title: Influence of probiotics, included in peanut butter, on the fate of selected Salmonella and Listeria strains under simulated gastrointestinal conditions.
abstract: OBJECTIVE
  This study observed the behaviour of probiotics and selected bacterial pathogens co-inoculated into peanut butter during gastrointestinal simulation.
  
  
  RESULTS
  Peanut butter homogenates co-inoculated with Salmonella/Listeria strains (5 log CFU ml(-1) ) and lyophilized or cultured probiotics (9 log CFU ml(-1) ) were exposed to simulated gastrointestinal conditions for 24 h at 37°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 (3·80 (Lactobacillus), 3·78 (Bifidobacteirum) and 5·17 (Streptococcus/Lactococcus)) or neutralized (6·0) pH. Antibacterial effect of crude bacteriocin extracts were also evaluated against the pathogens. After 24 h, samples with probiotics had lower pH and higher titratable acidity than those without probiotics. The presence of probiotics caused a significant reduction (P < 0·05) 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.
  
  
  CONCLUSIONS
  Probiotics in 'peanut butter' survived simulated gastrointestinal conditions and inhibited the growth of Salmonella/Listeria.
  
  
  CONCLUSIONS
  Peanut butter is a plausible carrier to deliver probiotics to improve the gastrointestinal health of children in developing countries.
authors.affiliation: Department of Food Science and Technology, The University of Georgia, Griffin, GA, USA.
authors.forename: Y A K
authors.initials: YA
authors.lastname: Klu
authors.affiliation: Department of Food Science and Technology, The University of Georgia, Griffin, GA, USA.
authors.forename: J
authors.initials: J
authors.lastname: Chen
mesh_terms: D010367:Arachis; D001430:Bacteriocins / Q000494:pharmacology; D001644:Bifidobacterium / Q000502:physiology*; D004337:Drug Carriers; D041981:Gastrointestinal Tract / Q000382:microbiology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007778:Lactobacillus / Q000502:physiology*; D008087:Listeria / Q000187:drug effects* / Q000254:growth & development; D019936:Probiotics / Q000494:pharmacology*; D012475:Salmonella / Q000187:drug effects* / Q000254:growth & development
chemical_list: D001430:Bacteriocins; D004337:Drug Carriers
keywords: Listeria; Salmonella; gastrointestinal fluid; peanut butter; probiotics