title: Developing a two-step heat treatment for inactivating desiccation-adapted Salmonella spp. in aged chicken litter.
abstract: The effectiveness of a two-step heat treatment for eliminating desiccation-adapted Salmonella spp. in aged chicken litter was evaluated. The aged chicken litter with 20, 30, 40, and 50% moisture contents was inoculated with a mixture of four Salmonella serotypes for a 24-h adaptation. Afterwards, the inoculated chicken litter was added into the chicken litter with the adjusted moisture content for a 1-h moist-heat treatment at 65 °C and 100% relative humidity inside a water bath, followed by a dry-heat treatment in a convection oven at 85 °C for 1 h to the desired moisture level (<10-12%). After moist-heat treatment, the populations of Salmonella in aged chicken litter at 20 and 30% moisture contents declined from ≈6.70 log colony-forming units (CFU)/g to 3.31 and 3.00 log CFU/g, respectively. After subsequent 1-h dry-heat treatment, the populations further decreased to 2.97 and 2.57 log CFU/g, respectively. Salmonella cells in chicken litter with 40% and 50% moisture contents were only detectable by enrichment after 40 and 20 min of moist-heat treatment, respectively. Moisture contents in all samples were reduced to <10% after a 1-h dry-heat process. Our results demonstrated that the two-step heat treatment was effective in reducing >5.5 logs of desiccation-adapted Salmonella in aged chicken litter with moisture content at or above 40%. Clearly, the findings from this study may provide the chicken litter processing industry with an effective heat treatment method for producing Salmonella-free chicken litter.
authors.affiliation: 1 Department of Biological Sciences, Clemson University , Clemson, South Carolina.
authors.forename: Zhao
authors.initials: Z
authors.lastname: Chen
authors.forename: Hongye
authors.initials: H
authors.lastname: Wang
authors.forename: Xiuping
authors.initials: X
authors.lastname: Jiang
mesh_terms: D000222:Adaptation, Physiological; D000641:Ammonia / Q000032:analysis; D000822:Animal Husbandry / Q000191:economics / Q000379:methods*; D000818:Animals; D058491:Bacterial Load; D002140:California; D002645:Chickens; D004203:Disinfection / Q000379:methods*; D006358:Hot Temperature; D007220:Industrial Waste / Q000032:analysis* / Q000191:economics; D050296:Microbial Viability; D058871:Organic Agriculture / Q000191:economics; D012475:Salmonella / Q000254:growth & development* / Q000502:physiology; D012987:Soil / Q000737:chemistry*; D012988:Soil Microbiology; D014867:Water / Q000032:analysis
chemical_list: D007220:Industrial Waste; D012987:Soil; D014867:Water; D000641:Ammonia