Texture promoting capacity and EPS formation by lactic acid bacteria in three different oat-based non-dairy media

Four strains of lactic acid bacteria were used as pure or mixed cultures to investigate the texture-promoting capacity and exopolysaccharides (EPS) formation in three different oat-based, non-dairy milk products, Adavena G40, Adavena M40 (both with a dry matter content of 20%) and Mill Milk (with a dry matter content of 10%). Viscosity was measured at two different shear rates during 2 min of shear thinning. The highest viscosity was measured at a shear rate of 129 s–1 when a mixed culture consisting of Lactobacillus delbrueckii subsp. bulgaricus NCFB 2772 and Lactobacillus brevis DSM 1269 was grown at 30 °C in the medium containing mostly glucose as the carbohydrate source (Adavena G40). The mixed culture consisting of Lactobacillus delbrueckii subsp. bulgaricus NCFB 2772 and Streptococcus thermophilus DSM 20259 gave the highest viscosity when using the medium with a dry matter content of 20% and maltose as the main carbohydrate source (Adavena M40). The EPS formation in the Adavena G40 medium was confirmed by isolating the soluble polymer fraction after fermentation. A higher yield of polymer dry mass was obtained from the samples with higher viscosity. The study shows that the co-operative growth that occurs when using mixed cultures also influences the EPS formation and final viscosity in the different oat-based media. This knowledge is of importance when strains are selected for the development of new kinds of fermented, oat-based, non-dairy products.