Survival of Lactobacillus rhamnosus GG as Influenced by Storage Conditions and Product Matrixes

Mortality resulting from diarrhea especially that occurs in children younger than 5 y of age ranks 3rd among all deaths caused by infectious diseases worldwide. Probiotics such as Lactobacillus rhamnosus GG are clinically shown to effectively reduce the incidence of diarrhea in children. A food substrate is one of the major factors regulating the colonization of microorganisms in human gastrointestinal tracts. Peanut butter is a nutritious, low-moisture food that could be a carrier for probiotics. In this study, we observed the influence of storage conditions and product matrixes on the survival of L. rhamnosus GG. Cells of L. rhamnosus GG were inoculated into full fat or reduced fat peanut butter at 10(7) CFU/g. Inoculated peanut butter was stored at 4, 25, or 37 degrees C for 48 wk. Samples were drawn periodically to determine the populations of L. rhamnosus GG. Results showed that there was no significant decrease in the viable counts of L. rhamnosus GG in products stored 4 degrees C. The survivability of L. rhamnosus GG decreased with increasing storage temperature and time. Product matrixes did not significantly affect the survival of L. rhamnosus GG except at 37 degrees C. Populations of L. rhamnosus GG were preserved at >6 logs in products stored at 4 degrees C for 48 wk and at 25 degrees C for 23 to 27 wk. At 37 degrees C, the 6-log level could not be maintained for even 6 wk. The results suggest that peanut butter stored at 4 and 25 degrees C could serve as vehicles to deliver probiotics.