Microbiology of siljo, a traditional Ethiopian fermented legume product

Abstract

Siljo was prepared by thoroughly cooking powdered horsebean (Vicia faba) in safflower (Carthamus tinctorius) extract into a semi-solid slurry and then adding to it untreated black mustard (Brassica nigra) powder after cooling to 50°C. The black mustard powder was the source of starter microorganisms, with Lactobacillus acidophilus, L. plantarum and L. delbruekii initiating and later dominating the fermentation process. The pH of the fermenting mass dropped to 4.5 within 36 h and reached 4.0 at 168 h. Aerobic mesophilic bacteria and lactic acid bacteria were each present at about 1×10(10) c.f.u./ml after 36 h of fermentation but Enterobacteriaceae were never detected. The dominant aerobic mesophilic flora consisted of Micrococcus, Bacillus and Lactobacillus spp. Crude protein, crude fat and ash increased slightly during the fermentation, with final values of around 28%, 25% and 7%, respectively, but there was a marked increase in protein availability and concentration during the fermentation.