INFLUENCE OF BRINE COMPOSITION AND CONCENTRATION ON MICROBIAL GROWTH DURING WHOLE COMMON BEAN (Phaseolus vulgaris L) FERMENTATION USING Lb.plantarum BFE 5092

Abstract

Fermentation technology improves the flavour and shelf life of foods while lowering antinutrient levels. Common bean, though a highly nutritious food, contains high levels of anti-nutrients. Fermentation can be exploited to lower antinutrients in common bean. Though significant strides have been made in bean milk and flour fermentation, common bean is majorly consumed as whole grain. This study, therefore, was aimed at developing a fermentation protocol for whole common bean. Lactobacillus plantarum BFE 5092 was used as starter culture for fermentation. Salt and salt-sugar at 1%, 2% and 3% solute concentrations were used as brine. The effect of starter culture, solute composition and concentration on the growth of lactic acid bacteria (LAB) was monitored. pH and microbial safety were also monitored during the fermentation process. Inoculation with Lb. plantarum BFE 5092 caused a significant increase (P<0.05) of LAB counts in salt brines compared to spontaneous fermentation but no significant difference (P>0.05) in salt-sugar brines. The pH of salt sugar brine solutions was significantly (P<0.05) lowered during the fermentation process from 6.07 to ≤ 3.75. This inhibited enterobacteria growth while promoting the growth of yeast. In salt brines, the pH was ≥ 4.8 favoring enterobacterial growth while inhibiting yeast growth. Solute concentration had no significant effect (P>0.05) on the growth of LAB, pH and microbial safety during fermentation. The study established that use of salt-sugar brine was effective in promoting the growth of LAB during common bean fermentation. It also lowered the pH to ≤ 3.75 and inhibited enterobacterial growth unlike salt brines.