Probiotic potential of spontaneously fermented cereal based foods – A review

The realization that food has a role beyond provision of energy and body forming substances has shifted scientific investigations with growing interest in the research and development of functional foods. A lot of attention is being focused on probiotics due to the enormous support showing health benefits. Probiotics are associated with fermented foods and it is therefore of importance that spontaneously fermented foods, that are so common in Africa, be assessed for their probiotic attributes. These foods are within the economic means of the people and are widely accepted in populations where they are produced. The foods have relatively long shelf-lives under ambient temperatures (without spoiling), are widely accepted especially by the vulnerable groups such as children, expectant/breastfeeding mothers, the aged and are commonly served to the sick and recovering persons. These foods would therefore render an invaluable health benefit to communities when consumed and would impart an invaluable economic benefit to society. Probiotics are associatedwith lactic acid bacteria that are commonly found in fermented foods. This paper reviews studies that have been carried out to enumerate, isolate, characterize and identify the microorganisms involved in the spontaneous fermentations of cereal based products and their assessments for  potential probiotic attributes

Microbiological quality and safety of raw and pasteurized milk marketed in and around Nairobi Region

The microbiological quality of raw and pasteurized milk marketed in Nairobi and its environs was determined. Milk samples were collected randomly at milk selling points from three market areas: rural (Kiambu/Ngong), urban (East/West of Tom Mboya street) and slum (Kibera/Mathare). Samples were analysed for titratable acidity, total viable count (TVC), Staphylococcus aureus, coliforms and Enterobacteriaceae. Titratable acidity was determined using titration method, while TVC, S. aureus and Enterobacteriaceae were determined by the spread plate methods and coliforms were determined by most probable number. Data collected were subjected to analysis of variance using Genstat statistical package. The mean acidity was 0.20% lactic acid (LA), while mean counts for TVC, S. aureus, coliforms and Enterobacteriaceae were 6.05, 3.46, 2.30, and 3.93 log10cfu/ml, respectively. The  ercentage of milk samples with acidity values greater than 0.18% LA, the upper limit set by Kenya Bureau of Standards (KEBS), was 52.8 %. Total viable count (TVC) greater than 106 cfu/ml, was detected in 95.2% and 21.4% of raw and pasteurized milk, respectively. Coliform counts greater than 4.70 and 1.0 log10cfu/ml for raw and pasteurized milk were detected in 77.8% and 4.8%, respectively of raw and pasteurized milk samples collected. Enterobacteriaceae and S. aureus were detected with mean counts ranging from 6.08-6.86 and 5.82-6.32 log10/ml, respectively. Highest mean acidity and counts were recorded from slum areas of Nairobi and there were significant differences between raw and pasteurized milk (P<0.05). The poor bacterial quality coupled with high acidity of raw milk, indicates poor hygienic practices and lack of temperature control during marketing. The incidence of high acidity and bacterial counts in pasteurized milk could indicate post process contamination and/or inappropriate storage of the milk. Most vendors of pasteurized milk were observed selling directly from the distributor crates without refrigerated storage. The rapid deterioration of raw and pasteurized milk marketed in Nairobi, at the time of this study, may be largely due to poor hygienic standards and non-adherence to temperature controls during handling, distribution and marketing. This requires urgent attention by the appropriate authorities, because the poor microbiological quality of raw milk and pasteurized milk may expose consumers to health risks associated with the consumption of contaminated milk.Key words: Marketed milk, quality, acidity, total viable count, coliforms, enterobacteriaceae, Staphylococcus aureu

Partial characterisation and identification of lactic acid bacteria involved in production of ikii: a traditional fermented maize porridge by the Kamba in Kenya

Ikii is a fermented maize grits porridge prepared by the Kamba community in Kenya and is a favourite amongst children, breastfeeding mothers and the aged. It is a food commonly served to the sick and recovering persons and can store for as long as a week under ambient temperatures (25 – 30 oC) without spoiling. The pH during the fermentation process of ikii showed a decreasing trend from an initial average value of 6.4 to an average value of 3.9 at 36 hours and through to 72 hours, indicating production of acid. The population and diversity of lactic acid bacteria involved in production of ikii was studied. Lactic acid bacteria (LAB) were found to be the dominant microorganisms that bring about fermentation process leading to production of ikii. After 36 hours of the fermentation period, LABs and yeasts were found to exhibit a synergistic relationship that boosted the population growth of each other. From 40 samples of ikii suspension, 185 lactic acid bacteria strains were isolated, characterised and identified by use of morphological features, biochemical and phenotypical tests as well as sugar fermentation profiles of the API 50 CHL kit. The genus Lactobacillus (62%) formed the dominant microbiota and the rest of the isolated strains belonged to the genus Pediococcus (38%). Of the isolated strains, L. fermentum formed the dominant species (43%); other species were L. plantarum (10%), L. confusus (8%) and L. rhamnosus (1%). Keywords: Traditional fermented maize porridge; Lactic acid bacteria; Ikii; Kamba. Journal of Tropical Microbiology and Biochemistry Vol. 4 (1) 2008: pp. 3-1