title: Survival of Salmonella, Escherichia coli O157:H7, and Listeria monocytogenes on raw peanut and pecan kernels stored at -24, 4, and 22°C.
abstract: Cocktails of lawn-collected cells were used to determine the survival of Salmonella, Escherichia coli O157:H7, and Listeria monocytogenes on the surface of raw peanut and pecan kernels. Kernels were inoculated with mixtures of four to five strains at 3 or 6 log CFU/g, dried at room temperature, and then stored at -24 ± 1, 4 ± 2, and 22 ± 1°C for 28 or 365 days. In most cases, rates of decline of the pathogens did not differ significantly between the two inoculum concentrations in the 28-day study. At 6 log CFU/g, populations of all pathogens were reduced by 0.5 to 1.6 log CFU/g during an initial 3-day drying period on both peanuts and pecans. The moisture content of peanuts and pecans remained stable at -24 ± 1 and 22 ± 1°C; at 4 ± 2°C, the moisture content increased from 3.8 to 5.6% on peanuts and from 2.6 to 3% on pecans over 365 days. Pathogen populations were stable on pecans stored under frozen and refrigerated conditions, except for L. monocytogenes, which declined at a rate of 0.03 log CFU/g/30 days at 4 ± 2°C. Salmonella populations were stable on peanuts stored at -24 ± 1 and 4 ± 2°C, but E. coli O157:H7 and L. monocytogenes declined at rates of 0.03 to 0.12 log CFU/g/30 days. At 22 ± 1°C, Salmonella, E. coli O157:H7, and L. monocytogenes declined at a rate of 0.22, 0.37, and 0.59 log CFU/g/30 days, respectively, on peanuts, and at 0.15, 0.34, and 1.17 log CFU/g/30 days, respectively, on pecans. Salmonella counts were above the limit of detection (0.30 log CFU/g) throughout the study. In most cases during storage, counts obtained from pecans were higher than from peanuts.
authors.affiliation: Department of Food Science and Human Nutrition, Citrus Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, 700 Experiment Station Road, Lake Alfred, Florida 33850, USA.
authors.forename: Pardeepinder K
authors.initials: PK
authors.lastname: Brar
authors.affiliation: Department of Food Science and Human Nutrition, Citrus Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, 700 Experiment Station Road, Lake Alfred, Florida 33850, USA.
authors.forename: Lisseth G
authors.initials: LG
authors.lastname: Proano
authors.affiliation: Department of Food Science and Human Nutrition, Citrus Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, 700 Experiment Station Road, Lake Alfred, Florida 33850, USA.
authors.forename: Loretta M
authors.initials: LM
authors.lastname: Friedrich
authors.affiliation: Department of Food Science and Technology, University of California, Davis, One Shields Avenue, Davis, California 95616, USA.
authors.forename: Linda J
authors.initials: LJ
authors.lastname: Harris
authors.affiliation: Department of Food Science and Human Nutrition, Citrus Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, 700 Experiment Station Road, Lake Alfred, Florida 33850, USA. mddanyluk@ufl.edu.
authors.forename: Michelle D
authors.initials: MD
authors.lastname: Danyluk
mesh_terms: D010367:Arachis / Q000382:microbiology*; D031325:Carya / Q000382:microbiology*; D015169:Colony Count, Microbial; D003890:Desiccation; D019453:Escherichia coli O157 / Q000254:growth & development*; D005516:Food Microbiology; D061353:Food Storage; D008089:Listeria monocytogenes / Q000254:growth & development*; D066256:Raw Foods; D012475:Salmonella / Q000254:growth & development*; D013696:Temperature