title: A dry-inoculation method for nut kernels.
abstract: A dry-inoculation method for almonds and walnuts was developed to eliminate the need for the postinoculation drying required for wet-inoculation methods. The survival of Salmonella enterica Enteritidis PT 30 on wet- and dry-inoculated almond and walnut kernels stored under ambient conditions (average: 23 °C; 41 or 47% RH) was then compared over 14 weeks. For wet inoculation, an aqueous Salmonella preparation was added directly to almond or walnut kernels, which were then dried under ambient conditions (3 or 7 days, respectively) to initial nut moisture levels. For the dry inoculation, liquid inoculum was mixed with sterilized sand and dried for 24 h at 40 °C. The dried inoculated sand was mixed with kernels, and the sand was removed by shaking the mixture in a sterile sieve. Mixing procedures to optimize the bacterial transfer from sand to kernel were evaluated; in general, similar levels were achieved on walnuts (4.8-5.2 log CFU/g) and almonds (4.2-5.1 log CFU/g). The decline of Salmonella Enteritidis populations was similar during ambient storage (98 days) for both wet-and dry-inoculation methods for both almonds and walnuts. The dry-inoculation method mimics some of the suspected routes of contamination for tree nuts and may be appropriate for some postharvest challenge studies.
authors.affiliation: Department of Food Science and Technology, University of California, Davis, Davis, CA 95616-8598, USA.
authors.forename: Tyann
authors.initials: T
authors.lastname: Blessington
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Theofel
authors.forename: Linda J
authors.initials: LJ
authors.lastname: Harris
mesh_terms: D001431:Bacteriological Techniques / Q000379:methods*; D003257:Consumer Product Safety; D005506:Food Contamination / Q000032:analysis*; D005516:Food Microbiology; D005519:Food Preservation; D031324:Juglans / Q000737:chemistry / Q000382:microbiology*; D050296:Microbial Viability; D009754:Nuts / Q000737:chemistry / Q000382:microbiology*; D027861:Prunus / Q000737:chemistry / Q000382:microbiology*; D012477:Salmonella enteritidis / Q000254:growth & development*; D013696:Temperature; D014867:Water / Q000032:analysis
chemical_list: D014867:Water