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Microbial dynamics during the fermentation of Wakalim, a traditional Ethiopian fermented sausage

Bacha, Ketema, Jonsson, Hans, Ashenafi, Mogessie
Journal of food quality 2010 v.33 no.3 pp. 370-390
Enterobacteriaceae, Gram-negative bacteria, Lactobacillus, Pediococcus, Staphylococcus, beef, carbohydrates, commercialization, equipment, flavor, flora, lactic acid bacteria, lactic fermentation, multiple strain starters, pH, polymerase chain reaction, repetitive sequences, ribosomal DNA, sausages, shelf life, titratable acidity, traditional foods, water content
Wakalim is a spiced traditional Ethiopian fermented beef sausage. Early stages (0-12 h) of wakalim fermentation were dominated by lactic acid bacteria and aerobic mesophilic bacteria including staphylococci and members of Enterobacteriaceae. Gram-negative bacteria were below detectable level after day 4 of fermentation. Staphylococci were detected at low levels (around 4 log cfu/g) until the end of fermentation. Lactic acid bacteria grew and dominated the flora at the end of fermentation. Various species of Lactobacillus and Pediococcus initiated the fermentation and the lactic flora was finally dominated by Lb. plantarum1 and Ped. pentosaceus1. The pH of the fermenting wakalim dropped from 5.5 ± 0.22 to 4.1 ± 0.19 while the titratable acidity increased from 0.09 to 0.6% in the course of fermentation. Moreover, moisture content of the fermenting wakalim dropped from 66.5% ± 2.12 to 22.0% ± 0.71 during the 6 days of fermentation. Molecular characterization, using 16S rDNA partial sequence analysis and repetitive sequence-based polymerase chain reaction, of the isolates confirmed some of the earlier phenotypic identification made based on API carbohydrate fermentation profile. Some of the strains were, however, identified as different species of the same genus or entirely different genus. The findings of this study are the first of their kind from traditional Ethiopian fermented sausage and could have paramount importance as a baseline data for large-scale production of the traditional product using defined starter cultures. Moreover, the strains characterized in this study could be exploited as potential starter cultures for the commercialization of wakalim. Traditional fermented foods and beverages are products of spontaneous fermentation. This type of process results in microbiological and chemical variability in the products, as it depends on the microflora naturally present in the substrates, on utensils and equipment used. Isolation and characterization of the microorganisms involved in the fermentation, and identification of the most important starter species may help to undertake controlled fermentation with selected mixed culture starters to optimize the process conditions. This would result in products which are consistent and definable in their flavor and other biochemical parameters, have good keeping quality and are, in general, wholesome. This may pave the way for large-scale commercial production, which may also improve the shelf life of the products, and reduce wastage during processing, which is significant at household level. The strains characterized in this study could be exploited as potential starter cultures for the commercialization of wakalim.