Amazing maize

2011-10-17 00:00

A TEAM of scientists on the Pietermaritzburg campus of the University of KwaZulu-Natal have bred a vitamin-A rich strain of maize which could have a major impact on health on the African continent and beyond.

“We responded to a global call to improve the nutritional status in one of the biggest staple foods consumed all over Africa,” says John Derera, Plant Breeding, African Centre for Crop Improvement.

The call came from HarvestPlus, an international challenge programme, seeking to reduce hunger and provide micronutrients to billions of people through the foods that they eat. According to their website they “use a novel process called biofortification to breed higher levels of micronutrients directly into key staple foods”.

HarvestPlus had already identified the 10 best strains of vitamin A-fortified maize in 2003. “We didn’t want to work below the bar,” says Derera, who conducted the breeding programme, “so we asked for the best 10 and began working with them.”

The provitamin A-biofortified maize was bred to be higher in vitamin A than white maize using conventional plant- breeding techniques to create hybrids. These are not genetically modified plants.

“We wanted to find the appropriate vehicle for people to get vitamin A through something they like to eat and that is culturally acceptable as well as affordable,” says Frederick Veldman, head of dietetics and human nutrition.

Early in the breeding programme, Derera connected with Kirthee Pillay and Muthulisi Siwela, both of the dietetics and human nutrition department, to create a larger project that, as well as the plant breeding, would study the nutritional composition of the maize produced, the vitamin-A retention after milling and cooking, and the possible consumer acceptance.

The nutritional composition fell within an acceptable margin. “There was a high level of nutrients compared with white maize,” says Pillay. “The total vitamin content was between 7,3 and 8,3 micrograms per gram dry weight. With white maize the vitamin content is zero.”

HarvestPlus has declared 15 micrograms per gram dry weight as the target and the team will continue aiming for this but in the meantime they have produced a hybrid that delivers a substantial amount of vitamin A.

“It will be another two to three years before we can realise the HarvestPlus target,” says Derera, “but we already have a marketable product and we have potential partners in the private sector.”

Vitamin retention has also been impressive. “Provitamin A was found to be well retained after the maize was milled,” says Pillay, “and there was over 90% retention after cooking — making such traditional South African foods such as phutu, thin porridge and samp.”

Vitamin A is essential to maintain good health and especially for healthy development in children. “Vitamin-A deficiency seriously affects eyesight, cognitive power, and weakens the immune system,” says Siwela. “It’s a major problem in developing countries and its consequences affect national economies.”

In 1994, a national survey done by the South African Vitamin A Consultative Group (SAVACG) for the Department of Health found that 33% of children — that’s one in three — under the age of six years were deficient in vitamin A. As a result of this finding, the government implemented food fortification which involved the sale of vitamin A-fortified bread and maize products plus a vitamin-A supplementation programme providing vitamin-A supplementation to children aged six to 59 months and women in the postpartum period.

Despite these initiatives, the 2005 National Food Consumption Survey — Fortification Baseline (NFCS-FB) — found the figures for vitamin-A deficiency in children had risen to an alarming 64%. One reason the strategy is thought not to have worked is that the fortified products were produced commercially and only available in shops. Not everyone could afford them nor were they obtainable by people living in the rural areas, those already most affected by vitamin deficiency.

Similarly, the vitamin-A supplementation programme has been unable to reach the most vulnerable target groups.

Consequently, the production of a vitamin A-enriched variety of maize which can be grown in rural areas is of vital importance. “We see this project as complementing the national strategies,” says Pillay.

The provitamin A-biofortified maize is a distinctive yellow-orange in colour due to the high level of carotenoid pigments in the plants. The best known carotenoid is carotene, the one found in carrots and responsible for their orange colour.

The colour is problematic. “White maize is seen as superior,” says Derera. “Yellow-orange maize is found on the market as an animal product. It’s used for animal feed, it’s not a food product. So eating it is associated with poverty. There is a stigma attached to it.”

According to Siwela, the yellow-orange maize also has a stronger flavour and aroma. “Whereas the white maize is somewhat bland.”

Consumer response testing was done among rural communities in the Mkhambathini municipality. “We accessed local indigenous knowledge,” says Derera. “We used local recipes and invited people from the community to prepare the food.”

“We wanted to produce the typical food that they would normally eat,” says Siwela. The same dishes — phutu, thin porridge and samp — were also made with white maize and served for comparison purposes. The foods were tested on 212 people in all, from preschoolers to those aged 55.

“We found that the preschoolers definitely preferred the yellow-orange maize,” says Pillay. “But the older school children and the adults preferred the white.

“The older groups were already sensitised to issues around the colour, whereas the younger children were not. They seem to have liked the bright colour, flavour and aroma of the yellow-orange maize.”

The team was undeterred by the findings as preschoolers are the most vulnerable group when it comes to vitamin-A deficiency and, according to Pillay, this reinforces the case for it to be used in school feeding programmes. “Another factor in the findings is that we did not conduct nutritional education. If there is education perhaps these perceptions will change.”

A study will be commissioned to find out if education changes consumer acceptance, “especially that of mothers who could use it as a weaning food”.

Derera says they are also trying to produce yellow-orange popcorn. “The feedback indicated people would consider yellow-orange maize in a variety of food products, so there is a need for further recipe diversification.”

Meanwhile, there is the provitamin A target of 15 micrograms per gram dry weight. “We will now be doing agronomic testing of the hybrids and then move on to seed work,” says Derera. “We will be testing for yield, for drought resistance, value for cultivation — can farmers grow it with ease in a variety of environments?”

“We envisaged it as a 10-year project,” says Derera, “and we still have three to go but already we have met 60% of the milestones.”


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