Yacon: What a sweet deal

JANE WRIGGLESWORTH
Last updated 10:26 13/03/2014
Southland Times photo
Fairfax NZ
Yacon flowers resemble tiny sunflowers, to which they are related.

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Can the sweet-tasting syrup from the yacon root really help you lose weight? That's the claim of some. But you know what they say. If it's too good to be true, it probably is.

This South American vegetable has been getting a lot of press lately. Yacon syrup, which is dark in colour and has the same consistency as golden syrup, contains fructooligosaccharides, sugar molecules which pass right through the digestive system, and inulin, a dietary fibre that also passes through the digestive system unmetabolised.

The syrup does contain small amounts of digestible sugars - sucrose, fructose and glucose - but as most of it contains fructooligosaccharides and inulin, the calorie intake is much less than normal sugar. Apparently, the syrup - or more specifically the fructooligosaccharides and inulin it contains - can also help promote weight loss and improve glucose regulation in overweight adults.

Much more research needs to be done in this area, but the yacon plant (Smallanthus sonchifolius) can be grown in your own backyard as a tasty, low- glycemic vegetable. The perennial tubers look a lot like kumara, grow a bit like jerusalem artichoke and taste like a cross between carrots and apples. They are moist and crunchy inside, the reason they're called yakon in the first place. Yakon in the Inca language means "water root".

The tubers can be eaten raw, like a fruit, or roasted, stir-fried, chipped or juiced. They can be chopped and added to fruit salads, though drizzle them with lemon juice first to stop the flesh from oxidising.

Grown in the Andes, they are traditionally eaten in the field by workers as a moist refreshment. The leaves are also used to wrap food when cooking, much like grapevine leaves are used when cooking dolmades.

Yacon has been grown in South America for centuries but it came to New Zealand only in 1982.

A member of the sunflower family, yacon plants produce small sunflower- like blooms (just like jerusalem artichokes, which are also in the same family) on stalks up to 2.5m high, in late autumn.

The tubers form underground, each held together in a clump. Mature tubers can reach 25cm long and 10cm in diameter. The tubers are harvested after flowering when the top growth dies back, around May or June, or six to eight months after planting.

Just like potatoes, the plants are susceptible to frosts, so they need to be grown in a frost-free spot or in tunnel houses in cooler areas.

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Typically you'll buy crowns and plant these out from about September to November, though where frosts are absent you can plant them any time of the year. Plant in cool spots and if you buy crowns that already have leaves, these can be planted out a bit later than if planting bare crowns.

Plants will grow in most soils, even poor ones, though if given a deep, rich, organic soil in full sun, they'll thrive. Dig in plenty of compost before planting, then plant the crowns at least 50cm apart. Cover with soil and then mulch. You will need to provide good moisture in dry spells. If water is lacking, yield will be affected. Keep the area weeded, too, so that there is no competition for moisture.

In cooler areas, a mulch of straw from mid autumn will help protect the tubers if a sudden frost should occur. The leaves may die back but the tubers should be protected.

When the plants flower, this is the time commercial growers would harvest and process the roots, as fructooligosaccharide levels are at their highest. Though home gardeners don't have to - the tubers can remain in the ground and dug as needed, providing the soil is free- draining. In their first year, the tubers may be small, but in subsequent years they will double or triple in size.

When it comes to harvesting, dig out the tubers carefully. Yacon plants, like jerusalem artichokes, will grow from any piece of crown left in the ground. Though thankfully, as these are clump- forming perennials, they stay in one localised area.

Remove the tubers from the crown and store them in a cool, dark and dry place, with good air circulation where they will keep for months.

To store the crowns, cut the stems back to about 10cm and place the stem with the crowns still attached in damp sand or sawdust in a cool, frost-free place until spring. New plants do not grow from the tubers but the crowns. Keep the sand damp, not wet. To increase your plants, divide the tubers in early spring and pot them up. Plant them out when the risk of frosts has passed. About the same time you plant your tomatoes is a good time to plant your yacon tubers.

Keep up the watering and you'll have another good yield the following year.

- The Southland Times

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