VIABILITY OF MICROFLORA OF MARKET FERMENTED MILK PRODUCTS IN SIMULATED CONDITIONS OF GASTRIC AND DUODENUM

Background. The non-probiotic lactic acid bacteria have only rarely been used in in vitro or in vivo studies, because they are not considered to exert health benefits. To exert the beneficial effect in human organism, LAB needs to meet some criteria, for example the viability in the gastrointestinal tract (GIT). The aim of this work was to determine the viability of microflora of chosen market non-probiotic fermented milk products in simulated gastric and duodenal fluids. Material and methods. Ten market non-probiotic fermented milk products bought in Warsaw were used in this study. Ten grams of each product have been suspended in simulated gastric fluid, and then the mixture has been transferred into simulated duodenal fluid. Immediately after bacteria inoculums addition and at the end of the experiment, the number of lactobacilli and lactococci was measured. Results. The number of lactococci or streptococci decreased by 0.1-0.3 log cycle after 3 h in gastric mixture. Only in one yoghurt the population of streptococci decreased by 0.9 log cycle. The population of lactobacilli did not change in condition of simulated gastric fluid. The significant reduction of lactobacilli, lactococci and streptococci population was observed after the transfer of mixture into simulated duodenal fluid and incubation in this condition for 5 h. After the end of experiments in every studied sample the number of microflora remained at the level above 6 log CFU/mL. Conclusions. The results indicate that the condition simulating gastric fluid is not a menace to viability of lactic acid bacteria, if they are protected by milk products. The significant reduction of bacteria number in simulated duodenal fluid was probably caused by cell shock to intensive pH change of environment and loss of protective barrier caused by digestive enzymes activity.