An evaluation of the effect of Bacillus cells and Bacillus spores in association with cowpea granules as starter cultures for the fermentation of African oil bean (Pentaclethra macrophylla Bentham) to 'ugba'.

Abstract

Studies on the improvement of the traditional production of 'ugba', a protein-rich fermented African oil bean seed product, were undertaken, by developing starter cultures of Bacillus subtilis cells and spores in association with cowpea granules. The viability of the cells in association remained stable at 94.5% for 6 months at 30 degrees C and for up to 10 months at 4 degrees C while the viability of the spores in association remained stable at ca. 96% for up to 10 months at both 4 and 30 degrees C. The starter cultures resulted in high increases in protease activity from ca 2.8 mg N/min to about 51.6 +/- 0.4 mg N/min in 48 h and a corresponding increase in amino-nitrogen content of ca 2.0 +/- 0.2 mg N 100 g dry matter (DM) to ca 18.5 +/- 0.3 mg N/100 g (DM) during the same period. Changes in the protease activity of the natural process were gradual and increased from 3.0 mg N/min to 38.0 +/- 0.8 mg N/min after 5 days of fermentation. The maximum amino nitrogen content of 'ugba' produced by the starter cultures (18.5 +/- 0.3 mg N/100 g DM) after 2 days was significantly (p <0.05) higher than the maximum amino nitrogen content (12.5 +/- 0.8 mg N/100 g DM), of 'ugba' obtained by the natural process. 'Ugba' produced by the starter cultures were well accepted and compared favorably with the natural product.