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Survivability of Salmonella pathogens in powder goat milk stored under refrigeration and room temperatures for 6 months.

R. Paswan



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Survivability of Salmonella pathogens in powder goat milk stored under refrigeration and room temperatures for 6 months.
R. Paswan*1, A. Mishra2, Y. W. Park1. 1Fort Valley State University Fort Valley, GA, 2University of Georgia Athens, GA.

Powder milk has the advantage of controlling the growth of pathogenic and spoilage microorganisms due to its low water activity (aw), while a dry food often can pose a possible food safety risk due to the survival of pathogens in the product. The objective of this study was to investigate the survivability of Salmonella pathogens in powder goat milk (PGM) under different storage conditions. The study was conducted in a 3 � 2 � 10 factorial experiment, with 3 batches of commercial PGM products stored at 2 temperatures (4�C and 25�C) and 10 storage periods (0, 3, 7, 14, 21, 30, 60, 90, 120 and 180 d). Three serotypes of Salmonella pathogens (Salmonella Agona, Salmonella Enteritidis, and Salmonella Tennessee) were obtained from the University of Georgia, Culture Bank, Athens, GA. A 10 g PGM sample in duplicate was inoculated as following steps: A 5 g PGM sample was placed in a sterile 120 mL amber glass bottle and 0.1 mL fresh culture Salmonella was inoculated to the PGM sample, then additional 5 g sample was added to the inoculated sample, and shaken vigorously to distribute the inoculum homogeneously. All inoculated and non-inoculated samples were stored at 2 temperatures and 10 storage periods, and examined the survivability of the pathogens in the PGM products. Results showed that the initial Salmonella counts were 7.103 log cfu/g at both temperatures. The viable Salmonella counts greatly decreased at the first 3 d by about 0.94 and 1.40 log cfu/g at 4�C and 25�C, respectively, and then the same levels were sustained 14 d. Further reduction occurred about 0.32 log cfu/g at 4�C and about 0.61 log cfu/g decrease at 25�C at 30 d storage. Continuous reductions were observed at 6-mo storage with additional 0.29 and 0.69 log cfu/g, respectively, at 4�C and 25�C treatments. At 180 d, the samples stored at 4�C had 1.15 log cfu/g greater survival of Salmonella pathogen than those stored at 25�C. It was concluded that Salmonella pathogens in the PGM products stored at 4�C for 180 d survived better than those stored at 25�C with the same aw and moisture content.

Keywords: Salmonella, survivability, powder goat milk.

Biography: Roshan Paswan is a graduate student working for MS degree at Fort Valley State University, Fort Valley, GA. His major area of thesis research is food microbiology, mainly in survivability of pathogens especially on Salmonella in dehydrated goat milk products.