AimsThis study observed the behaviour of probiotics and selected bacterial pathogens co-inoculated into peanut butter during gastrointestinal simulation. Methods and ResultsPeanut butter homogenates co-inoculated with Salmonella/Listeria strains (5logCFUml(-1)) and lyophilized or cultured probiotics (9logCFUml(-1)) were exposed to simulated gastrointestinal conditions for 24h at 37 degrees C. Sample pH, titratable acidity and pathogen populations were determined. Agar diffusion assay was performed to assess the inhibitory effect of probiotic culture supernatants with either natural (380 (Lactobacillus), 378 (Bifidobacteirum) and 517 (Streptococcus/Lactococcus)) or neutralized (60) pH. Antibacterial effect of crude bacteriocin extracts were also evaluated against the pathogens. After 24h, samples with probiotics had lower pH and higher titratable acidity than those without probiotics. The presence of probiotics caused a significant reduction (P<005) in pathogen populations. Supernatants of Bifidobacterium and Lactobacillus cultures inhibited pathogen growth; however, the elevation of pH diminished their antibacterial activities. Crude bacteriocin extracts had a strain-specific inhibitory effect only towards Listeria monocytogenes. ConclusionProbiotics in peanut butter' survived simulated gastrointestinal conditions and inhibited the growth of Salmonella/Listeria. Significance and Impact of the StudyPeanut butter is a plausible carrier to deliver probiotics to improve the gastrointestinal health of children in developing countries.