Omotade Richard Ogunremi

Fermentation plays a vital role globally, shaping traditional diets and enhancing food preservation, nutrition and flavour. With over 5,000 varieties of fermented foods globally, the microbiomes of many of these have yet to be explored, particularly with respect to those produced in some regions of Africa. To begin to address this knowledge gap, we conducted a shotgun metagenomics-based analysis of 91 fermented foods produced in Burkina Faso, Ghana, Kenya and Nigeria and compared them to a larger, global curated Food Metagenomic Database (cFMD). As for other studies of fermented food microbiomes in general, the substrate that was fermented emerged as the primary determinant of microbial beta diversity within the current African dataset and between the broader cFMD dataset. However, it was notable that the newly studied samples showed a small but statistically significant geographic signal. The African samples also displayed more alpha diversity than the global dataset, with cassava-, seed- and grain-based samples having the highest alpha diversity among the African foods. We also characterized the functional and antimicrobial profiles of all food-derived metagenome-assembled genomes (MAGs), noting the prevalence of pathways associated with carbohydrate metabolism across both African and non-African MAGs and an absence of known antimicrobial resistance genes in numerous genera. These findings not only expand our fundamental understanding of Africa’s under-studied fermented food microbiomes but also lay the foundation for starter culture development tailored to local substrates and conditions, fostering opportunities to enhance product safety, quality and scalability while retaining key characteristics associated with the original, artisanal product.

Yeasts are predominant microorganisms in cassava-based traditional fermented foods. Fufu and gari are unexplored reservoir for yeast strains that degrade cyanogenic glucosides. Yeasts were isolated from fufu and gari and screened for β-glucosidase production. High enzyme-producing isolates were evaluated for growth at 800 mg/L cyanide and 1.20% lactic acid. Probiotic and cyanide degradation potentials of isolates were determined. A total of 169 yeast isolates were obtained from samples of 9 fufu samples and 8 gari samples. Exactly, 157 isolates produced strain-specific levels of β-glucosidase. Five selected isolates, including-MOGB53, YOGB61, YOGB62, 3MOFA33 and 3YOGA45 demonstrated strain-specific growth indices (34.92-98.42%) at 800 mg/L of cyanide and 34.67 to 63.62% at 1.20% of lactic acid. The selected isolates survived at pH 3.5 (62.50-92.71%) and 0.5% bile salts (36.07-69.34%) and in simulated gastric and intestinal juices. They showed strong autoaggregation (89.10 to 99.60%). In cassava mash fermented with Wickerhamomyces anomalus YOGB62, cyanide content reduced from 40.15 mg/kg to 10.82 mg/kg and an undetectable level after 48 h and 72 h, respectively. This study revealed the occurrence of yeasts in fufu and gari that demonstrated potentials for application as probiotic starter cultures to detoxify cassava-based fermented foods.

This study investigated the effect of fermentation of soymilk with starter-culture on the physicochemical, microbiological, proximate and sensory properties of derived indigenous soy curd. The pH of starter culture-fermented (FSM) and uninoculated (USM) soymilks respectively decreased at different rates from 6.56 to 5.57 and 6.56 to 6.07 after 8 hours of fermentation. The total titratable acidity (lactic acid equivalent) of FSM sample is significantly higher (2.24 g/L) than that of USM (0.09 g/L). Greater proportions of carbohydrate (9.85±0.02%), protein (20.42±0.06%), fat (6.31±0.03%) and fiber (0.25±0.02%) were present in soy curd derived from starter culture-fermented soymilk (FSC) than in soy curd derived from uninoculated soymilk (USC). The sensory evaluation panelists preferred FSC to USC, in appearance, flavour, texture and overall acceptability. The color score was slightly higher for USC. The fermentation of soymilk with starter culture improved proximate properties and acceptability of derived soy curd. The starter culture improved the physicochemical properties of the soymilk used to produce the soy curd. Therefore, the development and use of starter culture may contribute to enhanced quality attributes of soy curd.

Exopolysaccharides (EPS) are gaining attention as natural additives in foods, pharmaceuticals, and cosmetics. However, limited research exists on EPS from lactic acid bacteria in traditional Nigerian fermented beverages like kunu-zaki . This study characterized the technological and functional properties of EPS produced by Weissella confusa YKDIA1 and YKDIA4 isolated from kunu-zaki . Antioxidant activities were assessed using ABTS ⁺ , FRAP, total antioxidant capacity (TAC), and DPPH assays, while hypoglycemic potential was evaluated through α-amylase and α-glucosidase inhibition. The results revealed significant antioxidant activities for YKDIA1-EPS and YKDIA4-EPS, including ABTS ⁺ (1.61 ± 0.16 mg/ml), FRAP (10.74 ± 0.36 mg AAE/g), TAC (44.19 ± 0.54 mg AAE/g), and DPPH (0.77 ± 0.04 mg/ml). YKDIA4-EPS showed superior inhibitory effects on α-amylase (0.97 ± 0.02 mg/ml) and α-glucosidase (1.25 ± 0.04 mg/ml). Both EPS exhibit antioxidative and antidiabetic activities, suggesting their potential for nutraceutical formulation. Additionally, they possess valuable physical and bioactive properties suitable for various applications. EPS from W. confusa YKDIA1 and YKDIA4 could replace synthetic antioxidants like butylated hydroxytoluene and butylated hydroxyanisole in food, cosmetic, and therapeutic products, providing a safer, natural alternative.

Pap, a gruel prepared by treatment of ogi with boiling water, is widely consumed across West Africa and in the diaspora. It is, however, unknown whether probiotic strains with multi-functional properties can survive the preparation process of pap from ogi. Thus, this study aimed to select the surviving yeasts during the preparation of pap by heat treatment of maize- and sorghum-based ogi, and to screen the yeasts for their probiotic and multi-functional attributes including in vitro mycotoxin reduction potential. Four Pichia kudriavzevii strains out of 16 yeast isolates, including Kurtzmaniella natalensis and Kurtzmaniella quercitrusa, which survived the heat treatment of ogi to form pap, passed the probiotics selection criteria. These P. kudriavzevii strains were non-haemolytic, utilized bile salt efficiently, and survived 0.3% and 0.5% bile salt concentrations, pH 2.5, gastric and intestinal conditions at 100-104% and 99-104%, 92-99%, 88-92% and 102-121%, respectively. The strains also exhibited up to 97% potential for gut colonization through adherence to hydrocarbons, auto-aggregation activities at 98-100% after 24 h, and co-aggregation of notable foodborne pathogens. In addition, the strains were tolerant to 50 °C incubation for 12 h. The strains’ intact cells and cell-free extracts revealed strong potentials to scavenge and reduce free radicals. LC-MS/MS analysis confirmed that the strains simultaneously reduced the levels of 31 mycotoxins in liquid medium in a 48-h experiment by 1-87%, which is tentatively explained through the efficient adsorption to the cell wall and subsequent metabolization. While reductions of 6-82%, 39-41% and 8-51% were observed for enniatins, sterigmatocystin and zearalenone, respectively, after incubation period of 1 h, all the other investigated mycotoxins were reduced by 1-96% at the 3-h timepoint. Probiotic P. kudriavzevii strains with multifunctional attributes are transferable to pap and other mild heat-treated products for consumer benefits.

Probiotic microorganisms are incorporated in foods due to their numerous health benefits. We investigated lactic acid bacteria (LAB) and yeasts isolated from goat milk in Nigeria for novel probiotic strains. In this study, a total of 27 LAB and 23 yeast strains were assessed for their probiotic potentials. Only six LAB strains (Weissella cibaria GM 93m3, Weissella confusa GM 92m1, Pediococcus acidilactici GM 18a, Pediococcus pentosaceus GM 23d, Lactiplantibacillus pentosus GM 102s4, Limosilactobacillus fermentum GM 30m1) and four yeast strains (Candida tropicalis 12a, C. tropicalis 33d, Diutina rugosa 53b, and D. rugosa 77a) identified using partial 16S and 26S rDNA sequencing, respectively, showed survival at pH 2.5, 0.3% bile salt, and simulated gastrointestinal conditions and possessed auto-aggregative and hydrophobic properties, thus satisfying key in vitro criteria as probiotics. All LAB strains showed coaggregation properties and antimicrobial activities against pathogens. Pediococcus pentosaceus GM 23d recorded the strongest coaggregation percentage (34–94%) against 14 pathogens, while W. cibaria GM 93m3 showed the least (6–57%) against eight of the 14 pathogens. The whole cell and extracellular extracts of LAB and yeast strains, with the exception of D. rugosa 77a, had either 2,2-diphenyl-1-picryl-hydrazyl and/or hydroxyl radical scavenging activity. In conclusion, all six LAB and four yeast strains are important probiotic candidates that can be further investigated for use as functional starter cultures.

Animal milk types in sub‐Saharan Africa (SSA) are processed into varieties of products using different traditional methods and are widely consumed by households to support nutritional intake and diet. Dairy products contain several microorganisms, their metabolites, and other chemical compounds, some with health benefits and many others considered as potential health hazards. Consumption of contaminated milk products could have serious health implications for consumers. To access the safety of milk products across SSA, studies in the region investigating the occurrences of pathogens as well as chemical compounds such as heat stable toxins and veterinary drug residues in animal milk and its products were reviewed. This is done with a holistic view in light of the emerging exposome paradigm for improving food safety and consumer health in the region. Herein, we showed that several published studies in SSA applied conventional and/or less sensitive methods in detecting microbial species and chemical contaminants. This has serious implications in food safety because the correct identity of a microbial species and accurate screening for chemical contaminants is crucial for predicting the potential human health effects that undermine the benefits from consumption of these foods. Furthermore, we highlighted gaps in determining the extent of viral and parasitic contamination of milk products across SSA as well as investigating multiple classes of chemical contaminants. Consequently, robust studies should be conducted in this regard. Also, efforts such as development cooperation projects should be initiated by all stakeholders including scientists, regulatory agencies, and policy makers to improve the dairy product chain in SSA in view of safeguarding consumer health.

Lactic acid bacteria (LAB) are important microflora in raw meat and fermented meat products. They exhibit antagonistic activities against undesirable microorganisms and are highly valued for their probiotic properties. LAB associated with raw beef from two major abattoirs in Ibadan, Nigeria were assessed for antimicrobial activity and probiotic potential. Agar-spot assay showed that 8 of 23 LAB isolates inhibited the growth of at least one of Escherichia coli, Listeria monocytogenes, K. pneumoniae and S. aureus. Selected antibacterial isolates were identified based on API50CHL as Lactobacillus plantarum (3), Pediococcus pentosaceus (2) Lactobacillus paracasei (1), Leuconostoc lactis (1) and Carnobacterium sp. (1). Antimicrobial activities were revealed to be dependent on acidification and production of bacteriocin-like substances. Five LAB strains lowered the pH of medium to < 4 within 24 h, with Leuconostoc lactis Csu12 broth culture having the lowest pH (3.04 ±0.08). Bacteriocin-like activity was displayed by six LAB strains against at least one indicator organism. The antibacterial isolates tolerated low pH and different bile concentration (0.5 and 1%). In addition, they showed different levels of hydrophobicity to xylene. Results from this study suggest the consideration of our resident LAB from meat as novel protective cultures and probiotic candidates in the food industry.