METHODS FOR THE RECOVERY OF SALMONELLA SPP. FROM CARBOXYMETHYLCELLULOSE GUM, GUM GHATTI, AND GELATIN

Foods analyzed for Salmonella spp, by the procedure in the U.S. Food a nd Drug Administration's Bacteriological Analytical Manual are preenri ched at a 1:9 test portion/broth ratio. Various thickening agents pree nriched at this ratio become Viscous and nonpipettable after 24 h incu bation at 35 degrees C. The effects of 3 factors (presence of inorgani c salts, adjustment of pH, and presence of enzymes) on the viscosity o f the test portion/preenrichment mixtures of various thickening agents during incubation were determined. Reduction of the viscosities of th ese thickening agents was accomplished as follows: carboxymethylcellul ose gum, addition of cellulase to a final concentration of 0.10% in la ctose broth preenrichment and incubation with no pH adjustment; gum gh atti, addition of NaCl to a final concentration of 0.10% in lactose br oth preerichment and adjustment of the pH to 6.5; and gelatin, additio n of papain to a final concentration of 0.10% in lactose broth preenri chment and adjustment of the pH to 6.8, With these modified preenrichm ents, one Salmonella spp. cell/25 g (representing an approximate most probable number value of 0.04 cell/g) was generally recovered from the thickening agents.