MODIFICATION OF OLIGOSACCHARIDE AND SHORT CHAIN FATTY ACID CONTENT OF COWPEA MILK THROUGH FERMENTATION WITH SELECTED MIXED STARTER CULTURES

Abstract

Cowpea milk was fermented with three mixed starter cultures containing (i) Lactobacillus acidophilus, Bifidobacterium sp, and Streptococcus thermophilus (ABT) (ii) Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus (DT) or (iii) Lactobacillus rhamnosus GR-1 and Streptococcus thermophilus (GT). Effects of these cultures on flatulencecausing raffinose family oligosaccharides and the production of postbiotic short chain fatty acids were determined. The oligosaccharides and short chain fatty acids were determined by high performance liquid chromatography and gas chromatography, respectively. The stachyose content of raw cowpea (1.388±0.23 g/100 g) was higher than raffinose (0.221±0.06 g/100 g), while verbascose was not detected. Cowpea milk fermentation caused 67-100% reduction in raffinose and 20-70% reduction in stachyose in a culture-dependent manner. All the cultures produced propionic acid, butyric acid and valeric acid in differing concentrations but only GT and ABT produced isovaleric acid. The product fermented with DT attained 2430 ppm of propionic acid, which was four times and ten times higher than the concentrations produced by the ABT and GT cultures, respectively. In conclusion, fermentation of cowpea milk with the three starter cultures reduced flatulence-causing oligosaccharides and produced postbiotic short chain fatty acids that might promote health regardless of the survival of the microorganisms in the gut.