Effect of Fermentation on Nutrient and Anti-Nutrient Contents of Ground-Cooked Lima Bean (Phaseolus lunatus) Seeds using Bacillus subtilis and Bacillus pumilus

Aim: This study investigated the effect of single cultures of Bacillus subtilis and B. pumilus on nutrient and anti-nutrient contents of ground-cooked Lima bean seeds.

Methodology: Lima bean seeds were ground and fermented naturally as well as with single starters of B. subtilis and B. pumilus (previously isolated from naturally fermented Lima bean seeds) for nine days. Microbial analyses, pH, total titratable acidity and the temperature of the fermenting samples were carried out on daily basis, nutritional composition at two day intervals while the anti-nutrient contents were determined before and after the fermentation period.

Results: Higher microbial counts were observed in starter fermented samples than the naturally fermented samples. The pH increased throughout the fermentation period with the highest in B. subtilis fermented sample but was not significantly higher (P<.05) than B. pumilus fermented sample while the total titratable acidity which however decreased mostly in B. subtilis was also not significantly different from B. pumilus fermented sample. Temperature increased up to the fifth day in both starter samples but higher in B. subtilis fermented substrate but up to seventh day in naturally fermented sample. Starter culture fermented samples had the highest moisture, fat and ash contents at the end of the fermentation while the protein values increased in all the samples with the highest in B. subtilis fermented sample (25.34%) while B. pumilus and naturally fermented sample contained 24.32% and 22.22% respectively. Oxalate, phytic acid and cyanide were more reduced in naturally fermented sample than the starter fermented samples while the highest reductions were observed in saponin and tannin contents of B. subtilis fermented sample. Organoleptic parameters were rated better in the Lima bean seeds fermented with starter cultures than the naturally fermented sample.

Conclusion: This study revealed that Lima bean seeds fermented with single starter cultures of B. subtilis and B. pumilus enhanced the nutrient contents and organoleptic qualities of the products.