Evaluation of grain nutritional quality and resistant starch content in Kenyan bread wheat varieties

Micronutrient deficiency is a major problem worldwide, particularly in developing countries that rely heavily on cereal rich diets for sustenance. Wheat ( Triticum aestivum L .), a popular staple cereal crop contains substantial levels of  micronutrients, thus could be used for alleviating dietary micronutrient deficiencies. The objective of this study was to evaluate the effect of wheat genotype and selected agro-ecological zones on kernel accumulation of zinc, iron, resistant starch and phytic acid. In whole meal flour prepared from nine Kenyan bread wheat  varieties, Zn and Fe levels ranged from 111 to 305 μg g -1 , and 26 to 91 μg g -1 . Phytic acid and resistant starch levels ranged from 2.66 to 5.05 μg g -1 and 0.37 to 6.00 g 100 g -1 , respectively across three sites. Variety × site influenced iron and resistant starch content significantly (Pu003c0.05), whereas zinc and phytic acid were influenced by variety and interaction. Njoro BWII variety had the highest Zn and phytic acid levels; while Fe and resistant starch were obtained on K. Korongo and K. Tai varieties, respectively. Overall, Eldoret site had optimal conditions that enhanced accumulation of preferred nutrition values. In conclusion, whole meal flour prepared from all 9 varieties contained considerable levels zinc, iron, resistant starch and low levels of the undesirable phytic acid. Key Words : Iron, phytic acid, Triticum aestivum, zinc La deficience en micronutrients est un probleme majeur de par le monde, surtout dans les pays en voie de developpement, qui dependent fortement de mets a base de cereales. Le ble ( Triticum aestivum L. ), un aliment de base cerealier tres populaire, contient un taux tres eleve de micronutrients, il peut ainsi etre utilise pour corriger les regimes alimentaires carents en micronutriments. L’objectif de l’etude etait d’evaluer l’effet des genotypes de ble et de zones agro ecologiques ciblees sur l’accumulation de zinc, fer, amidon resistant, et acide phytique dans les grains de ble. Les teneurs en zinc et en fer des des repas a base de ble entier prepares a partir des varietes de ble Kenyan variaient de 111 a 305 μg g -1 , et 26 a 91 μg g -1 . Les teneurs en acide phytique et en amidon resistant allaient de 2,66 to 5,05 μg g-1et 0,37 a 6,00 g 100 g -1 , respectivement dans trois sites  d’experimentation. L’interaction variety-site d’experimentation a influence les teneurs en fer et en amidon resistant de facon significative (Pu003c0.05), tandis que les teneurs en zinc et en acide phytique ont ete influencees par la variete et  l’interaction. La variete Njoro BWII avait la teneur en zinc et en acide phytique la plus elevee, tandis que fer et amidon resistant avaient ete respectivement obtenus avec les varietes K. Korongo et K. Tai . Au total, le site de Eldoret presentait les conditions optimales qui favorise l’accumulation des nutriments preferes. Il convient de conclure que des repas entiers  prepares a partir de 9 varietes de ble Kenyan contenaient des niveaux considerables de zinc, fer, amidon et de faibles niveaux d’acide phytique non desirable. Mots Cles : Fer, acide phytique, Triticum aestivum, zinc