the least bioavailable of calcium sources.[17] By way of comparison, the body can absorb about half of the calcium present in broccoli, yet only around 5% of the calcium in spinach.
A distinction can be made between older varieties of spinach and more modern ones. Older varieties tend to bolt too early in warm conditions. Newer varieties tend to grow more rapidly, but have less of an inclination to run up to seed. The older varieties have narrower leaves and tend to have a stronger and more bitter taste. Most newer varieties have broader leaves and round seeds.
There are three basic types of spinach:
Spinach is sold loose, bunched, in prepackaged bags, canned, or frozen. Fresh spinach loses much of its nutritional value with storage of more than a few days.[18] While refrigeration slows this effect to about eight days, spinach will lose most of its folate and carotenoid content, so for longer storage it is frozen, cooked and frozen, or canned. Storage in the freezer can be for up to eight months.
The Environmental Working Group reported spinach is one of the dozen most heavily pesticide-contaminated produce products.[19] The most common pesticides found on spinach are permethrin, dimethoate, and DDT.
Spinach is packaged in air, or in nitrogen gas to extend shelf life. Some packaged spinach is exposed to radiation to kill any harmful bacteria that may be on the leaves. The Food and Drug Administration approves of irradiation of spinach leaves up to 4.0 kilograys (kGy); however, there is concern that using radiation to sanitize spinach depletes the leaves of their nutritional value. Researchers at the Agricultural Research Service experimentally tested the concentrations of vitamins C, E, K, B9, and four other carotenoids in packaged spinach following irradiation. They found that with increasing level of irradiation, four nutrients showed little or no change. Those nutrients include vitamins B9, E, K, and the carotenoid neoxanthin. This study showed the irradiation of packaged spinach to have little or no change to the nutritional value of the crop, and the health benefits of irradiating packed spinach seem to outweigh the health risks of transmitting harmful bacteria.[20]
The cartoon character Popeye the Sailor Man is portrayed as having a strong affinity for spinach, becoming physically stronger after consuming it. A frequently circulated story claims this portrayal was based on faulty calculations of the iron content.[21][22][23] In the story, German scientist Emil von Wolff misplaced a decimal point in an 1870 measurement of spinach's iron content, leading to an iron value 10 times higher than it should have been, and this faulty measurement was not noticed until the 1930s. However, recent research has shown that this is just another long-standing myth, and spinach was chosen and promoted in Popeye for its vitamin A content alone.[24]
Spinach, along with Brussels sprouts and other green vegetables, is often portrayed in children's shows to be undesirable.[21]
Driven by fresh-market use, the consumption of Spinacia oleracea has been on the rise in the United States. Per capita use of fresh-market spinach averaged 1 kg during 2004–06, the highest since the mid-1940s. The fresh market now accounts for about three-fourths of all U.S. spinach consumed. Much of the growth over the past decade has been due to sales of triple-washed cello-packed spinach and, more recently, baby spinach. These packaged products have been one of the fastest-growing segments of the packaged salad industry.
The United States is the world’s second-largest producer of spinach, with 3% of world output, following China (PRC), which accounts for 85% of output.
California (73% of 2004–06 U.S. output), Arizona (12%), and New Jersey (3%) are the top producing states, with 12 other states reporting production of at least 100 acres (2002 census). Over the 2004–06 period, U.S. growers produced an average of 867 million pounds of spinach for all uses, with about three-fourths sold into the fresh-market (includes fresh-cut/processed). According to the 2002 Census of Agriculture, spinach was grown on 1,109 U.S. farms—down 17% from 1997, but about the same number as in 1987.
The farm value of U.S. spinach crops (fresh and processed) averaged $175 million during 2004–06, with fresh market spinach accounting for 94%. The value of fresh market spinach has more than doubled over the past decade as stronger demand has boosted production, while inflation-adjusted prices largely remained constant. California accounts for about three-fourths of the value of both the fresh and processing spinach crops.
Like other cool-season leafy crops, most (about 96%) of the fresh spinach consumed in the United States is produced domestically. Although rising, imports (largely from Mexico) totaled about 23 million pounds in 2004–06, compared with 3 million pounds in 1994–06. During the last 10 years, exports (largely to Canada) have jumped 70 percent to 47 million pounds (2004–06), with much of the growth occurring earlier this decade.[25]
Per capita spinach consumption is greatest in the Northeast and Western US. About 80% of fresh-market spinach is purchased at retail and consumed at home, while 91% of processed spinach is consumed at home. Per capita spinach use is strongest among Asians, highest among women 40 and older, and weakest among teenage girls.[26]
In September 2006, there was an outbreak of disease caused by the E. coli strain O157:H7 in 21 U.S. states. Over a hundred cases were reported, including five deaths. The E. coli was linked to bags of fresh spinach, after which the FDA issued a warning not to eat uncooked fresh spinach or products containing it. The U.S. Food and Drug Administration (FDA) issued a press release updating the available information. According to the FDA release on 2006-10-4, 192 cases of E. coli O157:H7 infection have been reported to the Centers for Disease Control and Prevention (CDC), including 30 cases of hemolytic uremic syndrome; there was one death and 98 hospitalizations. The infection affected 26 states. By early 2007, there were 206 illnesses and three deaths attributed to E. coli-tainted spinach.
Based on epidemiological and laboratory evidence, the FDA determined that the implicated spinach originated from an organic spinach field grown by Mission Organics and processed by Natural Selection Foods LLC of San Juan Bautista, California. The FDA speculated the spinach had been tainted by irrigation water contaminated with wild pig feces because feral pigs were seen in the vicinity of the implicated ranch.
On August 30, 2007, 8,000 cartons of spinach (from Metz Fresh, a King City-based grower and shipper, Salinas Valley, California) were recalled after Salmonella was discovered upon routine testing. Consumer advocates and some lawmakers complained it exposed big gaps in food safety, even if 90% of suspect vegetables did not reach the shelves.[27]
Spoon, Professor (2005) Why is my custard lumpy? BATH:Absolute Press. p43. ISBN: 1-904573-34-7