Here’s something not a lot of people realise….

There are vegetables out there posing as yams. The popular Okinawa purple yam, for example, is really a sweet potato. Sweet potatoes are often called yams, but they aren’t yams at all. The real deal yams come from the family Dioscorea – a big family, in fact, which includes a very colourful character.

Dioscorea alata is the winged yam: alata means ‘with wings’ in Latin. It’s quite well known by that name, which suits it because of the wing-like growths on its stems.

It has many other names, too. Just a few are: Guyana arrowroot; ten-months yam (because some can take that long to mature); water yam; and white yam.

And even though it can certainly come in white, or cream, its most spectacular form is the violet or bright purple variety. And that’s why, of course, it’s widely known as the purple yam. Or ube, as it is named in Southeast Asia – particularly in the Philippines, where it has been around for about 6,000 years.

Names aside, ube is an edible starchy tuber that grows above ground, on a vine (another major way it differs from the sweet potato, which grows underground). It is an important food source in many countries, but surprisingly eradicated as an invasive plant in some places (including parts of the US).

The plant probably originated in New Guinea and was introduced into Southeast Asia thousands of years ago, where it is now regularly cultivated and eaten.

The tubers often have a greyish-purple outer skin but, when cut open, reveal a strikingly vivid coloured flesh, that can range from lavender to the brightest of bright purples.

For good nutrition and health

As a source of nutrition, purple yams are a good source of all the basics. Each 100-gram serve of the cooked vegetable provides carbohydrates (27%), protein (1%), fibre (4%) and only 0.1% fat.

The same sized serving contains a huge 40% of the recommended daily amount (DV) of vitamin C, which is important for maintaining a healthy immune system and helping the body absorb iron. It also has a significant amount of potassium (13.5% DV), vitamin A (4% DV0), iron (4% DV), and calcium (2% DV), and traces of copper, folates, phosphorus and sodium.

Purple yams are low GI, which means the carbohydrates are broken down slowly before entering the blood stream, which is useful in controlling blood sugars, particularly for people at risk of type 2 diabetes.  

They also have antioxidant properties, as a result of the anthocyanin compounds that characterise foods with strong and vibrant red to purple colours. The rich purple colour of ube certainly puts it into that category. Antioxidants act in the body to protect and reduce inflammation in the cells and can be effective in lowering blood pressure.

Claims that this food is a remedy for all sorts of other ailments have to be taken with a large dose of scepticism. There is no reliable evidence that the purple yam is any more than a nutritious vegetable with some great health benefits.

And it doesn’t need to be, because it’s so delicious to eat.

A colourful and versatile food

Purple yams are among those handy vegetables that can be used in both sweet and savoury dishes.

Like potatoes, and sweet potatoes, they can be baked or boiled, and are superb when mashed with a little butter and seasoning. Sliced, or chipped, they make interesting fries – a little less crunchy than potato fries but with a more robust texture.

They keep their form really well in stir-fried, or wok-tossed dishes, but can break down easily to give added thickness and texture to soups and stews. Purple yams certainly transform any rice dish.

A layered purple yam bake, flavoured with whatever sauces and vegetables, or proteins, you prefer will make the stand-by potato bake look pale by comparison.

Purple yam flour is made by drying and pulverising the flesh. The flour gives a colour boost to baked goods. Ube cheese pandesal is a bread roll made with purple yam flour and with an oozy cheese filling. And ube-coloured macarons and cupcakes certainly stand out from the rest.

The flour is also used as a thickener in many traditional custards and cream-based desserts and adds a surprising colour depth to ice cream.

In the Philippines, the tubers are ground into a paste, which is the basis of many favourite recipes. Explore ways to make ube cheesecake, and you might never go back to the white cheese version.

Purple yam jam, halayang ube, has to be experienced to be believed. The recipe is simple: boiled and grated ube, mixed with butter, evaporated milk (or coconut milk) and a little vanilla, and then subtly sweetened with condensed milk.

Its starchy consistency is pleasant to the palate and it’s perfect on toast, bread or biscuit, or as a topping for fruit or cakes. It can be eaten all on its own, too, and is particularly good sprinkled with toasted coconut flakes, or even crystallised ginger. It can be a frozen dessert or, if the consistency is firmer, it is often set in moulds, then sliced and served like a creamy cake.

Like many foods, purple yams are sometimes tied to celebrations, particularly in the Philippines, where they are valued as part of the country’s cultural and culinary heritage – served at Christmas and birthday feasts and enjoyed at many other family occasions.

In India, during the festival of Diwali, a popular dish is ratalu nawabi. Slices of purple yam (ratalu) are fried in fragrant oil and added to a rich, hot and spicy masala mix.

And, wherever you are, if you want to add texture, a sweet nutty taste and some big colour to your cooking, the perfectly purple yam will positively fit the bill.

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