Impact of pre-enrichment broth on recovery of S. typhimurium and reformed water activity on dominance and endurance of Salmonella in Indian sweetmeat milk (doodh) peda

Abstract

Food-borne outbreaks associated with low water activity (aw) foods involve Salmonella contamination, and its control is a significant challenge. In India, milk (doodh) peda is a low aw traditional and popular food. Accordingly, it is essential to determine the prevalence and survival of Salmonella spp. in artificially spiked milk peda stored for an extended period at different aw. Salmonella spp. was not detected in any of the 25 indigenous peda samples. Salmonella did not grow in low aw. However, S. typhimurium ATCC 25241, which was inoculated artificially at a level of 1.5x104 CFU/g, survived in the spiked peda sample at 0.75, 0.56, and 0.32 aw. Survival of S. typhimurium ATCC 25241 was observed for a more extended period (19 days) at lower aw than higher aw. These results confirmed that even though Salmonella spp. was not detected in milk peda samples, but can survive for a long time in contaminated samples. Salmonella survived for a long time by the osmoadaptation mechanism. These results revealed that the survival of S. typhimurium is influenced by aw, and the prevalence of Salmonella in the peda sample was inversely proportional to aw.