Yacon is an easy-to-grow Food Plant with Multiple Uses

A rare and most special addition to your food forest, yacón (pronounced yah-cone)  actually looks more like an ornamental that belongs in the back of a flower bed. For it has lush, velvety tropical foliage and copious small flowers. It is hard to find in South Africa, but could not be easier to grow.

Besides, it is becoming very trendy as a functional health food. It is also known as the Peruvian Earth apple.

Botanically is is Smallanthus sonchifolius,and its usefulness as a dietary component of South Africans  qualifies it as an “orphan species”, one which, according to University of Pretoria horticulturust Jason Sampson, deserves more attention as a modern addition to the diet in South Africa.

Native American food plant

Another amazing example of Native American people’s mastery of plant domestication, this relative of the common sunflower and dahlia is planted along drainage lines and next to fields as part of the landscape until needed a season or ten seasons later.

Grown in South America, this native of the Andes produces huge, water filled roots that have something of the flavor and texture of a pear, or apple, and are considered convenient refreshment to field workers who will dig the roots while working, rather than trudge down the mountainside to collect water.

Indeed, the roots are considered fruit analogs, and are sold as such in indigenous markets, hence the name “Earth apple”.

Sweetener

Where modern interest in the crop lies is that it is remarkably low in calories, as the sweet principle is a long chain molecule that the human body treats as a soluble roughage, and does not digest.

These fructooligosaccharides (FOS) are, in other words, an entirely natural, non-nutritive sweetener, and yacón syrup can be easily prepared from liquidised roots, strained and concentrated. This syrup is about a half as sweet as sugar, and is very expensive in South Africa as it is all imported.

Roots sweeten when “cured” out of the ground for a few weeks, and whole storage roots will store roughly as long as potatoes.

Health teas

There are other uses for this food plant, such as health teas prepared from the leaves, but the storage root is the main crop, and the reason the plant has been of such interest to agronomy in recent years.

Popularised by research in Japan starting in the late 1990s, yacón tubers are rich in bioactive compounds beneficial for human health apart from the aforementioned FOS (the sweet principle in the root). Additionally, they contain phytoalexines, phenolic compounds and high concentrations of fructanes.

The leaves have been shown to have free radical scavenging, cytoprotective and anti-hyperglycemic activity.

Medicinal use

Generally, derivatives of yacón are investigated scientifically for medicinal use because of its antidiabetic and hypoglycaemic effects.

In Andean folk medicine, yacón is used against liver and kidney disease whereas it is used against diabetes and digestive problems in Bolivia.

How it grows

The plant grows as a clump of annual stems, which can be evergreen in mild climates but die back with cold.

There is little variation in clones available in South Africa, if you can find planting material. It is still a very rare plant. In growth the clumps grow to about 2m in height, and need about as much space in cultivation as a true sunflower.

Crown roots are white turning purple when exposed to sun, and storage roots are brown, even when cured. Other colours of root skin and flesh are grown overseas.

Cultivation

This plant is best considered a sunflower in field. It needs the same cultivation protocols in terms of space, water and pest control. It is a long season crop however, and will take a growing season to produce roughly ten kilos of storage roots per clump. Plants can also be left to grow for multiple seasons.The potential harvest is then measured in wheelbarrow loads!

Plants are propagated clonally, from crown tubers that are split into largish pieces (10cm long is ideal). They are planted immediately in early September as they begin to sprout.

Plants are hardy to most climates encountered in South Africa, but can wilt a bit in heat. Plants die back in very cold areas. Crowns should then be mulched. Watering should stop in winter if roots are left in the ground as they can rot when wet and cold during dormancy.

Seed saving and sharing

Clumps can be harvested in May/June, the storage roots removed from the crown roots. The whole crown is then stored in compost or wood shavings somewhere cool until splitting for spring planting. They may get a bit rubbery in storage, but a soak overnight in water will have them firm and ready to plant.

Roots can also be left in ground and crop and propagation material harvested in spring. However care must be taken not to water as storage roots can rot in cold, wet soil while the plants are dormant.

Crown roots travel well if wrapped in plastic, and anyone growing yacón really should try to share material with other growers. This food plant is very well adapted to cultivation in the South African climate and has a huge potential market in the health and functional food markets.

Uses and markets for this food plant

Yacón storage root can be used in cooking, including baking as a sweetener. It keeps relatively firm if cut into chunks, making it an intriguing substitute for apple in pies and similar.

As a functional food the market for yacón syrup and extracts is huge overseas and growing. The plant is currently grown in New Zealand and Japan as a crop, and interest in, and farming of, this plant is spreading to anywhere where sunflower can be grown.

The plant is remarkably easy and forgiving in cultivation, and small efforts can lead to big harvests, says Sampson, who has been growing yacón for three seasons thus far.

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For more information on this, or other orphan crops, please contact Jason Sampson at jason.sampson@up.ac.za