Technological properties of Lactobacillus fermentum involved in the processing of dolo and pito, West African sorghum beers, for the selection of starter cultures

AIM: Technological properties of Lactobacillus fermentum isolates involved in spontaneous fermentation of dolo and pito wort were examined to select starter cultures. METHODS AND RESULTS: 264 isolates were screened for antimicrobial activity, acidifying activity, exopolysaccharides (EPSs) and amylase production. An antimicrobial activity was detected for 33.3%, 31.8%, 22.7% and 15.9% of the isolates towards Staphylococcus aureus enterotoxin A producer, Staphylococcus aureus enterotoxin A and B producer, Escherichia coli and Listeria innocua, respectively. A similarity was found between the isolates which were clustered in four groups according to their rates of acidification of sorghum malt broth. The faster acidifying group of isolates (43.48%) had a rate of acidification evaluated as Delta pH of 1.14 +/- 0.15 pH unit after 6 h of fermentation, followed by a second group of isolates (38.08%) with a similar rate of acidification after 9 h of fermentation. From the isolates endowed with an antimicrobial activity, 5.76% belonged to the faster acidifying group and 40.38% belonged to the second group. 88.7% of the isolates had the ability for producing EPSs but not amylase. CONCLUSION: Lactobacillus fermentum ferments dolo and pito wort by lowering the pH and providing organic acids, EPSs and antimicrobial compounds. SIGNIFICANCE AND IMPACT OF THE STUDY: Strains with a rapid rate of acidification, an antimicrobial activity and producing EPSs are suggested to have potential for starter cultures.