Spinach

Spinach
Spinach in flower
Scientific classification
Kingdom: Plantae Division: Magnoliophyta Class: Magnoliopsida Order: Caryophyllales Family: Amaranthaceae Genus: Spinacia Species: S. oleracea
Binomial name
Spinacia oleracea L.

Spinach is an annual plant, Spinacia oleracea, of the flowering plant family of Amaranthaceae and order Caryophyllales, which is popularly cultivated as a leaf vegetable. The term also is used for the succulent, edible leaves of this plant.

valued for high 8888 and iron, although its reputation as a source of iron is somewhat exaggerated, due to the fact that the plant contains oxalic acid which impacts the amount of iron and calcium actually avaiable for absorption by the body (herbst 2001; Bender and Bender 2005).

Some other species of plants also are commonly called spinach, including New Zealand spinach, Tetrogonia expansa in the Aizoaceae family, and Mountain spinach, Atriplex hortense in the Amaranthaceae family.

Description

Spinach belongs to the Amaranth family Amaranthaceae, a flowering plant family that contains about 160 genera and 2,400 species. Plants of this family have dark green leaves that are simple, opposite or alternate, with margins that are entire or coarsely toothed, and without stipules. The flowers are solitary or aggregated in cymes, spikes, or panicles and typically perfect (bisexual) and actinomorphic. The bracteate flowers are regular with 4-5 petals, often joined. There are 1-5 stamens. The hypogynous ovary has 3-5 joined sepals.

Spinach, Spinacia oleracea, is an annual plant native to central and southwestern Asia. It grows to a height of up to 30 centimeters (cm). The leaves are alternate, simple, and ovate to triangular, either flat or curled. The leaves are 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 millimeters across containing several seeds.

Spinach requires cool weather and may survive over winter in temperate regions.

Culinary Information

Nutrition

In popular folklore, spinach is a rich source of iron. In reality, a 60 gram serving of boiled spinach contains around 1.9 mg of iron (slightly more when eaten raw). A good many green vegetables contain less than 1 mg of iron for an equivalent serving. Hence spinach does contain a relatively high level of iron for a vegetable, but its consumption does not have special health connotations as folklore might suggest.

The myth about spinach and its high iron content may have first been propagated by Dr. E. von Wolf in 1870, because a misplaced decimal point in his publication led to an iron-content figure that was ten times too high. In 1937, German chemists reinvestigated this "miracle vegetable" and corrected the mistake. It was described by T.J. Hamblin in British Medical Journal, December 1981.

Ultimately, the bioavailability of iron is dependent on its absorption. This is influenced by a number of factors. Iron enters the body in two forms: nonheme iron and heme 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 much smaller remaining portion from meats is heme iron (Williams, 1993).

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 non-heme iron can be improved by consuming foods that are rich in vitamin C. However, spinach contains high levels of oxalate. Oxalates bind to iron to form ferrous oxalate and remove iron from the body. Therefore, a diet high in oxalate (or phosphate or phytate) leads to a decrease in iron absorption.

Spinach also has a high calcium content. However, the oxalate content in spinach binds with calcium decreasing its absorption. 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. Oxalate is one of a number of factors that can contribute to gout and kidney stones. Equally or more notable factors contributing to calcium stones are: genetic tendency, high intake of animal protein, excess calcium intake, excess vitamin D, prolonged immobility, hyperparathyroidism, renal tubular acidosis, and excess dietary fiber (Williams, 1993).

Boiled Spinach and Corn flour paratha from Punjab, India.

Spinach still has a large nutritional value, especially when fresh, steamed, or quickly boiled. It is a rich source of vitamin A, vitamin C, vitamin E, vitamin K, magnesium, and several vital antioxidants. Recently, opioid peptides called rubiscolins have also been found in spinach. It is a source of folic acid, and this vitamin was first purified from spinach. To benefit from the folate in spinach, it is better to steam it than to boil it. Boiling spinach for four minutes can halve the level of folate.

Types of spinach

A distinction can be made between older varieties of spinach and more modern varieties. 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 3 basic types of Spinach:

• Savoy has dark green, crinkly and curly leaves. It is the type sold in fresh bunches in most supermarkets. One heirloom variety of savoy is Bloomsdale, which is somewhat resistant to bolting.

• Flat/smooth leaf spinach has broad smooth leaves that are easier to clean than savoy. This type is often grown for canned and frozen spinach, as well as soups, baby foods, and processed foods.

• Semi-savoy is a hybrid variety with slightly crinkled leaves. It has the same texture as savoy, but it is not as difficult to clean. It is grown for both fresh market and processing. Five Star is a widely grown variety and has good resistance to running up to seed.

In Australia, a significant percentage of people erroneously identify chard (locally known as silverbeet) as spinach, despite the fact that both spinach and chard are labelled appropriately in stores.

Production, marketing and storage

Spinach output in 2005

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. 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.

Reheating spinach leftovers may cause the formation of poisonous compounds by certain bacteria that thrive on prepared nitrate-rich foods, such as spinach and many other green vegetables. These bacteria can convert the nitrates into nitrites, which may be especially harmful to infants younger than six months. The nitrate-converting enzymes produced by the bacteria can convert even more at elevated temperatures during the second heating. For older children and adults, small concentrations of nitrites are harmless, although formation of nitrosamine compounds from the nitrites could be of concern for adults as well.

Spinach in popular culture

Popeye the Sailor has a strong affinity for spinach, becoming much stronger after consuming it. This is partially due to the iron content being mistakenly reported ten times the actual value, a value that was unchecked during the 1930's.

2006 United States E. coli outbreak

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In September 2006, there was an outbreak of disease caused by the E. coli strain O157:H7 in 21 U.S. states. On 2006-09-14, 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. As of 2006-09-24, over a hundred cases have been reported, including five deaths.

The U.S. Food and Drug Administration issued a press release updating the available information. According to the FDA release as 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, FDA determined that the implicated spinach originated from an organich spinach field grown by Mission Organics and processed by Natural Selection Foods LLC of San Juan Bautista, California. The FDA speculated that the spinach had been tainted by irrigation water contaminated with cattle feces (one of the most common sources of E. coli poisoning), from a cattle ranch located near the land on which the spinach was grown.

2007 United States Salmonella outbreak

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 test. Consumer advocates and some lawmakers complained it exposed big gaps in food safety, even if 90% of suspect vegetable didn’t reach the shelves.

Other species called spinach

The name spinach has been applied to a number of leaf vegetables, both related and unrelated to spinach:

Related species

• Chard (Beta vulgaris, Amaranthaceae), also known as spinach beet or perpetual spinach.
• Orache (Atriplex species, Amaranthaceae), also called "French spinach" or "mountain spinach".
• Good King Henry (Chenopodium bonus-henricus, Amaranthaceae) and other Chenopodium species, also called "Lincolnshire spinach".

In Indonesia, the word bayam is applied both to certain species of amaranth commonly eaten as a leafy vegetable, and to spinach, which is rarely seen, only in certain supermarkets but well known from Popeye cartoons.

Unrelated species

• New Zealand spinach (Tetragonia, Aizoaceae).
• Water spinach (Convolvulaceae).
• Malabar spinach (Basellaceae).
• The greens of various nightshade, legume and cucurbit species are also known as spinach, wild spinach, African spinach, "Thermadorian spinach" or morogo (in Southern Africa).

References and external links

• D. Maue, S. Walia, S. Shore, M. Parkash, S. K. Walia, S. K. Walia (2005). "Prevalence of Multiple Antibiotic Resistant Bacteria in Ready-to-Eat Bagged Salads". American Society for Microbiology meeting. June 5-9, Atlanta. Abstract
• Overview of Spinach from Innvista
• Rogers, Jo. What Food is That?: and how healthy is it?. The Rocks, Sydney, NSW: Lansdowne Publishing Pty Ltd, 1990. ISBN 1-86302-823-4.
• Cardwell, Glenn. Spinach is a Good Source of What?. The Skeptic. Volume 25, No 2, Winter 2005. Pp 31-33. ISSN 0726-9897
• Blazey, Clive. The Australian Vegetable Garden: What's new is old. Sydney, NSW: New Holland Publishers, 1999. ISBN 1-86436-538-2
• Stanton, Rosemary. Complete Book of Food and Nutrition. Australia, Simon & Schuster, Revised Edition, 1995. ISBN 0-7318-0538-0
• Williams, S.R. (1993) Nutrition and Diet Therapy 7th ed. Mosby: St. Loius, MO

Wikibooks Cookbook has more about this subject:

Spinach

• The nutritional benefits of spinach were discussed in detail in the Skeptic magazine, (Winter 2005).
• Powell, D. and Chapman "Fresh and Risky" Food Safety Network, September 15, 2006

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