DETERMINATION OF THE NUTRITIONAL PROFILES OF SELECTED MAIZE (Zea mays) VARIETIES GROWN IN KIRINYAGA COUNTY KENYA

Abstract

Maize (Zea mays ) is a staple food in Kenya and plays a critical role in addressing food security and nutrition. Previous research has focused mainly on yield, and drought and disease tolerance there’s however, limited comprehensive data available on the nutritional composition of different maize varieties which poses a potential for micro￾nutrient deficiency. This study aimed to determine and compare the nutritional profiles of selected maize varieties grown across the five sub counties in Kirinyaga county.Twenty-five maize grain samples collected from demonstration farms to represent selected commercial varieties were analyzed. Fourier Transform Infrared (FTIR) and Atomic Absorption Spectroscopy (AAS) techniques to determine their nutritional profiles. FTIR provided valuable information on the macro-nutrient content. Absorbance intensities at wavenumbers 997 cm-1-C-O stretch 1076 cm-1-C-O-Cstretch 1149 cm-1-C-O-C- asymmetric stretching attributable to carbohydrates, 2854 cm-1-CH₂ symmetric stretching 2925 cm-1 asymmetric stretching 1743 cm-1-C=0 stretching 1709 cm-1-C=O stretching attributed to fatty acids and fatty acid esters and, 1539 cm-1 amide ii -N-H bending/-C-N stretching 1646 cm-1amide i C=O Stretching of peptide bonds linked to proteins were obtained to represent relative nutritional content in the samples. Principle component analysis and heatmaps was used to analyze the data collected from the spectra. FTIR-PCA which accounted for 95.53% of the variability showed clustering in terms of variety. Heatmaps revealed that KE-7 had consistently higher absorbance intensities across the measured wavenumbers. AAS was used to quantify essential micro-nutrients (Fe, Mg, Mn and Zn). Results showed that magnesium was the most abundant mineral with a mean concentration of 1254.14mg/kg, zinc ranked second with a mean concentration of 43.27 mg/kg, iron had a mean concentration of 41.38 mg/kg while manganese had a mean concentration of 5.90 mg/kg. Significant regional differences were observed for the elements measured with Mwea east and west showing generally higher mineral concentrations. By employing FTIR, AAS and PCA this research provided a rapid, cost-effective, and accurate method for assessing the nutritional composition of maize varieties. The findings will contribute to enhancing our understanding of the nutrient content variation across different maize varieties in Kirinyaga, Kenya and guide agricultural practices, and dietary recommendations