Source  : Health Canada. Canadian Nutrient File , 2010.

The benefits of asparagus

Very few studies have evaluated the specific benefits of asparagus on human health. However, several prospective and epidemiological studies have shown that a high consumption of vegetables and fruits decreases the risk of cardiovascular diseases ²⁵ , certain cancers ²⁶ and other chronic diseases ^{1 , 2,27} . The presence of antioxidant compounds in vegetables and fruits could play a role in this protection.

What does asparagus contain?

Phenolics
The asparagus contains more phenolic compounds , the main ones of flavonoids (rutin mainly) and phenolic acids (including hydroxycinnamic acid). These compounds have antioxidant properties , that is, they reduce the damage caused by free radicals in the body. The latter are very reactive molecules which are implicated in the appearance of cardiovascular diseases, certain cancers and other diseases linked to aging ^{34 , 35} .

The green and purple asparagus contain more phenolic compounds than white asparagus ^{5 , 28} . The act of peeling the asparagus would not seem to influence its phenolic content when fresh, but would reduce by against its content in phenolic compounds when peeled before being stored ²⁸ .

Asparagus is said to have better quality antioxidants in greater quantity than many vegetables commonly consumed in Europe and the United States ^{3 , 4} , such as yellow onion, red onion, garlic, broccoli and pepper . But its consumption is relatively reduced. From a health point of view, an increase in the consumption of asparagus would therefore be welcome.

Carotenoids
Asparagus contains carotenoid pigments , mainly beta-carotene, lutein, zeaxanthin and capsanthin ⁷ . As the asparagus matures, the concentrations of lutein and beta-carotene tend to decrease, while the amounts of zeaxanthin and capsanthin increase. The carotenoids are compounds with antioxidant properties and consumption of foods rich in carotenoids is linked to a lower risk of developing certain cancers ^{6 , 29} and cardiovascular disease .

Thiols
Among some fifteen vegetables, asparagus ranks ^1st  for its content in two types of thiols, glutathione and acetylcysteine ¹⁰ . These compounds have different antioxidant properties ⁹ . Among other things, glutathione could improve the elimination of oxidized cholesterol, which is very damaging to the arteries. Eating foods rich in glutathione could also lower the risk of cancers of the upper digestive tract . ¹¹ As these results are not related to the specific ingestion of asparagus, more studies will have to be carried out in order to know the effect of the consumption of thiols of this vegetable.

Saponins
Asparagus contains saponin, mainly protodioscin ¹² . In addition to contributing to the antioxidant activity of asparagus, this saponin is also known for its toxic effects in vitro on certain human cancer cells ^{13 , 14} . This effect has not been evaluated on the consumption of asparagus, but researchers have observed that the lower part (base) of this vegetable contains up to 100 times more protodioscin than the upper part (tip) ¹² . As the base of asparagus is usually cut before consumption, the beneficial effects of this compound are most often lost.

Phytoestrogens
Asparagus contains small amounts of isoflavones and lignans, two types of phytoestrogens ¹⁵ . These compounds, whose structure is similar to estrogens, could reduce the risk of certain cancers ^16-18. It should be noted that the isoflavone content of asparagus is considerably lower than that of soy products (approximately 200 times less isoflavones than tofu and 90 times less than soy milk). However, the quantity of lignans present in asparagus is generally equal to or higher than that of soy products. In addition, cooking asparagus would not have a major impact on their concentration of phytoestrogens. Asparagus could therefore help increase the food intake of phytoestrogens.

Fructo-oligosaccharides
Fructo-oligosaccharides (FOS) or oligofructoses are a type of carbohydrate naturally present in certain vegetables and fruits such as asparagus, onion, chicory, artichoke, garlic and bananas ^{32 , 33} . Fructo-oligosaccharides are known for their health benefits, especially for their prebiotic effect , their favorable effect on the absorption of minerals, as well as the reduction of cholesterol, triacylglycerols and blood phospholipids.

Sulfur compounds
A sulfur compound called dimer has been detected in some vegetables, including asparagus ⁸ . This molecule has recently shown antioxidant properties and has been found in human urine and plasma. These results are promising and more research is needed to better understand the effect of this compound in humans.

Main vitamins and minerals

Precautions

Vitamin K and anticoagulants
The asparagus contains high amounts of vitamin K. This vitamin, required among other blood clotting, can be manufactured by the body and more to be in certain foods. People taking anticoagulant drugs (Coumadin ^® , Warfilone ^® , Sintrom ^® , etc.) should eat a diet with relatively stable vitamin K content from day to day. Asparagus is part of a list of foods that should be eaten at most 1 time per day. The recommended serving is 250 ml (1 cup) each time. People on anticoagulant therapy are strongly advised to consult a dietitian-nutritionist or a doctor in order to know the food sources of vitamin K and to ensure a daily intake as stable as possible.

Preparation

To access other recipes, you can go to the CuisineAZ.com kitchen recipe site, which offers, among other things, the following recipes: asparagus mousse, asparagus soup, asparagus soup

If fresh, green and purple asparagus does not need to be peeled. By cons, it is imperative to peel the white . To remove the rigid part, hold the body of the asparagus with one hand and the foot with the other, and fold. The break will take place where the asparagus is no longer edible because it is too tough.

There are commercially available pans specially designed for asparagus: tall and narrow, they allow them to be cooked vertically, leaving the tips, which cook faster than the rest, out of the water.

• Flemish style. Boiled, serve with half a hard boiled egg and melted butter. The yolk of the egg is crushed with a fork, seasoned and mounted in butter on the plate by the guest himself.

• Boiled or steamed . It takes 3 to 5 minutes for green ones and, depending on their diameter, 8 to 12 minutes for white ones.
• Floods . With a yogurt-based dip, present them nicely by serving greens, whites and violets.
• Roasted. You can simply brush them with oil and spicy salt or marinate them in a sauce made with olive oil, balsamic vinegar, a little maple syrup and mustard seeds. Then grill them in the oven or on the barbecue (5 to 7 minutes, in either case).
• With a Mornay or Hollandaise sauce .
• With grated Parmesan cheese . Brown in the oven and add a knob of butter before serving.
• With a green sauce made of yogurt and herbs.
• With a sauce prepared with butter, orange juice and zest , salt and pepper.
• Chinese-style sauté. Cook the cut pieces in lengths of 1 to 2 cm for 3 to 5 minutes in hot oil, stirring constantly. Or, sauté them with shiitake mushrooms and peas. Add orange juice and cook until the vegetables are tender. Serve over lettuce with orange wedges and toasted pecans.
• In an omelet , after blanching them for 5 minutes.
• In the form of soup , velouté or consumed .
• As a dip . Cook them first, then pass them through a blender with sour cream, onion, garlic and salt.
• As a garnish on canapes. Serve tender tips that can be beaten with cream or yogurt.
• In ice cream or candied in a sugar syrup and garnished with an orange or lemon mousse.

To choose

Contrary to popular belief, fine asparagus is less tender than large asparagus , because it is proportionally richer in wood fiber. Choose asparagus with tightly closed and compact tips . You can find purple asparagus on the market. However, cooking causes them to lose their color.

Keep

The longer you keep the asparagus before consuming it, the more fibrous it will be, especially at room temperature. Their sugars quickly transform into starch and the formation of woody tissue is accelerated.

Fridge. First wrap the base of the bunch of paper towels and put everything in a plastic bag. Or, place them vertically in a jar containing 5 cm of water. They will keep for 1 or 2 weeks.

Freezer. Once blanched for 3 minutes in boiling water, the asparagus will keep for about 8 months. Cook them without thawing them.

Asparagus is a plant whose claw produces buds that lengthen each year in fleshy stems called turions . It takes its name from the Latin asparagus which itself borrowed it from the Greek asparagos , which comes from Persia. The word ”  asparagus  ” appeared in French in 1256. Until the XVII ^th  century, also wrote “asparge”.

It is believed that asparagus comes from the east of the Mediterranean basin and from Asia Minor. The Romans would have domesticated it 200 years before our era. The Greeks would have preferred to pick it in the wild, convinced that it made a much better remedy. Indeed, it enjoyed a very high reputation as a medicinal plant . It was supposed to cure everything from the stings of bees to the heart trouble through the dropsy and toothache . It was also considered an aphrodisiac and for that reason we did not hesitate to drink the water in which it had cooked. Anyway, are undeniable, as any consumer of asparagus can attest …

Asparagus is one of the plants ‘exotic’ than the Italian princess Catherine de Medici brought in his luggage when in the XVI ^th  century, it crosses the Alps to marry the future king of France, Henry II. A century later, Louis XIV granted his first gardener a title and a piece of land to thank him for having found a way to grow this precious vegetable all year round. At the same time, French gardeners developed the technique for obtaining white spears. The method consists in buttering them (covering their base with soil as they grow) so as to deprive them of the sun and thus prevent them from making chlorophyll. This technique will pass in Germany and in other countries of Europe, but it will never be completely adopted in North America, where one prefers by far the green asparagus to its cousin pale.

Universally appreciated, asparagus has been integrated into all cuisines, both oriental and western. However, it remains relatively expensive, because unlike many other vegetables, it must be harvested by hand .

Asparagus prefers sandy soil , but will be satisfied with all soils provided they are well drained. She hates having wet feet, the main cause of claw rot.

pH  : 6.5 to 7.5. Avoid planting where it is less than 6.

You can multiply the asparagus from seeds or 1-year-old claws . In the first case, sowing is done indoors 10 or 12 weeks before the last frost. Young plants or claws will be placed in the ground when the soil temperature reaches 10 ° C. You should think about installing them north or west of the vegetable garden, because the plant, which easily rises to 2 m, provides a lot of shade.

Dig a groove 10 to 15 cm deep, add a good layer of manure or compost, place the young plant or claw in it and cover with soil. Provide a spacing of 45 cm in the row and 1.5 m between the rows. The spears will emerge a few weeks later. It will refrain from harvesting the 1 ^st  year, and it will reap that for three weeks the second year, to allow the plant to nutrient reserves. Its longevity (at least 15 years) and its productivity depend on compliance with this rule. For the same reasons, from the 3 ^rd yearlings will only be harvested for 6 to 8 weeks each spring, and the foliage will not be pruned until late fall or early spring.

Irrigation

The first 2 years, it is necessary to water well if the weather is dry. Subsequently, water once or twice during the harvest period and a few times during the summer, when the foliage forms. Finally, a few good waterings in the fall will increase production the following year and protect the plants from damage caused by frost during the winter.

Harvest and care

The shoots are harvested preferably in the morning, when they are 15 to 25 cm long and their tips are still tightly closed. You can either cut them a few centimeters below ground level with a knife, or break them by hand . As long as the harvest period lasts, collect all spears, regardless of their quality. This prevents early foliage formation and delays the arrival of the beetle , an insect that feeds on it and weakens the plant. Harvesting is normally stopped when the diameter of three quarters of the spears is no more than 1 cm or less. At this point, collect all the spears one last time, add a good layer of compost and mulch abundantly to counteract the emergence of weeds. Every spring, add a layer of compost or decomposed manure and, in the fall, a 10 to 12 cm mulch, which you will remove the following spring.

A mature plant will produce 15 to 20 turions per year. To meet the fresh asparagus needs of a family of 4, it is estimated that 12 to 18 plants are needed.

Diseases and insects

In the family vegetable garden, pests and diseases are rare. Most problems will be prevented by taking care to respect the recommended spacing between plants and rows, to drain the soil well, to have good air circulation between plants and to water and fertilize plants well. In case of rust attack , treat with sulfur. To avoid Fusarium wilt , against which there is no treatment, it must be ensured that the original seeds or plants are not contaminated. To do this, do business with a renowned seed producer or nurseryman. The new “Jersey” varieties, which only produce male plants, would be more resistant than the traditional varieties.