Lactobacillus plantarum strains: NGL5 and NGL7 previously identified from akamu-a lactic acid bacteria fermented maize food using PCR sequencing analysis were evaluated for inhibitory activity against Eschericia coli NCTC 11560 in fermenting ground maize slurries at 22 and 30°C, and in porridges prepared from 24 h fermented slurries. The L. plantarum strains fermented ground maize slurries and produced significant levels of titratable acidity ≥5 g L^-1 and low pH ≤3.63, displaying inhibitory activity against E. coli NCTC 11560. Inhibition was significantly (p≤0.05) greater at 30°C than at 22°C. At 30°C, E. coli was inhibited after 24 h in the co-inoculation assay (µ < -0.17 h^-1; D value <10 h) and after 180 min in the already fermented slurries (µ < -0.13 min^-1; D value <14 min). In the porridges, E. coli decreased below detection limit after 20 mins. This study showed that E. coli NCTC 11560 introduced during or after fermentation and into freshly prepared porridges from the L. plantarum strains fermented slurries would be unable to survive and proliferate at pH <4.2 and acidity >5 g L^-1. For safety of the product however fermentation has to be for at least 24 h at 30°C or more at 22°C.

Lactobacillus plantarum, maize slurry, fermentation, acidity, inhibition, Escherichia coli