Bioactive Composition and Free Radical Scavenging Activity of Fresh Orange Maize Hybrids: Impacts of Genotype, Maturity Stages, and Processing Methods

Emmanuel Oladeji Alamu; Bussie Maziya-Dixon; Abebe Menkir; Emmanuel Anyachukwu Irondi; Olorunfemi Olaofe

doi:10.3389/fnut.2021.640563

Bioactive Composition and Free Radical Scavenging Activity of Fresh Orange Maize Hybrids: Impacts of Genotype, Maturity Stages, and Processing Methods

Front Nutr. 2021 Feb 24:8:640563. doi: 10.3389/fnut.2021.640563. eCollection 2021.

Authors

Emmanuel Oladeji Alamu^{1

2}, Bussie Maziya-Dixon², Abebe Menkir³, Emmanuel Anyachukwu Irondi⁴, Olorunfemi Olaofe⁵

Affiliations

¹ International Institute of Tropical Agriculture, Southern Africa Research and Administration Hub (SARAH) Campus, Lusaka, Zambia.
² Food and Nutrition Sciences Laboratory, International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria.
³ Maize Breeding Unit, International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria.
⁴ Department of Medical Biochemistry and Pharmacology Kwara State University, Ilorin, Nigeria.
⁵ Department of Chemistry, Ekiti State University, Ado Ekiti, Nigeria.

Abstract

Bioactive compounds in foods are responsible for their biological activities, but biotic and abiotic factors may influence their levels. This study evaluated the impact of three genotypes (designated 4, 5, and 7), maturity stages (20, 27, and 34 days after pollination) and processing methods (hydrothermal and dry-heating) on the bioactive constituents (carotenoids, phytate, tannins, vitamin C) and 2,2-diphenyl-2-picrylhydrazyl radical (DPPH^*) scavenging activity of fresh orange maize hybrids. Freshly harvested maize cobs of each genotype were subjected to hydrothermal processing at 100°C and dry-heating with husks and without husks. Carotenoids (lutein, zeaxanthin, β-cryptoxanthin, α-carotene, and total β-carotene) contents of fresh and processed samples were analyzed using HPLC; other bioactive constituents and DPPH^* scavenging ability were determined using spectrophotometric methods. Genotype had a significant effect on the levels of carotenoids (p < 0.001) and vitamin C (p < 0.05), while genotype (p < 0.001), and processing methods (p < 0.001) had significant effects on DPPH^* SC₅₀. Maturity stages, processing methods and their interaction also had significant effects (p < 0.001) on the levels of all the bioactive constituents. A positive moderate to strong correlation was observed between (p < 0.001) α-carotene and the following: lutein (r = 0.57), β-cryptoxanthin (r = 0.69), total β-carotene (r = 0.62). However, the relationship between α-carotene and zeaxanthin was positive but weak (r = 0.39). A positive moderate correlation (p < 0.001) was observed between lutein and the following: β-cryptoxanthin (r = 0.57), total β-carotene (r = 0.58), and zeaxanthin (r = 0.52). A positive strong correlation (p < 0.001) was observed between β-cryptoxanthin and each of total β-carotene (r = 0.92) and zeaxanthin (r = 0.63); total β-carotene and zeaxanthin (r = 0.65); while the association between vitamin C and DPPH^* SC₅₀ was negative and weak (r = -0.38). Generally, genotype 4 and harvesting at 34 days after pollination had the best combination of bioactive constituents and DPPH^* scavenging ability.

Keywords: Dehusking; bioactive constituents; free radicals; hybrids; maize husks; maturity stages; orange maize; processing methods.