Carotenoid Retention of Biofortified Provitamin A Maize (Zea mays L.) after Zambian Traditional Methods of Milling, Cooking and Storage

Abstract

Provitamin A biofortified maize hybrids were developed to target vitamin A deficient populations in Africa. The purpose of this study was to evaluate the degradation of carotenoids after milling, cooking, and storage among biofortified varieties released in Zambia. The biofortified maize hybrids contained 7.5 to 10.3 μg/g dry weight (DW) of provitamin A as measured by β-carotene equivalents (BCE). There was virtually no degradation due to milling. The BCE retention was also high (>100%) for most genotypes when the maize was cooked into thick (nshima) and thin porridge, but showed a lower BCE retention (53-98%) when cooked into samp (dehulled kernels). Most of the degradation occurred in the first 15 days of storage of the maize as kernels and ears (BCE retention 52-56%) which then stabilized, remaining between 30% and 33% of BCE after six months of storage. In conclusion, most of the provitamin A degradation in biofortified maize hybrids occurred during storage compared with cooking and the magnitude of this effect varied among genotypes.

Micronutrient (provitamin A and iron/zinc) retention in biofortified crops

“…Similarly, 58% carotenoid retention after 6 months of grain storage for four genotypes of maize was reported by Weber et al [19]. However, Mugode et al [20] found that carotenoid degradation in three biofortified hybrids of maize cultivated in Zambia was rapid during the first two weeks of storage of the grains. The grain of biofortified maize hybrids further degraded during storage, but at a slower rate, with a final retention of 40% after six months of storage.…”

Accruing genetic gain in pro-vitamin A enrichment from harnessing diverse maize germplasm

“…Some of the promising lines had high provitamin A content by accumulating mainly higher levels of b-carotene at the expense of the synthesis of other carotenoids while others contained high provitamin A by accumulating high levels of both carotenes and xanthophylls. These lines will be useful not only for the development of hybrids and synthetics with high concentration of carotens and xanthopylls but also for elucidating the mechanisms that regulate the synthesis of more substrates upstream in the carotenoid biosynthetic pathway and the resulting increased flux downstream Table 3 Provitamin A contenet and grain yields of the best five synthetic varieties (OPV) and hybrids selected from each of the two regional trials evaluated at four to six locations in 2013, 2014 and 2015 Even though significant progress has been made in boosting provitamin A to higher levels in tropical maize, studies have demonstrated that the loss in provitamin A during storage, milling, and preparation of diverse traditional foods may reach up to 70% (Muzhingi et al 2008;Mugode et al 2014;Pillay et al 2014;De Moura et al 2015). Also, the extent of loss in provitamin A carotenoids exhibits a broad range of variation among maize genotypes in these studies.…”

Orange maize in Zambia: Crop development and delivery experience

“…A retention study conducted in Zambia showed provitamin A losses of 50% in four genotypes after 15 days of grain storage in ambient conditions, after which additional provitamin A degradation was minimal during six months of storage [14]. Beta-carotene degradation associated with traditional African household processing methods was approximately 25% for fermented and unfermented porridges [15].…”

“…Beta-carotene degradation associated with traditional African household processing methods was approximately 25% for fermented and unfermented porridges [15]. However, retention of 90-100% was observed with milled products, nshima, and porridge [14]. Overall, average retention was lower than originally assumed, particularly during storage ( Bioavailability Bioavailability of a nutrient is determined using models and, with the most promising varieties, by direct study in humans in controlled experiments.…”