Methods for the recovery of Salmonella spp. from carboxymethylcellulose gum, gum ghatti, and gelatin.

R M Amaguaña, T S Hammack, W H Andrews

Index: J. AOAC Int. 81(4) , 721-6, (1998)

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Abstract

Foods analyzed for Salmonella spp. by the procedure in the U.S. Food and Drug Administration's Bacteriological Analytical Manual are preenriched at a 1:9 test portion/broth ratio. Various thickening agents preenriched at this ratio become viscous and nonpipettable after 24 h incubation at 35 degrees C. The effects of 3 factors (presence of inorganic salts, adjustment of pH, and presence of enzymes) on the viscosity of the test portion/preenrichment mixtures of various thickening agents during incubation were determined. Reduction of the viscosities of these thickening agents was accomplished as follows: carboxymethylcellulose gum, addition of cellulase to a final concentration of 0.10% in lactose broth preenrichment and incubation with no pH adjustment; gum ghatti, addition of NaCl to a final concentration of 0.10% in lactose broth preerichment and adjustment of the pH to 6.5; and gelatin, addition of papain to a final concentration of 0.10% in lactose broth preenrichment and adjustment of the pH to 6.8. With these modified preenrichments, 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.