RESUMO
The presence of large amounts of probiotic bacteria in a sample may interfere with the detection of undesirable microorganisms. To illustrate this, infant formula with various strains of probiotic bacteria and the corresponding probiotic culture powders and premixes were artificially contaminated with low levels of Salmonella. Recovery of Salmonella was generally very poor when the conventional pre-enrichment procedure using buffered peptone water (BPW) was applied. However, this problem was overcome by adding antimicrobial compounds to selectively suppress the growth and/or metabolic activity of the probiotic bacteria and increasing the buffering capacity of the pre-enrichment broth. It is recommended that these analytical constraints are already addressed during the development phase of new probiotic products.
