Rehydration and equilibration (4 h) of feeds and feed ingredients at water/sample ratios (vol/wt) of 1.4 to 3.2 did not markedly increase recovery of Salmonella spp. in the slurry when analyzed by standard cultural and direct enrichment methods. Of 143 naturally contaminated samples examined, equilibration increased levels of detection from 106 to 109 positive samples by the standard cultural method and from 103 to 112 by direct enrichment. Results suggest that nonhomogeneous distribution of low incident numbers of salmonellae in test samples rather than an equilibration-dependent response provided for the observed heterogeneity in recovery patterns. The novel equilibration approach is of limited application and requires validation on an individual food basis.

Slow rehydration for detection of Salmonella spp. in feeds and feed ingredients.

Recovery of Salmonella Species from Dried Foods Rehydrated by the Soak Method.

Throughout our lifetimes we are subjected to risks and hazards of all kinds. The food supply in the United States is one of the most abundant, nutritious, and safest on earth. However, there is no absolute degree of safety, not even for the food we consume.

Foodborne Agents Causing Illness

Sampling and testing low-moisture foods for detecting foodborne pathogens are a challenge as there are several factors that influence detection that are unique to these types of products These low-a w products are characterized by a water activity <085, and they do not support the growth of foodborne pathogens Case studies have revealed that several outbreaks of salmonellosis have been caused by products contaminated with very few cells Furthermore, results obtained during investigations of several of these outbreaks as well as from laboratory studies revealed that low levels of pathogens such as Salmonella are able to survive for prolonged periods of time in the contaminated foods

Methodological and Sampling Challenges to Testing Spices and Low-Water Activity Food for the Presence of Foodborne Pathogens

Influence of Sample Reconstitution on Recovery of Salmonella Species from Low-Moisture Dairy Foods.

A collaborative study was conducted to compare the relative efficiency of the AOAC rapid rehydration method with the reduced rehydration soak method for the recovery of Salmonella species from nonfat dry milk (NFDM). In the AOAC method, a 25 g sample of NFDM is rapidly rehydrated at a 1:9 sample/water ratio and mixed by swirling. After 60 min, the flask contents are adjusted to a pH of 6.8, and 0.45 mL of 1% aqueous brilliant green dye solution is added. The flasks are then incubated at 35 degrees C. In the soak method, a 25 g sample of NFDM is gently added to the sterile brilliant green (BG) water at a 1:9 sample/BG water ratio and allowed to soak undisturbed for 60 min at room temperature before incubation. Twelve collaborators analyzed 3 shipments of samples with the following results for the AOAC and soak methods: shipment 1-31 and 46 positive samples, respectively, with a 48% increase in detection by the soak method; shipment 3-45 and 66 positive samples, respectively, with a 47% increase in detection by the soak method; shipment 2--no significant difference in recovery of Salmonella species by the 2 methods. It is recommended that the official final action method for the detection of Salmonella species, 46.054-46.067, be revised to use the soak method for the analysis of nonfat dry milk.

Estela La

Papers

Recovery of Salmonella Species from Nonfat Dry Milk Rehydrated Under Rapid and Reduced Pre-enrichment Conditions: Collaborative Study