S K Mbugua

Functional Properties of Lactobacillus plantarum Strains Isolated from Maasai Traditional Fermented Milk Products in Kenya

Lactobacillus plantarum was the major species among the lactic acid bacterial strains isolated from traditional fermented milk of the Maasai in Kenya. Selected strains were characterized for their functional properties using in vitro standard procedures. All strains expressed acid tolerance at pH 2.0 after 2-h exposure of values that ranged from 1% to 100%, while bile tolerance of acid-stressed cells at 0.3% oxgal varied from 30% to 80%. In vitro adhesion to the mucus-secreting cell line HT 29 MTX and binding capacity to extracellular protein matrices was demonstrated for several strains. The four strains tested in a simulated stomach duodenum passage survived with recovery rates ranging from 17% to 100%. Strains were intrinsically resistant to several antibiotics tested. From these in vitro studies, a number of Lb. plantarum strains isolated from the Maasai traditional fermented milk showed probiotic potential. The strains are good candidates for multifunctional starter culture development.

Use of Lactobacillus strains to start cassava fermentations for Gari production

Two Lactobacillus strains, Lactobacillus plantarum BFE 6710 and Lactobacillus fermentum BFE 6620, were used to start cassava fermentations in a pilot study under field production conditions in Kenya, to determine their potential to establish themselves as predominant lactobacilli during the fermentation. Predominant strains from three fermentations were isolated throughout the 48 h fermentation period. The use of these strains in high numbers clearly resulted in 1 to 2 log higher lactic acid bacteria (LAB) counts over the course of the fermentation when compared to the uninoculated control. 178 predominant LAB isolates were grouped based on their phenotypic characteristics, and were characterised to strain level by RAPD-PCR, followed by PFGE strain typing. Overall, L. plantarum strains represented the majority of the isolates, followed by Weissella confusa and Lactococcus garvieae strains. The results of RAPD-PCR and PFGE strain typing techniques indicated that L. plantarum BFE 6710 was successful in asserting itself as a predominant strain. In contrast, L. fermentum BFE 6620 failed to establish itself as a predominant organism in the fermentation. The success of the L. plantarum strains to predominate in the cassava fermentation demonstrates the potential for development of Lactobacillus starter cultures to industrialise the Gari production process.

The antimicrobial activity of fermented uji

Modern infant formulations based on milk have been shown to cause severe diarrhoea and malnutrition during weaning, unlike the traditional weaning foods such as uji (cereal porridge). Such diseases can be attributed to the unhygienic conditions and dirty water used during preparation of infant foods. Results on microbial growth or death of Staphylococcus aureus, Salmonella typhimurium, entero‐pathogenic Escherichia Coli and Shigella dysenteriae during uji fermentation and storage of ready‐to‐eat products are described. All the pathogens declined during uji fermentation and storage, with the declining rate being higher during storage. Invitro studies on antimicrobial activities on plates by uji culture against the pathogens, suggest that the inhibition mechanism could be due to both acid production and antibiotic substances.

Effect of drying lactic fermented uji (an East African sour porridge) on some carboxylic acids

Maize, finger millet, cassava, maize–finger millet and cassava–finger millet flours were fermented and sun-, cabinet-, or drum-dried. Total titratable acidity (TTA), fixed acidity (FA), pH and carboxylic acids were determined. The TTA of the non-fermented flours ranged from 0.22%(w/w) lactic acid in cassava to 0.36%(w/w) lactic acid in the maize–finger millet composite. After fermentation the TTA ranged from 3.26%(w/w) lactic acid in cassava–finger millet to 4.54% in maize-finger millet while FA ranged from 2.86% in cassava–finger millet to 4.26% in cassava and maize–finger millet. Fermentation decreased the pH from about 5.5 to 3.7–4.1. Drying did not change the pH but TTA decreased by 20–60%. Acetic acid levels in the fermented slurries varied from 0.80 to 0.95 µg per 5 µg while those of hexanoic acid varied from 0.9 to 1.8 µg per 5 µg. Propionic acid was absent in the fermented slurries. Acetic and formic acids were completely lost when the fermented slurries were dried. On average hexanoic acid losses on drying varied from 33% in maize to 91% in cassava fermented slurries. These losses were not significantly influenced by the drying system. In sensory evaluation panellists could not detect flavour loss as a result of drying. © 2000 Society of Chemical Industry

Effect of fermentation, malted flour treatment and drum drying on nutritional quality of Uji

Uji, a popular thin porridge in Kenya was made from sorghum flour. The uji was then either diluted 5‐fold with water and boiled, or directly drum dried for rat studies and analysis. Uji was also prepared by using a mixture of malted finger millet flour, and sorghum flour‐water slurry. The Uji was diluted 4‐fold with water and boiled or directly drum dried for rat studies and analysis. Experiments involving combinations of fermentation, malt treatment, boiling and drum drying on tannin levels were also performed. Fermentation and drum drying decreased the extractable tannins. Addition of malted flour decreased the extractable tannins much more than by fermentation and drum drying. Fermentation improved in vitro protein digestibility (IVPD) considerably. Addition of malted flour reduced IVPD as compared to control. Neither fermentation nor malted flour treatment adversely affected the amino acid profile of uji.

Strengthening capacity for sustainable livelihoods and food security through urban agriculture among HIV and AIDS affected households in Nakuru, Kenya

The promotion and support of urban agriculture (UA) has the potential to contribute to efforts to address pressing challenges of poverty, under nutrition and sustainability among vulnerable populations in the growing cities of sub-Saharan Africa (SSA). This may be especially relevant for HIV/AIDS-affected individuals in SSA whose agricultural livelihoods are severely disrupted by the devastating effects of the disease on physical productivity and nutritional well-being. This paper outlines the process involved in the conception, design and implementation of a project to strengthen technical, environmental, financial and social capacity for UA among HIV-affected households in Nakuru, Kenya. Key lessons learned are also discussed. The first has been the value of multi-stakeholder partnerships, representing a broad range of relevant experience, knowledge and perspectives in order to address the complex set of issues facing agriculture for social purposes in urban settings. A second is the key role of self-help group organizations, and the securing of institutional commitments to support farming by vulnerable persons affected by HIV-AIDS is also apparent. Finally, the usefulness of evaluative tools using mixed methods to monitor progress towards goals and identify supports and barriers to success are highlighted.

Prevalence of foodborne pathogens in food from selected African countries – A meta-analysis

Food safety information in the African region is insufficient and fragmented due to lack of surveillance, documentation and reporting, thereby resulting in inefficient utilization of resources, duplication of activities, and lack of synergy among the countries of the region. This paper reviews the prevalence of foodborne pathogens in seven African countries (Benin, Botswana, Ghana, Kenya, Nigeria, Sudan and Uganda) from papers in regional or international journals published between January 2000 and December 2015. One hundred and sixteen publications that dealt with food microbiology were reviewed for general analysis, while 66 papers on contamination of pathogenic bacteria were used for meta-analysis of prevalence. The food items were split into two categories: raw foods and ready-to-eat (RTE) foods (including street food and beverages) for meta-analysis. Majority of the reviewed studies (67.2%, 78/116) dealt with food of animal origin: 38.8% for meat and eggs, 17.2% for dairy products and 11.2% for aquatic products. Only 8.6% examined foods of plant origin (fruits and vegetables). The remaining 24.1% was the composite RTE food and beverages. Enterobacteriaceae, Escherichia coli, Salmonella, Staphylococcus aureus and Listeria monocytogenes were the most frequently reported organisms in those studies. Although the data were highly heterogeneous, a striking feature is high prevalence of the major pathogens in RTE foods, almost as high as in raw foods. E. coli averaged at 37.6% in raw foods and 31.6% in RTE foods. The corresponding prevalence for Salmonella was 19.9% vs 21.7%; S. aureus, 27.8% vs 25.1% and L. monocytogenes, 19.5% vs 6.7%. The average prevalence of foodborne pathogens in these countries was 34.2% (29.0-39.3%). Differences in food types as well as non-uniform protocols for sampling and identification might have contributed to high heterogeneity (I2 >97%) although some high prevalence data could be factual with extensive varieties of raw and RTE foods. Need for improved hygienic practices in handling of raw or RTE foods are suggested. Implementation of surveillance programs that use uniform laboratory protocols across the region could give homogeneous results.