The Functionality of “Ogi” – a fermented cereal gruel made in Nigeria, in the Management of Gastrointestinal Disease

Abstract

Fermentation is an ancient food processing technique which has over the years had significant impact on food availability, production, economy and health. Fermented corn, ‘ogi’, is a popular meal in South and West African countries and is also traditionally administered to people, especially children, during the incidence of diarrhoea as it is believed to enhance gut health. Various authors have supported the advantageous health functions of fermented corn but have focussed on the possible health benefits that may be derived from the action of the fermentation organisms by investigating their probiotic potentials. Furthermore, in vivo studies have investigated effective functionality of fermented foods and where studies have suggested positive effect of the fermented food intervention, the component of the complex food matrix that may be responsible is often unknown. Though hypothesised, there has been little information on the possible effects of the end products of the fermentation on gut health. Therefore, this thesis aimed to explore the functionality potentials for ‘ogi’, to enhance gut health by investigating the mechanisms through which it may be able to confer the health benefits when consumed. An independent meta-analysis was undertaken to explore and review the analysis of the effectiveness of fermented foods to significantly reduce the duration of diarrhoea. The first experimental study was a comparison between spontaneously fermented vs controlled method of ‘ogi’ production with the aim to explore the possibility of achieving similar end products. The probiotic potential of fermentation organisms and antimicrobial effect of fermentation organisms against E. coli were also investigated. Colonic short chain fatty acids (SCFAs) are known to enhance immune function in the gut. The second experimental study explored the production of SCFAs in fermented corn with the theory that fermented corn may be a dietary source of SCFA and may produce a comparable effect in the gut as the colonic SCFA. It is established that one of the functions of endogenously synthesised nitric oxide (NO) in the body is to enhance immune functions. Therefore, the potential for ‘ogi’ to enhance immune response in the gut by being a dietary source of Nitric Oxide (NO) was explored in the third experimental study. The outcomes of this thesis suggest that it may not be possible to mimic the exact spontaneous fermentation process in a controlled setting. Weissella confuse, Pediococcus pentosaceus and Saccharomyces cerevisiae were the lactic acid bacteria (LAB) and yeast isolated from spontaneously fermented corn using 16S rRNA sequencing. The isolated organisms along with Lactobacillus plantarum were used as starter culture for controlled fermentation. There was a significant difference between the end products of both fermentations. All organisms except W. confuse showed probiotic potential. Acetate was produced during both fermentations but butyrate was produced during spontaneous fermentation only. There was however higher concentration of NO in controlled fermented corn than spontaneous fermentation with nitrate values of 30.54 µM and 23.21 µM and nitrite values of 17.50 µM and 10.11 µM respectively. These suggest that fermented corn may have probiotic potential and may be able to further enhance immune health in the gut by being a dietary source of SCFAs and NO.