Table of Contents
ISSN: 2672-4499
Vol. 6(1), pp. 29-37, 2026
Copyright ©2026, the copyright of this article is retained by the author(s)
https://gjournals.org/GTFSN
DOI Link: https://doi.org/10.15580/gtfsn.2026.1.042726061
Department of Microbiology, Federal University Wukari, PMB 1020 , Taraba State, Nigeria
Type: Research
Full Text: PDF, PHP, HTML, EPUB, MP3
DOI: 10.15580/gtfsn.2026.1.042726061
Accepted: 29/04/2026
Published: 15/05/2026
*Corresponding Author
Obasi, Blessing Chidi
E-mail: obasibc@fuwukari.edu.ng
Keywords: microbial safety, fermentation, Ogi, sprouted and unsprouted Sorghum
Microbial characterization of Ogi is essential to distinguish beneficial fermenters from harmful contaminants, especially when comparing sprouted and unsprouted sorghum. Traditional Ogi fermentation is spontaneous and governed by naturally occurring microorganisms. The study evaluated the microbiological quality of Ogi produced from fermented sprouted and unsprouted white sorghum grains. Three samples were analysed: sprouted (SPS1), unsprouted (USPS2), and a control sample (CTS), microbial isolates were identified using standard methods. A progressive decline in pH was observed during fermentation, with SPS1 showing the most pronounced reduction from 6.51 to 3.60 after 72 hours, indicating lactic acid fermentation. Total aerobic plate counts ranged from 2.5 × 10³ to 2.2 × 10⁵ CFU/mL. Coliforms were detected only in SPS1 at 3.0 × 10² CFU/mL, while USPS2 and CTS showed no detectable coliform growth. Yeast counts ranged from 4.8 × 10⁵ to 3.2 × 10⁶ CFU/mL, The higher yeast population observed in CTS and SPS1 reflects the availability of fermentable substrates that favor yeast proliferation, while the absence in USPS2 suggests reduced fermentative activity. Lactic acid bacteria counts ranged from 7.6 × 10⁵ to 1.7 × 10⁶ CFU/mL. The dominance of Lactobacillus in SPS1 demonstrated enhanced lactic acid fermentation associated with sprouting, which contributes to acid production, microbial stability, and improved safety of the Ogi. Predominant microorganisms identified included Lactobacillus plantarum, Pediococcus pentosaceus, Saccharomyces cerevisiae, Candida albican, Enterobacter spp and Escherichia coli. The result indicated that sprouting and fermentation significantly improve microbial safety, making sprouted sorghum Ogi more suitable for infant feeding and potential industrial applications.
Fermented cereal foods play a critical role in African diets, particularly in West Africa where sorghum (Sorghum bicolor) is widely cultivated and consumed. It is ranked the fifth among world food grain the annual world production is over 60 million tons, of which Africa produces about 20 million tons. About 45 million hectares of sorghum are cultivated in the world and USA is the number one producer followed by Nigeria. Sorghum is a good source of energy, proteins, carbohydrates, vitamins and minerals including the trace elements, particularly iron and zinc, except calcium. Sorghum grain contains minerals such as phosphorus, potassium and magnesium in varying quantities (Ogodo et al., 2019). Traditional treatments such as soaking, cooking, germinating and fermenting have been used to improve nutritional quality of the sorghum.
Fermentation increases the starch and protein digestion of the most important sorghum-based fermented foods. Ogi ,is a traditional sour porridge produced from maize, millet, or sorghum. It remains a major weaning food and breakfast meal due to its affordability, digestibility, cultural acceptance, and nutritional benefits (Adebiyi et al., 2022). Sorghum is valued for its resilience to drought and poor soils, making it an essential raw material for traditional foods. Fermentation is a key processing step in Ogi production and involves steeping, milling, sieving, and spontaneous fermentation. This fermentation process is driven mainly by lactic acid bacteria (LAB) and yeasts, which enhance food safety, improve sensory properties, and increase nutrient bioavailability (Mokoena, 2020). Lactic acid bacteria (LAB) such as Lactobacillus plantarum and Pediococcus spp. produce lactic acid and antimicrobial metabolites that suppress spoilage organisms, while yeasts contribute to aroma and flavor development.
Sprouting (malting) is another traditional technique used to improve cereal quality. It increases enzymatic activity, enhances vitamin content, improves mineral bioavailability, and reduces anti-nutritional factors. However, sprouting also alters the microbial ecology, potentially influencing the safety and quality of Ogi (Rodríguez-Pérez et al., 2021). Comparing sprouted and unsprouted sorghum Ogi is therefore essential to determine the safest and nutritionally superior method. Given the popularity of Ogi among infants and vulnerable populations, microbial quality is a major concern. Studies have shown that traditional cereal fermentations may contain both beneficial fermenters and undesirable contaminants such as Escherichia coli or Staphylococcus aureus when hygiene is poor (Tamang et al., 2020).
. Despite the nutritional and cultural significance of Ogi, its traditional preparation is largely artisanal and depends on spontaneous fermentation, which may lead to inconsistent microbial profiles. Inadequate hygiene practices can result in contamination by pathogenic microorganisms, posing risks to consumers, especially infants who rely on Ogi as a primary weaning food (Omemu et al., 2020). Additionally, sprouting is known to enhance nutrient bioavailability, little research has compared the microbial quality of sprouted versus unsprouted sorghum Ogi, particularly in Nigeria. This creates a gap in knowledge on how sprouting affects microbial diversity and potential safety. Therefore, this study is aimed at evaluation of the microbiological quality of Ogi produced from fermented sprouted and unsprouted sorghum grains by isolating and characterizing microorganisms present, which is crucial for ensuring food safety, and supporting potential industrial applications.
Healthy white sorghum (Sorghum bicolor) grains were purchased from Wukari main market, Taraba State, Nigeria. The purchased sorghum were transported under hygienic conditions to the Microbiological Laboratory, Federal University Wukari, for processing and analyses.
Comparative experimental design was used to evaluate the effect of sprouting on the microbiological quality of Ogi produced from white sorghum. The experiment consisted of two treatments: sprouted Ogi (SPS1) and unsprouted Ogi (USPS2), with a control sample (CTS) included for comparison. All treatments were prepared and analysed in duplicate.
The Sorghum grains were carefully selected by removing stones, dirt’s and broken kernel. A total of one thousand, one hundred and fifty grams (1250g) of clean white sorghum grains were washed with sterile water and divided into two equal portions, 625 g each for Sprouted and Unsprouted Ogi production.
Sprouting (malting) was carried out following the method of Adelekan et al. (2022) with slight modifications .Six hundred and twenty five grams (625g) of the grains were steeped in 500 mL of sterile distilled water for 24 hours at room temperature (28 ± 2 °C), with the water being changed every 12 hours to reduce microbial contamination. After steeping, the grains were spread on moistened jute sacks, covered with a damp muslin cloth, and allowed to germinate for 72 hours under dark, humid conditions. The sprouted grains were then washed thoroughly, oven-dried at 50 °C for 12 hours, and stored in sterile containers prior to Ogi preparation.
The second 625 g portion of cleaned white sorghum grains was steeped directly in 500 mL of sterile water for 48 hours at room temperature (28 ± 2 °C),water being changed after 24 hours.
Figure 1.1: Process flow chart for the preparation of Unsprouted and sprouted ogi
Source: (Omemu et al., 2020).
Plate:1 Unsprouted Sorghum
Plate:2 Sprouted Sorghum
2.4 Production of Ogi from Sprouted and Unsprouted Sorghum
Ogi production process was carried out using the traditional method as described by Okoye and Onyekwere (2021): Steeped (sprouted and Unsprouted) grains were wet-milled into a fine paste using a sterile blending machine, the paste was mixed with sterile water and sieved through a muslin cloth to separate the starch slurry from bran and filtrate was left undisturbed to sediment at room temperature in sterile containers. After that the water was decanted and the samples used for analyses.
Plate 3: Samples of Ogi sprouted, unsprouted and control.
2.5 .1 Preparation of Media
Culture media were prepared in accordance with the manufacturer’s instructions. The culture media were Nuutrient Agar 2.8g, MacConkey Agar 5.5g, 1.5g of Peptone water, Potato Dextrose Agar 3.9g and de Man Rogosa Agar 3.3g was weighed and dissolved in 100mL each of peptone water and sterilized by autoclaving at 121⁰c for 15minutes Pounds per Square Inch (PSI)
2.5 .2. Enumeration and Isolation
Total bacterial count was determined using the method as described by (Obasi et al., 2019). The stock solution was prepared by dissolving 1g of the of Ogi samples in 9mL of sterile Peptone water, serial dilution (10 fold) were carried out (1:10,1:100,1:1000…10,000). 1.0 mL of appropriate dilution (10–² and 10–⁴) was plated on various Agar plates using pour plate method and incubated at 37⁰c for 18—24hours for total bacteria, coliform and lactobacillus. Fungi was incubated at room temperature (28 ± 2 °C) for 72hours. The actual number of bacterial and fungi count was calculated as colony-forming unit (CFU/g)
2.5.3. Purification and Maintenance of Microbial Isolates
Microbial isolates obtained from the fermented Ogi samples, including sprouted, unsprouted, and control samples, were purified to obtain pure cultures. Purification was carried out using the streak plate method on appropriate selective and differential media. Nutrient agar was used for general bacterial isolates, De Man, Rogosa and Sharpe (MRS) agar was used for lactic acid bacteria, Sabouraud Dextrose Agar (SDA) was used for yeast and mold isolates, and MacConkey agar was used for the isolation of coliform bacteria. Individual colonies exhibiting distinct morphological characteristics were carefully selected and re-streaked onto fresh agar plates.
2.5.4 Identification and Characterization of Microbial Isolates
The Identification and characterization of microbial isolates obtained from fermented Ogi samples were carried out based on morphological, microscopic, and biochemical tests following standard microbiological procedures (Martin, 2022; Hafezi and Khamar, 2024).
2.5.5. Colony Morphology
Growth features on plates as observed on Nutrient Aga, MacConkey Agar, de Man Rogosa Agar and potato Dextrose Agar are shown below:
Plate: 4. de Man Rogosa Agar (MRS)
plate. Plate: 5. Potato Dextrose Agar (PDA)
Plate.6 MacConkey Agar plate
Plate: 7. Nutrient Agar plate
2.5.6 Biochemical Tests
Plates with growth features on the bacterial isolates subjected to biochemical tests such as:, Oxidase, Methyl Red Voges–Proskauer (MRVP), and Triple Sugar Iron (TSI) agar tests following standard microbiological identification protocols are shown below:
Plate: 8. Oxidase test
Plate: 9. Methyl Red Voges–Proskauer (MRVP) test
Plate: 10. Triple sugar ion test (TSI)
Data obtained from the samples were statistically analyzed using the Statistical Package for Social Sciences (SPSS), version 17.0. Data were subjected to analysis of variance (ANOVA) to determine significant differences among the samples. Duncan’s Multiple Range Test (DMRT) was used to separate the means at p < 0.05.
Table 3.1 shows the aerobic plate count of bacterial cells, coliforms, fungi (yeasts), and Lactobacillus (CFU/g) of fermented Ogi samples produced from sprouted (SPS1), unsprouted (USPS2), and control (CTS) white sorghum grains.
Total aerobic bacterial Count: The total aerobic bacterial count ranged from 2.5 × 10³ CFU/g (CTS) to 2.2 × 105 CFU/g (SPS1), while no detectable growth (ND) was observed in USPS2. The higher bacterial load in SPS1 indicates that sprouting enhanced nutrient availability, thereby supporting increased microbial growth during fermentation, whereas the absence of growth in USPS2 suggests limited microbial activity.
Coliform count: Coliform counts ranged from not detected (USPS2 and CTS) to 3.0 × 10² CFU/g (SPS1). The very low coliform presence in SPS1 suggests minimal contamination, while the absence in USPS2 and CTS indicates improved hygienic quality and the inhibitory effect of fermentation acids on coliform survival.
Fungal (Yeast) count: Yeast counts ranged from not detected (USPS2) to 4.8 × 105 CFU/g (CTS), with SPS1 showing 3.2 × 106 CFU/g. The higher yeast population observed in CTS and SPS1 reflects the availability of fermentable substrates that favor yeast proliferation, while the absence in USPS2 suggests reduced fermentative activity.
Lactobacillus count: Lactobacillus counts ranged from not detected (USPS2) to 1.7 × 106 CFU/mL (SPS1), with CTS recording 7.6 × 105 CFU/g. The dominance of Lactobacillus in SPS1 demonstrates enhanced lactic acid fermentation associated with sprouting, which contributes to acid production, microbial stability, and improved safety of the Ogi.
Table 3.1: Total aerobic plate count of bacterial cells, coliforms, Lactobacillus and yeast count (CFU/g) from Sprouted and unsprouted ogi produced from white sorghum grains
Sample code
SPS1
USPS2
Key: ND= not detected
The result in Fig.1.2 shows the microbial isolates identity from fermented sprouted (SPS1), unsprouted (USPS2), and control (CTS) Ogi samples. Based on the observed characteristics, the isolates were presumptively identified as Enterobacter spp, Micrococcus spp. and Staphylococcus spp., organisms commonly associated with fermented cereal foods and processing environments.
The unsprouted Ogi (USPS2) sample showed greater microbial diversity compared to the sprouted sample. These included Bacillus spp. Escherichia coli. Isolates obtained from the control (CTS) Enterobacter aerogenes, Lactic acid bacteria were isolated from all samples sprouted, unsprouted and control (SPS1, USPS2, and CTS). Lactobacillus plantarum and Pediococcus pentosaceus, which are known to play a significant role in cereal fermentation by producing organic acids that enhance product safety, shelf stability, and sensory quality.
Fig 1.2: Prevalence of Microorganisms Isolated from Fermented Ogi Samples (SPS1, UPS2 and CTS)
The dominance of lactic acid bacteria in SPS1 is consistent with Mokoena (2020), who identified LAB as the principal microorganisms responsible for acid production, pathogen inhibition, and overall safety of fermented cereal foods. This observation also agrees with Achi and Asamudo (2021), who reported that traditional Nigerian fermentations are characterized by LAB-dominated ecosystems that enhance preservation and nutritional value. The detection of yeasts alongside LAB aligns with Teniola and Odunfa (2019), who found that yeasts coexist with LAB in cereal fermentations and contribute to flavour development and fermentation efficiency.
The higher occurrence of opportunistic organisms in USPS2 supports the findings of Nwachukwu and Odu (2020), who reported that inadequate fermentation permits survival of contaminating bacteria due to insufficient acidification. Likewise, Lau et al. (2021) emphasized that failure to achieve rapid pH reduction in fermented foods increases the risk of Enterobacteriaceae contamination, which explains the poorer microbial quality of USPS2. Furthermore, the improved microbial safety observed in SPS1 agrees with Akinyemi and Jimoh (2023), who demonstrated that sprouting combined with fermentation enhances LAB dominance and suppresses undesirable microorganisms in sorghum Ogi.
The synergistic improvement observed when sprouting was combined with fermentation in this study is in alignment with Adebo and Njobeh (2022), who concluded that germination followed by fermentation significantly enhances microbial safety, and functional properties of African cereal foods. Similarly, Jideani et al. (2021) highlighted that such processing strategies are essential for improving the nutritional quality of cereal-based complementary foods in developing countries, reinforcing the relevance of SPS1 as a superior product.
The sprouted sample (SPS1) exhibited improved quality attributes such as faster acidification, higher lactic acid bacteria (LAB) counts, and better fermentation performance. In contrast, the unsprouted sample (USPS2) showed relatively higher pH and lower fermentation efficiency. The combination of sprouting and fermentation enhanced microbial quality, making sprouted sorghum Ogi more suitable for infant feeding and potential commercial application.
There is no conflict of interest, all authors agree to the subject.
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