A Study of the Impact of Maize Domestication on Its Chemical Composition and Bioactive Properties

Maize, also known as corn, is a major staple crop globally, contributing as a significant source of food, feed, and industrial products. It is a key cereal crop in human diets, especially in regions like the Americas, Africa, and Asia, providing for nearly 30% of food calories to more than 4.5 billion people. Breeders have performed selective breeding over the years to turn maize from its wild ancestor, teosinte, into its modern variety (Zea mays). While its yield has increased, some health-beneficial compounds may be lost in the process. Most of the previous studies were aimed at understanding the genotypic changes underlying this process of domestication. Hence, this thesis aims to study the potential phenotypic changes in maize varieties caused by domestication. This study aimed firstly to identify the changes in the chemical composition of maize due to domestication, and secondly, to study the potential antioxidant and anti-inflammatory properties of different maize varieties. This study involved 76 varieties of maize, viz., 26 varieties of modern maize (MM), 25 varieties of landraces (L), and 25 varieties of teosinte (T). Results concluded that teosinte kernels have different bioactive metabolites acting as potential antioxidant precursors, whereas modern maize and landraces have an abundance of sugars. It was also observed that teosinte kernels have thrice the average protein content compared to modern maize and landrace kernels. Upon simulated gastrointestinal digestion, it was found that teosinte lines have higher peptide content compared to modern maize and landraces, but a lesser degree of hydrolysis of proteins than the other two groups. It was observed that digested teosinte lines are rich in peptides with hydrophobic and charged amino acid residues, indicating potential antioxidant and anti-inflammatory properties. This was further validated through in-vitro cellular models, where most teosinte lines showed higher antioxidative and anti-inflammatory potential. This validated our hypothesis that there has been a loss of potential bioactive compounds during domestication. This research paves the way for understanding the functional changes in maize varieties corresponding to genetic variations, thereby helping to improve the nutritional value and yield of maize in the future. Advisors: Kaustav Majumder and Toshihiro Obata