Natural Latex and Rubber From Common and Russian Dandelions

Dandelions are often considered to be annoying weeds, especially when they grow in lawns. However, some people deliberately cultivate dandelions in order to experience their nutritional and culinary benefits, and also to ensure that they aren’t treated with pesticides or exposed to pollutants and are therefore safe to eat. Researchers have discovered another very important benefit of one type of dandelion - it can be used to make rubber.

Common dandelions have bright yellow flowers that are made of many tiny florets. The dandelion’s name comes from the French phrase “dent de lion” which means "lion's tooth" and refers to the deeply divided leaves. The leaves make a nutritious and tasty salad green, or can be cooked for a hot meal. They are a good source of vitamin A (as beta carotene) and vitamin C, and are rich in potassium, calcium and iron. The flowers can be mixed with oranges, lemons, sugar, water, yeast, as well as raisins or cloves if desired, and then fermented to make a wine. They can also be dipped in a flour mixture and fried to make fritters. Dandelion roots can be cooked like a root vegetable or roasted and ground to be used as a coffee replacement.

Dandelion leaves are used as a diuretic, a substance that increases urine production and fluid removal from the body. There isn’t much scientific evidence for dandelion’s other potential health benefits, but the plant has traditionally been eaten - or drunk in the form of an infusion made from the leaves - to protect the liver.

If the flower head of a common dandelion is removed or the flower stem is broken, a milky white fluid exudes from the wound and coagulates after being exposed to air. The fluid is known as latex, and is produced by some other flowering plants as well, including the rubber tree. Most rubber today is made from the latex of the para rubber tree, but this plant's population is decreasing, along with the world's rubber supply. In several countries there are plans underway to make rubber from the latex of a relative of the common dandelion called the Russian dandelion.

A dandelion’s latex is made by specialized cells called laticifers, which form long chains inside the plant. The laticifers are perforated to form latex vessels, through which the latex travels.

Latex is a complex, sticky mixture made of polymers and other substances dispersed in water. A polymer is a long molecule made of smaller molecules joined together. The components of latex include proteins, carbohydrates, oils, resins and gums. Latex tastes bitter and contains toxic substances. It’s thought that the function of the latex in a plant’s life is to seal wounds and to protect the plant from insect attack and infection by microbes.

The scientific name of the common dandelion is Taraxacum officinale. It’s possible to make rubber from this plant, and the process is sometimes carried out as a science experiment in schools. Don’t do this experiment if you’re allergic to latex. It’s thought that since dandelions are very different plants from rubber trees it’s very unlikely that anyone with rubber latex allergies will also be allergic to dandelion latex. In fact, dandelion latex is believed to be hypoallergenic, but it's probably best to wait until this is absolutely certain if you know that you have a latex allergy.

To make the rubber, part of a finger is coated with dandelion latex. Several dandelions are needed to collect enough latex. The latex is allowed to coagulate to form rubber and is then carefully rolled off the finger. (Body heat helps the rubber to form.) The dandelion rubber is stretchy but quite delicate.

A better quality rubber is produced from Taraxacum kok-saghyz, the Russian dandelion. Some researchers say that Russian dandelion rubber is as good as the rubber produced from the para rubber tree. During the second world war the rubber supply to parts of Europe and the United States was blocked, so Russian dandelions were used to make rubber. The liquid latex needed for rubber production was hard to collect from the dandelions since it coagulated very soon after its release from the plant.

In traditional rubber production a rubber tree is wounded with a diagonal cut and the dripping latex is collected. (The tree recovers to be tapped again in the future.) The coagulation process is sped up by the addition of formic acid. The moist chunks of rubber are pressed into sheets and dried. The drying process often involves the rubber being placed in a smokehouse.

In commercial rubber production liquid latex is collected from the rubber tree and is shipped in air-tight containers to factories. Placing ammonia in the collection tanks will also prevent coagulation. In the factories the latex is shaped into sheets or placed in molds and solidified. Sulfur and heat are often used to "vulcanize" rubber. The chemical reaction between the rubber and the sulfur makes the rubber stronger and resistant to temperature changes. Without vulcanization, rubber tends to melt in hot weather and become brittle in cold weather.

Most of the South American population of the para rubber tree has been destroyed by fungus. The tree, which is also known as the Brazilian rubber tree (scientific name Hevea brasiliensis) now grows mainly in South East Asia. The Asian population is decreasing too, however, due to a combination of factors, including fungal infection, political instability, loss of habitat and possibly climate change, causing the world's natural rubber supply to decrease.

Rubber is used to form thousands of different products, but the majority is used to make tires. As the number of cars and other vehicles in the world is increasing the demand for rubber is also increasing, and it's becoming more expensive. Synthetic rubber can be produced, but vehicles require at least some natural rubber in their tires to provide elasticity, and some types of tires must be made entirely of natural rubber.

Recently researchers have once again become interested in making rubber from Russian dandelions, which look much like common dandelions but are native to Kazakhstan and Uzbekistan. The cultivation of the Russian dandelion, and perhaps other latex-producing plants, may be the solution to the world's rubber supply problem. The roots of Russian dandelion plants produce a good-quality latex.

Improved methods of latex removal are being created to tackle the problem of rapid latex coagulation after the dandelion is wounded. The latex is removed from sliced roots by chemical extraction and with a centrifuge.

Some German scientists have found a way to block the quick coagulation of Russian dandelion latex, increasing the amount of latex that can be removed. The latex coagulates when exposed to air due to the rapid production of polymers, a process called polymerization. The scientists can now stop the formation of an enzyme called polyphenoloxidase (or polyphenol oxidase) which is responsible for the polymerization. They do this by infecting the dandelion with a genetically engineered virus. The virus removes the section of genetic code in the dandelion's DNA that is responsible for the production of the polymerization enzyme. The genetically altered plants provide four to five times as much liquid latex as the plants that are not genetically altered. The researchers are breeding the altered plants and are trying to create large populations of dandelions that lack the problem segment of DNA.

Other researchers are trying to improve the yield of latex from Russian dandelions in a different way. They look for natural strains of dandelion that produce slightly more latex than other strains and then selectively breed the high-latex producers with other high-latex producers. They repeat this process in each generation of dandelion plants.

Russian dandelions are being cultivated for other reasons besides their ability to make latex. They contain a large amount of inulin, a carbohydrate that is being added to a growing number of processed foods. Inulin is a type of fiber. It isn't digested in our stomach and small intestine, but is digested by some of the helpful bacteria in the large intestine and promotes the growth of their populations. It's classified as a "prebiotic" rather than a probiotic. Probiotics contain useful bacteria; prebiotics support their growth.

Inulin is mildly sweet, yet doesn't raise the blood glucose level. This makes it useful for diabetics. It can improve the taste and texture of foods and is sometimes used as a sugar or fat substitute. Inulin also promotes calcium absorption and is used in a medical test that assesses kidney function. In addition, when inulin is fermented ethanol is produced, which can be used as a fuel. Inulin has at least one drawback, however. Eating too much inulin causes gastrointestinal upset in some people.

Most people don’t think much about dandelions, except when they’re annoyed when dandelions appear where they’re not wanted. This is a shame, because dandelions have many uses. The Russian dandelion, and possibly other types of dandelions too, may become very economically important in the next few years.