Wednesday, August 31, 2011

Spinach Cultivation


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
spinach plants

'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.Contents

Etymology

 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

spinach seeds
spinach seeds
Arabic asbinakh , from Arabic es-sabaanikh , from Persian  aspanakh, meaning roughly "green hand", but the multiplicity of forms makes the theory doubtful.

History

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; present:. The earliest available record of the spinach plant was recorded in Chinese, stating it was introduced into China via Nepal (probably in 647 AD).

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.

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.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. Smooth-seeded spinach was described in 1552.

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.

During World War I, wine fortified with spinach juice was given to French soldiers weakened by hemorrhage.

Nutrition

Spinach, rawNutritional 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%)

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. Vitamin B9 was first isolated from spinach in 1941.

Iron

Spinach, along with other green leafy vegetables, 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.

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.

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[citation needed]. 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. In addition to preventing absorption and use, high levels of oxalates remove iron from the body. 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.

Calcium

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. The calcium in spinach is the least bioavailable of calcium sources. 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.

Pureed spinach and homemade cheese with spiced flatbread(makki di roti) from India

Types of 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.

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.
The following are some of the varieties usually cultivated :-

1. Savoy : Savoy has dark green, crinkly and curly leaves. It is the type sold in fresh bunches in
                  most  supermarkets.

2. Bloomsdale : Bloomsdale   is somewhat resistant to bolting.

3. Merlo Nero : This is a mild variety from Italy . This is the common heirloom variety.

4. Viroflay : This is a very large spinach with great yields .

5. Semi-savoy :  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', a widely grown variety, has good resistance to running up to seed.

Production, marketing and storage

 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.

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.



spinach seeds germinationUnited States

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.

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