Orange Maize Research Articles

Linking agriculture to nutrition – The harvest is near and how do we measure impact?

An emerging success story in linking agriculture to nutrition is the biofortification of staple crops with micronutrients, namely provitamin A carotenoids, iron, and zinc. As a case study, biofortification of staple crops with provitamin A carotenoids has included sweet potato, maize, and cassava using traditional breeding methods, while transgenic approaches have been utilized in Golden Rice. Human studies have included a variety of technologies, and stable isotope methods are among the most powerful to measure bioavailability and efficacy. Animal and human studies have demonstrated promising β‐carotene to retinol bioconversion factors. Long‐term intake studies in children have been completed or are underway to determine if these favorable bioconversion factors can translate into improved liver reserves of vitamin A. Using the naturally enriched, stable 13C‐signature of maize, the change in 13C‐enrichment in serum retinol was shifted in 3 to 5 year old children eating orange maize for 70 days. This shows that the β‐carotene is bioavailable and contributing to the vitamin A pool. Another study is evaluating changes in total body stores of vitamin A after 90 days of feeding orange maize to 5 to 7 year old children using the 13C2‐retinol isotope dilution test. Effectiveness studies after biofortified maize is broadly introduced are needed to investigate the feeding of β‐carotene enhanced staple crops to population groups. Biofortification of staple crops with provitamin A carotenoids is feasible and all results published to date point towards it being an effective method to improve long‐term vitamin A status of populations that adopt them.Supported by NIH‐5T32DK007665–20 and HarvestPlus

Genetic Analysis of Visually Scored Orange Kernel Color in Maize

Increasing levels of provitamin A carotenoids in maize (Zea mays L.) grain through plant breeding has potential to help humans suffering from vitamin A deficiency. In parts of Africa where this deficiency is prevalent, there is a consumer preference for white maize grain and an avoidance of yellow maize grain. White grain has minimal levels of carotenoids whereas yellow grain can have appreciable levels of carotenoids. There is a new effort to introduce orange maize that contains high levels of provitamin A, which appears to be a more acceptable color than yellow to consumers in Africa. The implementation of this program requires backcross selection to convert African‐adapted germplasm with white grain to orange. We conducted a study to assess the heritability of visual scores for relative intensity of orange kernel color and identify genetic markers associated with orange color across and within 10 families of the maize nested association mapping population. We found visually scored kernel color to have a moderately high heritability and identified five common quantitative trait loci (QTL) and six rare QTL for intensity of orange color. Notably, half of them coincided with carotenoid biosynthetic genes. Our results indicate that breeders in Africa, Asia, and throughout the world would have flexibility to select for orange kernel color visually and/or with gene‐specific markers. Such selection can be combined with marker‐assisted selection efforts to increase provitamin A levels in maize grain.

Comparative Intake of White- versus Orange-Colored Maize by Zambian Children in the Context of Promotion of Biofortified Maize

Vitamin A deficiency is associated with poor health outcomes related to reproduction, growth, vision, and immunity. Biofortification of staple crops is a novel strategy for combating vitamin A deficiency in high-risk populations where staple food intakes are high. African populations are proposed beneficiaries of maize (Zea mays) biofortified with provitamin A carotenoids, often called "orange maize" because of its distinctive deep yellow-orange kernels. The color facilitates ready recognition but presents a cultural challenge to maize-consuming populations, including those in much of Africa, who traditionally eat white varieties. This study explores the intake patterns of, as well as adaptation to, traditional foods made with provitamin A-biofortified maize compared with white maize in rural Zambian children 3 to 5 years of age (n = 189) during a 3-month feeding trial. The subjects were fed a breakfast of maize porridge (sweet mush), a lunch of maize nshima (stiff mush) with various side dishes, and an afternoon snack based on a 6-day rotating menu. The trial was conducted in 2010. The orange maize used in the trial came from three different sources. O1 maize was from the 2009 harvest and was stored in a freezer until use in 2010. O2 maize was also from the 2009 harvest and was stored in a cold room until 2010. O3 ("fresh") maize was from the 2010 harvest and was fed immediately after harvest in week 9 of the study and then stored in a freezer until milling for the final four weeks. Consumption of menu items, except snacks, was influenced by week (p < .0084). The intakes of porridge and nshima made with orange maize equaled those of porridge and nshima made with white maize from week 2 onward. The intakes of porridge and nshima prepared from O1 and O2 did not differ, but intakes became significantly higher when meals made from O3 were introduced (p < .014 for porridge and p < or = .013 for nshima). These results demonstrate quick adaptation to orange maize, a preference for recently harvested maize, and an optimistic outlook for similar adaptation patterns in other biofortified-maize target countries.

Using a discrete choice experiment to elicit the demand for a nutritious food: Willingness-to-pay for orange maize in rural Zambia

Using a discrete choice experiment, this paper estimates the willingness to pay for biofortified orange maize in rural Zambia. The study design has five treatment arms, which enable an analysis of the impact of nutrition information, comparing the use of simulated radio versus community leaders in transmitting the nutrition message, on willingness to pay, and to account for possible novelty effects in the magnitude of premiums or discounts. The estimation strategy also takes into account lexicographic preferences of a subset of our respondents. The results suggest that (a) orange maize is not confused with yellow maize, and has the potential to compete with white maize in the absence of a nutrition campaign, (b) there is a premium for orange maize with nutrition information, and (c) different modes of nutritional message dissemination have the same impact on consumer acceptance.

Adaptation to and Intake Patterns of Traditional Foods Made from Biofortified Orange Maize (Zea mays) in Rural Zambia Children

Vitamin A deficiency (VAD) persistently plagues much of the world, propagating poor health outcomes related to reproduction, growth, sight, and immunity. Biofortification of staple crops is a novel strategy for combating VAD in high‐risk groups. Many African populations are proposed beneficiaries for provitamin‐A biofortified maize (Zea mays), often called “orange maize” due to distinct yellow/orange kernels. Its color challenges cultural acceptance by maize‐consuming communities that traditionally eat white varieties. This study explores adaptation to, and intake patterns of, traditional foods made with orange maize compared with white in rural Zambian children (n = 189) during a 3‐mo intervention. Subjects were fed maize porridge breakfast, maize nshima with relish lunch, and snack. Consumption of menu items, except snacks, increased significantly by week (P&lt;0.0084). Orange porridge and nshima intakes equaled white from week 2 onward. During the trial, 3 orange maize meals were fed: 2009 freezer (O1), 2009 cold room (O2), 2010 fresh (O3). Subjects consumed uniform amounts of porridge and nshima prepared from O1 and O2, but intakes became significantly higher after O3 maize meal substitution (P&lt;0.014 porridge; P&lt;0.013 nshima). Results demonstrate quick adaptation to orange maize, preference for fresh, and an optimistic outlook for similar adaption patterns in other orange‐maize target countries.Grant Funding Source: HarvestPlus 8217

Carotenoid-Biofortified Maize Maintains Adequate Vitamin A Status in Mongolian Gerbils

Efforts to biofortify maize with provitamin A carotenoids have been successful, but the impact on vitamin A (VA) status has not been determined. We conducted two studies that investigated the bioefficacy of provitamin A carotenoids from maize and compared maize percentage and carotenoid concentrations on VA status in VA-depleted Mongolian gerbils (Meriones unguiculatus). Gerbils (n = 40/study) were fed a white maize diet 4 wk prior to treatment. In study 1, treatments (n = 10/group) included oil control, 60% high-β-carotene maize, and β-carotene or VA supplements (matched to high-β-carotene maize). In study 2, gerbils were fed 30 or 60% orange or yellow maize diets. Gerbils were killed after 4 wk. In study 1, liver VA concentrations, compared with the high-β-carotene maize group (0.25 ± 0.15 μmol/g), were higher in the VA group (0.56 ± 0.15 μmol/g, P < 0.05), lower in the control (0.10 ± 0.04 μmol/g, P < 0.05), and did not differ in the β-carotene group (0.25 ± 0.08 μmol/g). Bioconversion was ∼3 μg β-carotene to 1 μg retinol (1.5 mol β-carotene to 1 mol retinol). The liver β-carotene content was greater in the high-β-carotene maize group (26.4 ± 6.0 nmol) than in the β-carotene supplement group (14.1 ± 6.0 nmol; P < 0.05). In study 2, the gerbils’ VA status improved with increasing dietary β-carotene. Liver VA in gerbils fed orange maize was greater than in those fed yellow maize, regardless of maize percentage (P < 0.05). Biofortified maize adequately maintained VA status in Mongolian gerbils and was as efficacious as β-carotene supplementation. In populations consuming maize as a staple food, using orange instead of white maize could dramatically affect VA status.

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The effect of different feeds in comparison with that of maize grains on the egg yolk color was observed. It was found that deep orange and yellow orange maize give satisfactory coloration to the yolk, respectively orange and yellow. The most intense color was observed when green feed was used in combination with deep orange maize. Green feeds as chicory, alfafa, cabbage, welsh onion and banana leaves and alfafa or chicory meal proved to be good in giving orange color to the yolk. Yellow yolk was obtained when Guinea grass or carica fruit were used in the ration. Carrot and beet without leaves did not give satisfactory color to the egg yolk. The observations with other feeds are being continued.