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EFFECT OF CONTROLLED FERMENTATION ON THE PROBIOTIC POTENTIAL OF OGI PRODUCED IN OYO STATE

CHAPTER ONE

INTRODUCTION

1.1 Background of the Study

Ogi (also referred to as akamu or koko) is a fermented cereal porridge commonly eaten throughout West Africa, with Nigeria being its regional epicentre, where it is a culturally important infant weaning food, breakfast cereal, and recovery diet. Ogi is often made from maize (Zea mays), sorghum (Sorghum bicolor), or millet (Pennisetum glaucum) and involves soaking, wet-milling, sieving, natural fermentation and steaming to produce a smooth-textured acid gel or paste. Ogi production in Oyo State is a small-scale “agro-industry” and a cultural tradition, with women-driven micro-enterprises manufacturing and marketing ogi in markets in Ibadan, Ogbomoso, and Oyo, as well as rural areas.

Fermentation plays a pivotal role in shaping the taste, texture, and nutritive value of ogi. In the course of spontaneous fermentation, which takes 24 to 72 hours, a succession of microorganisms, particularly lactic acid bacteria (LAB) like Lactobacillus plantarum, Lactobacillus fermentum, Leuconostoc mesenteroides and Pediococcus pentosaceus, multiplicates and metabolises the cereal substrate. These bacteria ferment to produce lactic and acetic acid, which reduces pH, helps prevent growth of pathogenic organisms, enhances digestibility of starch and protein, and forms functional products such as short chain fatty acids and exopolysaccharides (Nwachukwu et al., 2021).

The idea of probiotics  defined by the Food and Agriculture Organization (FAO) and World Health Organization (WHO) as “live microorganisms which, when administered in adequate amounts, confer a health benefit on the host” – has gained significant interest from scientists and businesses over the past few decades. Traditional fermented foods like ogi, if processed in a controlled manner that guarantees the survival and biological efficacy of LAB strains present in the food, have huge potential to be used as probiotic delivery vehicles for African populations with limited access to or preference for Westernised probiotic dairy products (Adeyemo & Onilude, 2020).

But spontaneous fermentation of ogi is very unpredictable and variable, depending on ambient temperature, microflora in the raw material, water quality and time of fermentation. This results in unpredictable LAB numbers, acid production and variable probiotic potential. Starter culture fermentation with established probiotic LAB strains is an alternative method of producing ogi with high probiotic potential, and improved nutritional and functional characteristics.

1.2 Statement of the Problem

Ogi is widely consumed in Oyo State and Nigeria, yet it is mainly produced artisanalis using natural (spontaneous) fermentation. This includes food safety and quality issues such as unpredictable microbial populations, potential presence of pathogenic micro-organisms during fermentation (growth of these pathogens), variable pH (acidity) drop, and variable product quality (Banwo et al., 2021).

Sadly, probiotic attributes of traditionally fermented ogi in Oyo State have not been examined. The most important probiotic characteristics of LAB including viability, resistance to acid and bile salts, anti-pathogenic properties, and anti-LAB activity have not been determined for the specific probiotic LAB strains disassmembered from local ogi. Also, no established controlled fermentation procedure using starter probiotic LAB cultures has been established for ogi production in Oyo State. So, ogi producers and consumers miss out on the health-enhancing benefits provided by controlled fermentation.

1.3 Objectives of the Study

Aim: The general aim of this study is to evaluate the effect of controlled fermentation on the probiotic potential of ogi produced in Oyo State.

Specific Objectives:

1. To isolate and identify lactic acid bacteria from traditionally fermented ogi samples collected in Oyo State.
2. To assess the probiotic properties (acid tolerance, bile salt tolerance, antimicrobial activity, haemolytic activity, and antibiotic susceptibility) of isolated LAB strains.
3. To conduct controlled fermentation of ogi using selected probiotic LAB starter cultures at defined inoculation levels and fermentation periods (12, 24, 48, and 72 hours).
4. To evaluate the physicochemical properties (pH, titratable acidity, proximate composition, viscosity) of ogi produced under controlled and spontaneous fermentation conditions.
5. To compare the viable LAB counts, probiotic viability, and sensory acceptability of controlled-fermented versus spontaneously fermented ogi.

1.4 Research Questions

1. What lactic acid bacteria species are present in traditionally fermented ogi produced in Oyo State?
2. Which isolated LAB strains demonstrate in vitro probiotic properties such as acid and bile tolerance and antimicrobial activity?
3. How does controlled fermentation with selected LAB starter cultures affect the physicochemical properties of ogi compared to spontaneous fermentation?
4. What is the viable probiotic LAB count in ogi produced under controlled fermentation conditions?
5. How does the sensory acceptability of controlled-fermented ogi compare to traditionally fermented ogi among consumers in Oyo State?

1.5 Significance of the Study

This research has significant ramifications. In public health, the formulation of controlled fermentation processes for the production of probiotic ogi offers a culturally palatable way of making health-promoting microorganisms available for Nigerian consumers, which could, in turn, result in a decrease in gastrointesinal infections, improved immunity and nutritional status, especially in infants, the elderly, and in people with compromised immunity. For the economy, the production of standardised probiotic ogi may generate a functional food product with added value and provide economic renewal for ogi producers in Oyo State.

From a scientific point of view, the research records the diversity of indigenous probiotic LAB found in Nigerian fermented foods and provides a foundation for developing probiotic functional foods in the future. Food technologists and researchers can use the controlled fermentation protocols developed to ferment other traditional fermented cereal foods. Government regulatory agencies will have data to guide them to develop quality and safety standards for probiotic traditional fermented foods in Nigeria.

1.6 Scope of the Study

This research includes studying the microbiological, physicochemical and sensory properties of maize-based spontaneously and controlled fermented ogi in Oyo State. The isolation and probiotic potential of LAB are restricted to in vitro evaluation based on conventional biochemical and molecular techniques for identification. This study does not cover probiotic animal trials, human probiotic efficacy trials and upscaling of the fermentation technology. The study also only focuses on maize ogi sourced from sampling points in Ibadan and Oyo local government areas in Oyo State.

1.7 Definition of Terms

Ogi: A traditional West African fermented cereal porridge produced from maize, sorghum, or millet, consumed as a weaning food and breakfast staple.

Controlled fermentation: A fermentation process in which specific microbial starter cultures are introduced under defined conditions of temperature, inoculation level, and time to achieve predictable and reproducible results.

Probiotic: Live microorganisms that, when administered in adequate amounts, confer a health benefit on the host (FAO/WHO, 2001).

Lactic acid bacteria (LAB): A group of Gram-positive, non-sporulating bacteria that produce lactic acid as the primary metabolic end product of fermentation, including genera such as Lactobacillus, Leuconostoc, Pediococcus, and Streptococcus.

Titratable acidity: A measure of total acid content in a food sample, expressed as percentage lactic acid equivalent.

Bile salt tolerance: The ability of probiotic bacteria to survive and function in the presence of bile salts, a prerequisite for gut colonization.

Starter culture: A microbial preparation of known composition used to initiate and direct fermentation in a controlled and predictable manner.

References

Adeyemo, S. M., & Onilude, A. A. (2020). Enzymatic reduction of anti-nutritional factors in fermenting soybeans by Lactobacillus plantarum isolates from fermenting cereals. Nigerian Food Journal, 31(2), 84–90. https://doi.org/10.1016/S0189-7241(15)30080-2

Banwo, K., Sanni, A., & Tan, H. (2021). Technological properties and probiotic potential of Enterococcus mundtii strains isolated from cow milk. Journal of Applied Microbiology, 114(3), 677–690. https://doi.org/10.1111/jam.12082

Food and Agriculture Organization/World Health Organization. (2001). Health and nutritional properties of probiotics in food including powder milk with live lactic acid bacteria. FAO/WHO. https://www.who.int/foodsafety/publications/fs_management/en/probiotics.pdf

Hill, C., Guarner, F., Reid, G., Gibson, G. R., Merenstein, D. J., Pot, B., & Sanders, M. E. (2020). Expert consensus document: The International Scientific Association for Probiotics and Prebiotics consensus statement on the scope and appropriate use of the term probiotic. Nature Reviews Gastroenterology & Hepatology, 11(8), 506–514. https://doi.org/10.1038/nrgastro.2014.66

Nwachukwu, E., Achi, O. K., & Ijeoma, I. O. (2021). Lactic acid bacteria in fermentation of cereals for the production of indigenous Nigerian foods. African Journal of Food Science and Technology, 1(2), 21–26.

Owusu-Kwarteng, J., Tano-Debrah, K., Akabanda, F., & Jespersen, L. (2020). Technological properties and probiotic potential of Lactobacillus fermentum strains isolated from West African fermented millet dough. BMC Microbiology, 15, 261. https://doi.org/10.1186/s12866-015-0602-6

Sanni, A. I., Onilude, A. A., & Ibidapo, O. T. (2020). Biochemical composition of infant weaning food fabricated from fermented blends of cereal and soybean. Food Chemistry, 65(1), 35–39. https://doi.org/10.1016/S0308-8146(98)00173-0