The effect of surface activity of pyrodextrins on their assimilability by selected strains of bacteria from genus Lactobacillus

Four commercial products based on pyrodextrins and differing in viscosity and digestibility in vitro were studied in the aspect of their surface activity. Their assimilability by probiotic strains of bacteria from genus Lactobacillus was checked by analysis of the growth of four bacteria strains cultured on a modified MRS medium containing the commercial pyrodextrins instead of glucose. Interfacial tension at the air/water and toluene/water interfaces was measured with a du Noüy tensiometer. Experimental isotherms were approximated with the Szyszkowski equation and surface parameters were calculated. It was established that commercial pyrodextrins show digestibility reduced to about 50% as well as surface activity that makes them useful as emulsifiers. The presence of dextrins in the medium has no effect on the growth of any of the probiotic Lactobacillus bacteria strains studied, but significantly modifies their metabolic activity resulting in changes in type and amount of the short chain fatty acids produced.