Analysis of Nutrient, Fungal and Aflatoxin Compositions of Ogi Processed with Stored and Fresh Maize

Abstract

Ogi is a gruel that is widely consumed throughout Nigeria. Stored maize is often used in processing this fermented product while fresh maize is used in some cases. In this study, the incidence of fungi and aflatoxin at different stages of ogi production using stored and fresh maize was investigated. Samples of stored and fresh maize were collected from different points in the market and processed into ogi in the laboratory. Fungi were isolated at different stages of ogi production i.e. maize, steep water, and ogi samples. The incidence of each fungus was determined while their overall percentage incidence was determined at the end of production. Aflatoxin contents (AFB1, AFB2, AFG1, and AFG2) of the samples were analyzed using Thin Layer Chromatography (TLC) using AOAC procedures while their nutrient was analyzed using AOAC method. The pH and TTA of the samples were also determined. The result showed that the pH of the steep water decreased with the length of fermentation while the TTA increased. The isolated fungi include Aspergillus niger, A. tamarii, A. flavus, A. fumigatus, Penicillium chrysogenum, Penicillium sp., Fusarium sp., Rhizopus nigricans, and Saccharomyces cerevisiae. Aspergillus nigerhad the highest percentage incidence followed by Penicillium sp. and A. flavus respectively. There was a significant high content of aflatoxin in stored maize (18.48 μgkg-1) (p>0.05) compared to fresh maize (6.20 μgkg-1) with the corresponding significant higher content of aflatoxin content in stored maize ogi (2.41 μgkg-1) compared to fresh maize ogi (0.17 μgkg-1) (p>0.05). In addition, the crude protein and carbohydrate contents of fresh maize ogi (3.24 ± 0.03, 46.68 ± 0.05) were significantly higher than that of stored maize ogi (3.13 ± 0.04, 46.52 ± 0.05) (p>0.05). It was deduced that due to fungal activities in stored maize there was a reduction in the nutritional composition of its ogi sample. This study also affirms that various processing methods employed during the production of ogi had a significant effect on the reduction of aflatoxins in maize grains. Consumers are enjoined to consider the use of fresh maize in making ogi because it was found to be better for ogi production due to its higher nutritional content with lowering fungal and aflatoxin incidence. However, maize traders are advised to employ proper storage methods for storing their maize grains in order to reduce fungal and aflatoxin contamination of maize products and selling lower quality maize grains to producers of maize foods to the barest minimum thereby curbing the risk of malnutrition in infants and children.