Glycyrrhiza: the liquorices

Food and medicine from the old world and the new

Liquorice (‘licorice’ in North American English) has a long history of use as a herb and was valued for giving vitality, and longevity, and as a beautifying agent and aphrodisiac. It was seen by many as an 'elixir of life' and its use appears to have been almost universal. It was used in Chinese herbal medicines dating back 5000 years and is also recorded as being used in Mesopotamia, ancient Egypt , the Roman Empire, by the Ancient Hindus and by early Buddhists.

The Liquorice of medicine and commerce is derived from the sweet root of various species of Glycyrrhiza, a genus which contains about fourteen species, natives of warmer temperate countries in both the New and Old Worlds, ten of them having roots more or less sweet, but most of them not sufficiently so to be of use.  They are legumes, nitrogen-fixing plants which like sun and a well drained site.

The use of the Liquorice plant was first learnt by the Greeks from the Scythians. Theophrastus (third century B.C.), in commenting on the taste of different roots , instances the sweet Scythian root which grows in the neighbourhood of the Lake Maeotis (Sea of Azov), and is good for asthma, dry cough and all pectoral diseases.

Dioscorides, who names the plant Glyrrhiza (Greek glukos, sweet, and riza, a root), from his description of the plant possibly had in view G.echinata, as well as G.glabra.

Currently it is grown commercially mainly in Spain and France, also the Middle East and Asia. In the early 16th Century, liquorice began to be cultivated in the monastery garden at Pontefract, England and this later became the centre of the liquorice confectionery industry.

Description

Glycyrrhiza  plants herbaceous perennials with light, spreading, pinnate foliage, presenting an almost feathery appearance from a distance. The leaflets (like those of the False Acacia) hang down during the night on each side of the midrib, though they do not meet beneath it. From the axils of the leaves spring racemes or spikes of small pale-blue, violet, yellowish-white or purplish flowers, followed by small pods somewhat resembling a partly-grown peapod in form.

The root system has two parts, one consisting of a vertical or tap root, often with several branches penetrating to a depth of 90-120 cm (3-4 ft), the other of horizontal rhizomes, or stolons, thrown off from the root below the surface of the ground, which can grow a few metres / several ft. These runners are furnished with buds and throw up stems in their second year. The perennial downward-running roots as well as the long horizontal stolons are equally preserved for use.

In the wild, liquorice is found on sandy soil near streams, usually not being  more than 50 yards from water.

The flavour of liquorice comes mainly from a sweet substance called anethole, which is also found in other plants (notably sweet cicily, Myrrhis odorata). Much of the sweetness in liquorice comes from glycyrrhizin, a compound 30 to 50 times as sweet as sucrose.

G.echinata

A native of Hungary, Italy, south Russia and Asia Minor, this grows about 1m high and has short globular heads of flowers and a small, ovoid pod with long spines. The root is also somewhat bitter and in the past it been confused with G.glabra glandulifera. Photo in flower above.

G.glabra – true/Spanish liqourice

This grows about 1m high, the pinnate leaves have 9-17 leaflets.  Flowers are purple to pale blue. In G.glabra, the pods (2.5cm / 1” long) are smooth, hence the specific name; in others they are hairy or spiny. The pods contain 1-7 small dark kidney shaped seeds about 2mm across. The development of 'runners' or horizontal stolons indicates that the root system has developed to the stage where it can be harvested.

G.glabra glandulifera – Russian liquorice

In the subspecies glandulifera (sometimes included as a separate species G.glandulifera) which grows a similar height to G.glabra, the pods are covered with thick, glandular spines, and the whole plant is pubescent or roughly glandular. The underground portion is not so spreading and produces a carrot-shaped root larger than the Spanish root derived from G.glabra. This species is indigenous to South-east Europe, Syria and Western Asia, and is both wild and cultivated in Russia. Both the Russian and Persian Liquorice of commerce is derived from G. glandulifera, the Russian is sold peeled or unpeeled: its taste although sweet, is accompanied by a more or less perceptible bitterness. It consists chiefly of roots, not runners.

Persian Liquorice root, from Iraq and Iran, is usually unpeeled, and is in rather large, coarse pieces, closely resembling the Russian root.

G.lepidota – American liquorice

This is a species of the north-western United States growing about 1m high. The rhizome resembles that of Spanish Liquorice, but is thinner. It has a long history of edible and medicinal use by the native American peoples.

G. lepidota

G.uralensis – Chinese liquorice

Originates from Turkestan, Mongolia and Siberia, similar in quality to  Russian Liquorice. Widely used in China. Widely used in Chinese medicine as well as traditional medicines of many other Asiatic coutries. Grows to 1.5m (5 ft) high.

Roots are collected spring and autumn, and often sun dried.

Cultivation

Liquorice requires a well drained (though preferably still moist) soil and full sun.

Owing to the depth to which the root penetrates and its ready propagation from detached pieces, the plant is a most persistent weed in cultivated grounds where it is indigenous and almost impossible to get rid of.

It is very healthy and robust, not susceptible to any pests or diseases.  Plants also appear to have an allelopathic effect, suppressing the growth of other plants nearby.

Commercial propagation is by seed or by cuttings from the stolons (runners).

The seed has a hard seed coat and needs to be scarified prior to sowing. Germination and early seedling growth is often slow so propagation from root cuttings is preferred.

Root cuttings 20-40 cm long with buds are used and these can be planted vertically into the soil in the dormant season, about 10cm deep. 

Grown commercially, the plantation is established with root cuttings in the early spring or late summer/early autumn with 30 cm between plants and 60 cm between rows. The land is worked deeply to provide a friable seedbed which will favour root growth. The plants make limited growth for the first two years, growing only to a height of 30 to 50 cm. Because of this slow growth, commercial growers often plant quick-growing vegetable crops between the rows of liquorice during the first two years.

The crop is ready for harvesting in the autumn of the third or (usually) fourth year. The usual practice is to carefully remove the soil between the rows, exposing the roots and runners at the sides, digging to a depth of 60+ cm (!). The whole plants are then removed and the soil placed in the trench. The roots are then washed and cut into lengths 30 to 60 cm long, sorted and graded. For commercial production, the root is sold fresh but for home use the roots can be air dried or dried artificially at a temperature of 30 to 40C. Commercial yields of fresh root machine-harvested range from 1 to 5 tonnes per hectare; formerly liquorice was habd dug to a greater depth and yields could be double this.

Fresh Liquorice when washed is externally bright yellowish brown. It is very flexible, easily cut with a knife, exhibiting a light-yellow, juicy internal substance, which consists of a thick bark surrounding a woody column. Both bark and wood are extremely tough, readily tearing into long, fibrous strings. The root has a peculiar earthy odour and a strong, characteristic, sweet taste.

Russian Liquorice grows to a larger size than the Spanish, and the taste, although sweet, is accompanied by a more or less perceptible but not strong bitterness or acridity. It consists chiefly of roots, not runners, in long often crooked pieces, about 2 inches in thickness, pale yellow externally and internally of a lighter yellow than the Spanish and softer.

Commercially, the liquorice extract is produced by fine-cutting the roots or crushing them to produce a pulp. The crushed or cut material is then boiled with water and the extract evaporated to produce either a liquid or solid form. The latter is rolled into sticks 2-3 cm in diameter and 15 cm long known as Hard Extract of Liquorice. Unfortunately, much of the liquorice sold today as strap or yard long liquorice is not pure liquorice but a processed lolly which contains other ingredients such as molasses, treacle and aniseed.

Uses

The chief constituent of true liquorice root, to which its sweet taste is due (and which has medicinal properties) is Glycyrrhizin (6 to 8 per cent), obtainable in the form of a sweet, white crystalline powder, consisting of the calcium and potassium salts of glycyrrhizic acid. Also present are sugar, starch (29 per cent), gum, protein, fat (0.8 per cent), resin, asparagin (2 to 4 per cent), a trace of tannin in the outer bark of the root, yellow colouring matter, and 0.03% of volatile oil.

The roots of G. Glabra glandulifera and G.echinata also contain in addition, glycyrmarin, a bitter compund occurring mostly in the bark.

Edible uses

Liquorice flavour is found in a wide variety of liquorice candies or sweets. In Britain and the US these are usually sweet. In most of these candies the taste is reinforced by aniseed oil, and the actual content of liquorice is very low. In continental Europe however, strong, salty candies are popular.

In the Netherlands, where liquorice candy ("drop") is one of the most popular forms of sweet, only a few of the many forms that are sold contain aniseed, although mixing it with mint, menthol or with laurel is quite popular. Mixing it with ammonium chloride is also popular, and is known as Salmiak, but mixing it with table salt creates what is probably the most popular liquorice, known in the Netherlands aszoute drop.

Pontefract in Yorkshire (UK) was the first place where liquorice mixed with sugar began to be used as a sweet in the same way it is in the modern day. Pontefract Cakes (which are more like lozenges) were originally made there.

Liquorice flavouring is also used in soft drinks, and in some herbal infusions where it provides a sweet aftertaste. The flavour is common in medicines to disguise unpleasant flavours.

Liquorice is popular in Italy (particularly in the South) and Spain in its natural form. The root of the plant is simply dug up, washed and chewed as a mouth freshener. Sticks of liquorice typically have a diameter between two and ten millimetres. Although they resemble plain wooden sticks, they are soft enough to be chewed on. These were also popular with European children in the 1950’s and 1960’s.

Throughout Italy unsweetened liquorice is consumed in the form of small black pieces made only from 100% pure liquorice extract; the taste is bitter and intense. In Calabria a popular liqueur is made from pure liquorice extract. Liquorice is also very popular in Egypt and Syria where it is sold as a drink.

Chinese cuisine uses liquorice as a culinary spice for savoury foods. It is often employed to flavour broths and foods simmered in soy sauce.

G. uralensis

Medicinal uses

Liquorice is widely used around the world as a herbal medicine. The list of complaints for which liquorice is claimed to be effective is so extensive that it appears to be a universal panacea. There are some medical conditions which are aggravated by liquorice but for normal healthy adults there is no real risk in using liquorice in moderation and its healing benefits far outweigh the risks.

The compound glycyrrhizic acid throughout Japan for the treatment and control of chronic viral hepatitis. Recent studies indicate that glycyrrhizic acid disrupts latent Kaposi’s sarcoma (as also demonstrated with other herpesvirus infections in the active stage), exhibiting a strong anti-viral effect. In China liquorice is used to treat Tuberculosis. In traditional Chinese medicine liquorice is considered an adaptogen and is commonly used in herbal formulae to relieve a spasmodic cough.

Liquorice affects the body’s endocrine system as it contains isoflavones (phytoestrogens). It might lower the amount of serum testosterone slightly, but whether it affects the amount of free testosterone is unclear.

Side effects

Moderate consumption of liquorice is not harmful.

Liquorice root contains glycyrrhizin, which can cause high blood pressure, salt and water retention, and low potassium levels; it could also lead to heart problems. Patients who take liquorice with diuretics or medicines that reduce the body’s potassium levels could induce even lower potassium levels. Taking large amounts of liquorice root could also affect cortisol (a body level’s hormone) levels as well. People with heart disease or high blood pressure and the pregnant should be cautious about taking liquorice root.

Other uses

All liquorice species are excellent bee and butterfly plants, flowering June to August.

They are all also nitrogen fixing plants.