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Recovery of Salmonella enterica Serovars Typhimurium and Tennessee in Peanut Butter after Electron Beam Exposure
Author(s) -
Matak Kristen E.,
Hvizdzak Andrea L.,
Beamer Sarah,
Jaczynski Jacek
Publication year - 2010
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/j.1750-3841.2010.01729.x
Subject(s) - salmonella , salmonella enterica , serotype , food science , inoculation , food irradiation , peanut butter , chemistry , biology , irradiation , microbiology and biotechnology , bacteria , horticulture , genetics , physics , nuclear physics
Abstract: The effect of electron beam (e‐beam) radiation on the recovery of Salmonella serotypes Tennessee (ATCC 10722) and Typhimurium (ATCC 14028) in creamy peanut butter over a 14‐d storage period at 22 °C was studied. Each Salmonella type was independently inoculated into peanut butter and subjected to e‐beam doses that ranged from 0 to 3.1 kGy, confirmed by film dosimetry. After 2‐, 4‐, 6‐, 8‐, and 14‐d of storage, microbial analyses were conducted. Survivors were recovered on growth and selective media using standard spread‐plating methods. Microbial counts (CFU/g) were log‐converted and differences were determined by ANOVA and Tukey's Honestly Significant Differences test. When samples were not e‐beam‐treated, there were no significant changes ( P > 0.05) in microbial numbers over time. In e‐beamed samples, microbial numbers decreased over time; however, reductions were not always significant. Initial recovery rates (R‐rates) 2 d after e‐beam treatment were significantly different for the 2 strains of Salmonella and between recovery media ( P < 0.05); however, these differences did not persist for the remainder of the storage period ( P > 0.05) indicating that injured cells were not able to survive in the high‐fat, low‐water activity peanut butter environment. R‐rates for both strains of Salmonella were maintained until day 14 when there were significant reductions in Salmonella Typhimurium ( P < 0.05). These results indicate that Salmonella Tennessee and Salmonella Typhimurium will survive in peanut butter when exposed to nonlethal doses of e‐beam irradiation. Practical Application : Electron beam (e‐beam) irradiation is an alternative to thermal processing; this technique inactivates microorganisms and insects that might be present in a food by generating radiation by accelerated electrons that inactivate organisms directly because of interaction with cell components and indirectly by producing free radicals that disrupt integrity of the cell membrane. E‐beam radiation will reduce the number of probable microbiological hazards that could be present while the food remains generally unaffected in texture, taste, and nutritional value. A recent study showed e‐beam irradiation to be effective at reducing both Salmonella Tennessee and Typhimurium in peanut butter by one log after exposure to less than 1 kGy, highlighting the need to explore this process further.