Screening of lactic acid bacteria potentially useful for sorghum fermentation

A screening of commercial lactic acid bacteria potentially useful in the improvement of sorghum nutritional quality was done. The aim of this study was to test starter cultures to meet the prerequisites for the establishment of small-scale industrial production of sorghum fermented foods in Africa. Sorghum was fermented with commercial strains of Lactobacillus plantarum, Lactobacillus brevis, Lactobacillus paracasei, Lactobacillus fermentum, Pediococcus pentosaceus and Streptococcus thermophilus. As a result of sorghum prolamins hydrolysis, an increase in the in vitro protein digestibility (IVPD) was promoted. After pepsin digestion, changes occurred in the electrophoretic profile of prolamins, with a decrease of almost all fermented sample spots in comparison with the unfermented sample. Samples in which the decrease of 45 kDa and 66 kDa oligomers was more pronounced, presented higher IVPD. Fourier Transform Infrared spectroscopy in tandem with multivariate analysis showed starch structural changes in samples fermented with Lactobacillus brevis, Lactobacillus fermentum, Streptococcus thermophilus and Pediococcus pentosaceus. This work demonstrates that all tested bacteria promoted beneficial effects on sorghum nutritional quality and are suitable to be used as commercial starters for industrial applications. Streptococcus thermophilus, Lactobacillus brevis and Lactobacillus fermentum are the most promising starters as they lead to higher IVPD values (46.48, 39.19 and 36.73%, respectively). (C) 2010 Elsevier Ltd. All rights reserved.