Peanut butter with probiotics can inhibit Salmonella and Listeria growth under simulated gastrointestinal conditions

Summary

Peanut butter is being used as a major ingredient of Ready to Use Therapeutic Foods (RUTFs) for the treatment of severe malnutrition. Studies conducted in our laboratory have shown that peanut butter matrix is able to protect different probiotic bacteria during storage and under simulated gastrointestinal conditions. Thus, "probiotic peanut butter" has been proposed as a possible intervention to address malnutrition and diarrhea concurrently in developing countries. This study investigated the behavior of probiotics and selected bacterial pathogens co-inoculated into peanut butter during gastrointestinal simulation. 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 37oC. Sample pH, titratable acidity, and pathogen populations were determined. Agar diffusion assay was performed to assess the inhibitory effect of probiotic culture supernatants towards inoculated pathogens. Antibacterial effect of crude bacteriocin extracted from cultured probiotics was also evaluated. After 24 h of incubation, 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 populations of Salmonella and Listeria. Supernatants of Bifidobacterium and Lactobacillus cultures inhibited the growth of the two inoculated pathogens. Crude bacteriocin extracted from probiotic cultures had a strain-specific inhibitory effect only towards L. monocytogenes. Results of the study suggest that probiotics in "peanut butter" survived simulated gastrointestinal conditions and inhibited the growth of Salmonella/Listeria. Peanut butter is a plausible carrier to deliver probiotics to improve the gastrointestinal health of children in developing countries.

Situation

Approximately 760,000 pre-school children in developing countries die from diarrhea related causes each year. Another devastating medical condition, severe acute malnutrition affects almost 20 million preschool children worldwide and is a causative factor of a third of the deaths that occur in these children. A vicious cycle exists between malnutrition and diarrhea; and diarrhea is both a cause and a consequence of malnutrition in pre-school children. Reports of numerous clinical studies suggest that probiotics are effective in the control and prevention of diarrhea in children. Probiotics can promote gastrointestinal health by inhibiting pathogen growth and preventing pathogen attachment and colonization via antagonism. To receive these benefits, it is important that probiotic bacteria survive in the gastrointestinal tract and colonize the intestinal walls. It has been documented that food matrixes support probiotic survival and colonization, thus, the type of food used for probiotic delivery may influence their actions. Peanut butter is being used as a major ingredient of RUTFs for the treatment of severe malnutrition. The purpose of this research was to study the effect of a commercial probiotic mixture (containing Lactobacillus, Bifidobacteirum and Streptococcus/Lactococcus strains) on Salmonella enterica or Listeria monocytogenes co-inoculated into peanut butter during a simulated gastrointestinal study and the ability of these probiotics in inhibiting the growth of the two pathogens.

Response

Peanut butter homogenates were inoculated with Salmonella/Listeria strains (5 log CFU ml-1) and lyophilized or cultured probiotics (9 log CFU ml-1). Inoculated peanut butter homogenates were exposed to simulated gastrointestinal conditions for 24 h at 37oC. Sample pH, titratable acidity, and pathogen populations were determined during the course of the experiment. Agar diffusion assay was performed to assess the inhibitory effect of probiotic culture supernatants to the inoculated bacterial pathogen. Antibacterial effect of crude bacteriocin extracted from cultured probiotic cultures was also evaluated.

Impact

The presence of probiotics caused a significant reduction (p<0.05) in the population of Salmonella and Listeria. Supernatants of Bifidobacterium and Lactobacillus cultures inhibited the growth of the two inoculated pathogens. Crude bacteriocin extracts had a strain-specific inhibitory effect only towards L. monocytogenes. Results suggest that peanut butter is a plausible carrier to deliver probiotics to improve the gastrointestinal health of children in developing countries.

State Issue

Food Safety

Details

• Year: 2016
• Geographic Scope: International
• County: Spalding
• Program Areas:
  • Agriculture & Natural Resources