Researchers enhance the versatility of sweet potato

WITH keeping fit and eating healthily being the “buzzwords” today, the University of Pretoria has found a way to make the humble sweet potato last even longer in order to address micro-nutrient deficiencies among young children and pregnant women.

Sweet potatoes are reportedly high in fibre and antioxidants, which protect the body from free radical damage and promote a healthy gut and brain.

They’re also rich in beta-carotene, which is converted to vitamin A to support good vision and boost the immune system.

With all those benefits in mind, researchers at the University of Pretoria have found a way to make orangefleshed sweet potato last longer as part of InnoFoodAfrica, a multinational, cross-continental project that aims to enhance food and nutrition security in Africa.

These potatoes have a shelf life of between two and three weeks The researchers discovered that they could extend the health benefits of the vegetable by making it into longer-lasting flour.

In addition, by turning the potatoes into flour, researchers have found they could also expand the number of ways in which they could be used.

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Kgonothi, who is central to the development of the flour and has been working under the guidance of Professor Naushad Emmambux and Dr Nwabisa Mehlomakulu of the Department of Consumer and Food Sciences at the institution, explained they had experimented with drying the sweet potatoes using various methods.

Kgonothi said since the vegetable was a perishable product, drying and milling the potatoes into flour was one of the best methods one could apply, giving it a shelf life of at least a year.

He said the process began with the team sourcing sweet potatoes from a commercial farm in North West, following a four-to-six-month growth period, from planting to harvesting.

As it is a seasonal crop which is planted around November or December, the harvest takes place between March and June or July.

Following that, Kgonothi said the team set about testing different drying methods.

“The whole process took about three weeks, which included testing the drying process and doing the actual drying and milling. We used microwaves, infra-red applications and convection ovens to dry the potatoes and discovered that when we combined microwave drying with infrared, drying the process was much faster. There was also higher retention of beta-carotene.”

With vitamin A deficiency being one of the leading causes of micro-nutrient deficiencies in children up to the age of 6 and pregnant women, Kgonothi said flour made from orangefleshed sweet potato could offer a helpful solution.

“The flour is also a good source of dietary fibre and of minerals such as iron, zinc and phosphorus. As flour, the application of orange-fleshed sweet potatoes is more diverse as the flour can be used in baked products like fortified bread or biscuits or as stabilisers in soups; due to its rich dietary fibre.

“As a bonus, because of its low viscosity, it can be used to make baby food, making it easy for infants to swallow,” he added.