Microbiological studies of Kirario, an indigenous Kenyan fermented porridge based on green maize and millet

Abstract

The objective of this study was to isolate, characterize and identify the lactic acid bacteria involved in the fermentation of Kirario, a traditional fermented porridge based on green maize, millet and/or sorghum. The traditional production of Kirario involves spontaneous fermentation of green maize and millet/sorghum in fermentation vessel (earth ware pots, plastic jars and buckets) at ambient temperature for 1-2 days. The traditional art of Kirario preparation was studied and documented with the aid of questionnaires. The biochemical and microbial profile changes during fermentation of Kirario were monitored for 48 hours. The information obtained was used to characterize and identify the microflora involved in Kirario fermentation. The average total viable counts (TVC), lactic acid bacteria (LAB), lactococci, and yeasts and moulds of samples from various localities in the study region (Meru North District) were 9.30, 9.63, 8.62, and 4.83 10gIOcfu/rnl respectively. The coliform counts in two of the samples was <l log cfu/ml while in other samples no coliforms were detected. This is an indication of either good hygienic processing or effect of inhibition of growth of coliforms during fermentation. The development of pH, titratable acidity and microbial counts were monitored at 6 hourly intervals for 2 days (48 hours). The initial pH of 6.4 dropped to 3.3 at the end of the fermentation, while the titratable acidity increased to 3.159'(1 from an initial value of 1.049'(1.The TVC, LAB, lactococci. yeasts and molds increased from counts of 8.20, 8.18. 7.20 and 5.86 to 9.64, 9.55, 5.38 and 0.70 loglo cfu/ml respectively at the end of the 48- hour fermentation. Thirty LAB strains were isolated from samples of Kirario and identified using API 50 CHL identification systems. The study showed that the Lactobacillus, Leuconostoc and Lactococcus genera were the dominant lactic acid bacteria in Kirario. The isolated LAB were identified as Leuconostoc mesenteroides ssp. mesenteroides/detranicum J & 2, Leuconostoc citreum, Lactococcus lactis ssp. Lactis J & 2, Lactococcus raffinolactis, Lactobacillus planta rum, Lactobacillus brevis, Lactobacillus coli inoides and Lactobacillus coprophilus. Lactobacillus plantarum 1, was the most predominant LAB [about 47% of total LAB isolates], followed by Leuconostoc mesenteroides ssp. mesenteroides/detranicum J which , accounted for 16% of the LAB isolates.