Abstract

Spontaneously-fermented RBS contains a variety of LAB and bacterial metabolites with potential applications as sources of functional ingredients. In this work, the EPS production capacities of the dominant LAB separated from spontaneously fermented RBS was investigated. Lactobacillus acidophilus was identified as the dominant isolate via biochemical and molecular investigations. The total carbohydrate, protein and phosphorus contents of the 2.04 x 10(6) Da EPS were 254.9 g/L, 0.095 g/L, and 0.36 w/w, respectively. HPLC was used for compositional assessment in terms of monosaccharide constituents, revealing that glucose, galactose and maltose were the major components of the EPS produced by L. acidophilus. The EPS was identified using FT-IR, H-1 and C-13 NMR spectra. FT-IR analysis demonstrated the polysaccharide nature of the EPS; the presence of alcoholic, aromatic and carboxylic acid groups was confirmed via their respective stretching vibrations. The microbial EPS extracted from L. acidophilus was identified as a linear alpha(1 -> 6) polysaccharide. Also, the percentage inhibition of DPPH by the EPS was significant (P < 0.05). Thus, potential antioxidant characteristics were demonstrated as important aspects of the EPS produced by the strain isolated from fermented RBS.