Lactic acid bacteria in an oat-based non-dairy milk substitute: Fermentation characteristics and exopolysaccharide formation

Nine strains of lactic acid bacteria were tested for fermentation character istics in an oat- based, non-dairy milk substitute, Mill Milk(TM) (MM mediu m). Viable counts, aroma formation, lactic acid production and viscosity we re the parameters investigated. In general, bacterial strains grown at 30 d egreesC yielded a better flavour and higher viable counts than those incuba ted at 37 degreesC. Strains were selected for their capacity to produce exo polysaccharides in a semi-defined medium. Lactobacillus delbrueckii subsp. bulgaricus NCFB 2772 was chosen for further fermentation experiments, using yoghurt as a control. Production of exopolysaccharide and shear thinning p roperties were measured using a viscosimetric method. A combination of temp erature stress and an increased carbon nitrogen ratio was shown to affect t he production of exopolysaccharide. Increased viscosity was found after inc ubation at a low temperature using glucose as a supplementary carbon source . The production of exopolysaccharides was also favoured by prolonged incub ation times. The use of physical factors such as time and temperature in co mbination with chemical factors, i.e. media and carbon nitrogen levels, wer e crucial in the course of improving exopolysaccharide production during fe rmentation in the MM medium.