Aldo Rosales

Maize (Zea mays L.) landraces are rich sources of genetic and nutritional diversity, yet their compositional traits remain undercharacterized compared to modern hybrids. This study compiled and analyzed data from 1554 maize samples—995 landraces and 559 hybrids—evaluated at the CIMMYT Maize Quality Laboratory over more than a decade. Traits assessed included kernel structure, macronutrients, iron, zinc, carotenoids, and anthocyanins. Landraces showed greater variability and higher average concentrations of protein (10.88 vs. 9.92%), iron (17.63 vs. 13.91 mg kg⁻¹), zinc (22.70 vs. 18.98 mg kg⁻¹), and anthocyanins, whereas hybrids, particularly those developed through provitamin A biofortification programs, exhibited higher average provitamin A (3.33 vs. 1.84 µg g⁻¹) and total carotenoid concentrations. Correlations between kernel structural components and nutrient composition highlighted the structural basis of grain quality variation. These findings demonstrate that landraces and hybrids provide complementary nutritional profiles that can jointly support breeding, food innovation, and sustainable food systems.

Los cereales son la principal fuente de calorías en la dieta humana. Durante su almacenamiento, las condiciones ambientales inducen el enranciamiento, especialmente en harinas integrales. Programas de mejoramiento de cereales los monitorean mediante indicadores de rancidez para identificar aquellos con una mayor vida de anaquel. El índice de peróxido es uno de estos indicadores, pero la cantidad de grano disponible para analizar usualmente es limitada y las cantidades de aceite extraído son inferiores a 0.5 g y no existe método aplicable con esta limitación. Se modificaron los parámetros y sistema de extracción de metodologías existentes y se validaron los resultados obtenidos. El método desarrollado es sensible y preciso para cantidades iguales o menores a 0.5 g de aceite extraído.

Zinc deficiency poses a significant health challenge worldwide, particularly in regions where access to and the affordability of dietary diversity are limited. This research article presents a time course analysis of kernel development on the zinc content in maize kernels with different genetic backgrounds, including normal maize, quality protein maize, and high-zinc maize, grown at two locations. Zn concentrations during stage I were high, decreasing between stages II and IV and increasing during stages V to VII. High-zinc kernel genotypes, including those ones with high-quality protein genetic backgrounds, have higher contents of zinc and iron during the milky stage (fresh/green maize). The zinc and iron content in fresh maize differed depending on the genotype. By consuming fresh maize biofortified with zinc, up to 89% and 100% of EAR needs can be fulfilled for pregnant women and children. The results demonstrate that fresh high-zinc maize accumulates a substantial amount of this micronutrient, highlighting its potential as a valuable source for addressing zinc deficiency.

Vitamin A deficiency (VAD) is a public health issue worldwide. Provitamin A (PVA) biofortified maize serves as an alternative to help combat VAD. Breeding efforts to develop maize varieties with high PVA carotenoid content combine molecular and phenotypic selection strategies. The phenotypic assessment of carotenoids is currently done using liquid chromatography, a precise but time- and resource-consuming methodology. Using near-infrared spectroscopy (NIRS) could increase the breeding efficiency. This study used ultra-performance liquid chromatography (UPLC) data from 1857 tropical maize genotypes as a training set and NIRS data to do an independent test of a set of 650 genotypes to predict PVA carotenoids using Bayesian and modified partial least square (MPLS) regression models. Both regression methods produced similar prediction accuracies for the total carotenoids (r² = 0.75), lutein (r² = 0.55), zeaxanthin (r²= 0.61), β-carotene (r² = 0.22) and β-cryptoxanthin (BCX) (r² = 0.57). These results demonstrate that Bayesian and MPLS regression of BCX on NIRS data can be used to predict BCX content, the current focus on PVA enhancement, and thus offers opportunities for high-throughput phenotyping at a low cost, especially in the early stages of PVA maize breeding pipeline when many genotypes must be screened.

Provitamin A (proVA) enhanced maize was developed to help alleviate vitamin A deficiency in maize-consuming populations. Nixtamalization (lime-cooking process) is the most commonly used maize-preparation method in Mexico and Central America. In this study, the effect of traditional nixtamalization (TN) and nixtamalized extrusion (NE) on proVA retention was evaluated. Kernel conversion to TN dough led to high proVA apparent retention (>100%), while kernel conversion to NE flour led to lower retention (85%). However, TN tortilla proVA carotenoid concentration was similar to the kernels’ original concentration and slightly higher in NE tortillas. Genotypic variation has a strong effect on proVA retention in TN dough and NE flour, but no such variation in proVA retention was observed in tortillas. Tortillas prepared with proVA-enhanced maize, using either TN or NE, are a good source of proVA carotenoids. Also, dough made using TN and proVA-enhanced maize is a high proVA-content ingredient for other food products.