Use of Bacillus subtilis S499 to control mould growth during malting of red sorghum from the D.R. of Congo

In this work, moulds growth was monitored during malting of a red sorghum from D.R. of Congo. Results obtained with chemical treatments [diluted alkalines: NaOH 0.2% (T1) and Ca(OH)2 0.1% (T2)] were compared with those of biocontrols [use of Bacillus subtilis S499 108 cells / mL: supernatant + cells (T3), cells (T4) and cells-free supernatant (T5)]. Chemical treatments have shown the highest fungal contamination levels, the highest malting loss, but better enzyme activities (α and β-amylases, limit-dextrinase, α-glucosidase and β-glucanase). The inhibition tests showed that the concentration of lipopeptides is correlated with the reduction of moulds growth. Malting trials with starters of Bacillus subtilis S499 showed that culture dilution affects the growth of moulds during red sorghum malting. The combination of a chemical treatment such as diluted NaOH with a biocontrol could be used to improve sorghum malts quality in terms of different enzymes activities and by reducing the level of fungal contamination.
Key words: Bacillus subtilis S499, mould, sorghum malting