Gordon Davidson UC Davis Conducting a Validation * * Assess and improve current systems Assemble the Validation Team Determine the most resistant pathogen Validate the efficacy of the lethal process Conduct a hazard analysis Identify preventive control(s) for hazards reasonably likely to occur Consider the level of inactivation needed Assess the impact of the food matrix Define specific equipment and operating parameters Prevent recontamination Adapted from: AIOE,
Identifying the Most Significant Pathogens of Public Health Concern Reasonably likely to occur Epidemiology Outbreaks, recalls, surveys # of Cases Ecology Production/processing Product (intrinsic factors) Product How is it handled? How is it prepared and consumed? What is the shelf life? Oct 8 Nov Dec 7 Jan Feb Apr May Jun WEEK Recalls involving U.S. product Salmonella almonds (, ), hazelnuts (9, ), macadamia (9,, ), pecans (9, ), inshell pistachios (9,, ) E. coli O7:H7 hazelnuts (), walnuts () Listeria monocytogenes walnuts (9)
Outbreaks tree nuts Salmonellosis Almonds raw (U.S. source) -, Canada/U.S. -, U.S./Canada, Sweden Almonds - raw (Australia source), Australia Pine nuts - raw (Turkey), U.S. Pistachios - raw and roasted? (U.S.) 9 ( case),, U.S. Coconut (dried) (??) 999, United Kingdom E. coli O7:H7 gastroenteritis Inshell hazelnuts (U.S.), US/Canada Walnuts raw (U.S.), Canada (linked) www.ucfoodsafety.ucdavis.edu
Recalls extracted from: http://ucfoodsafety.ucdavis.edu/files/.pdf
CA Pistachios: Sinker and Floater Streams Recent average harvest per year = million pounds Floaters (~%) Sinkers (~8%) 7 7 8 8 Inshell Kernel Shell Inedible Kernel Prevalence of Salmonella in CA pistachios Weighted average (assuming % floaters and 8% sinkers).%.% Floaters Sinkers.%.% Weighted Average (prevalence).7%.%.% Percent Positive (- g Samples).%.%.% YR Average.% Average Year v Disproportionately high number of floaters were tested in and v A weighted average was calculated assuming 8% sinker/% floater
Frequency (# observations) 8 Levels of Salmonella in pistachios,, combined Floater Samples Sinker Samples 8 < < < < <8 8 < < < MPN per, g MPN per, g MPN = Most Probable Number Salmonella in raw pistachios positive samples of,98 7 Salmonella isolates 9 serovars S. Enteritidis ( types), S. Liverpool, S. Motevideo, S. Senftenberg, S. Tennessee, S. Worthington Reason for higher prevalence in floaters is being investigated
Identifying Most Significant Pathogens of Public Health Concern Reasonably likely to occur Epidemiology Outbreaks, recalls, surveys Ecology Production/processing Product (intrinsic factors) Product How is it handled? How is it prepared and consumed? What is the shelf life? E. coli O7:H7 Listeria monocytogenes Salmonella Potential exposure of pistachios to human pathogens Harvest Nuts mixed with tree debris during harvest High moisture at harvest Delay in hulling or post-hulling drying of > hours could lead to increases in microorganisms on the hulls Hulling Floaters and Sinkers separated in water Water may facilitate spread contamination Storage Drying in silos with unfiltered ambient air 7
// Post Harvest Treatment Options Traditional methods Steam/Heat Oil Roasting Dry Roasting Propylene Oxide Almonds Pistachios Walnuts Almonds Pistachios* Walnuts* Almonds Pistachios Walnuts* Almonds Pistachios Walnuts *Not Common *Not common Potential Preventive Controls Process Equipment Baking Blanching Dehydration Drying Dry Roasting Infrared Oil Roasting PPO Radio Frequency Steaming Dehydrators Continuous Batch Preconditioners Propylene Oxide Chamber Roasters (often continuous) Rotary Flatbed Oil Steam tunnels Vacuum/heat Adapted from: AIOE, 8
Treatment of pistachios 9% of domestic shipments from California facilities are treated by one or more pathogen reduction steps The rest are shipped labeled raw agricultural product Raw pistachios in the marketplace means not roasted Most are treated by steam or vacuum treatments 7 Pistachio properties Level of microbial reduction significantly impacted by: Product properties (intrinsic properties) A w (. to.) Moisture ( to 7%) Composition (fat (%), protein (%), carbohydrates (8%) Size, shape Surface properties Skin, shell 9
Survival during storage at - C (triangle) and C (square) on non-selective agar Log CFU/g Salmonella spp. E. coli O7:H7 L. monocytogenes Time (days) Time (days) Time (days) No decline over months Kimber et al., Survival during storage at C on nonselective (closed diamond) and selective (open diamond) agars Limit of Detection (dashed line) Log CFU/g Salmonella spp. E. coli O7:H7 L. monocytogenes Time (days) Time (days) Time (days) Kimber et al.,
// Most resistant pathogen Microorganisms of public health concern Reasonably likely to occur Process(es) Pathogen(s) most resistant to process May differ by process Salmonella For low moisture foods AT THIS TIME Salmonella is generally accepted as the most resistant pathogen (desiccation tolerance, history, epidemiology) Research underway to validate this assumption Salmonella is more resistant than E. coli O7:H7 on almonds during desiccation and heating in oil at C/ F for min or dry heating (laboratory) at C/7 F for min 9 8 Reduction 7 log CFU/g Days OilHot Roasting Oil Dry DryRoasting Oven desiccation n Salmonella Enteritidis PT n E. coli O7:H7 99 apple cider outbreak n E. coli O7:H7 spinach outbreak
Center for Produce Safety Grant Starting January Objective. To determine the impact of pistachio moisture and nut form (kernel or inshell) on the heat sensitivity of Salmonella, E. coli O7:H7, L. monocytogenes, and E. faecium NRRL B- inoculated pistachios. Evaluation of Salmonella isolates from pistachios Salmonella and other pathogens are MORE RESISTANT to processes when in or on low water activity foods like tree nuts Resistance to destruction Low a W Foods Salmonella
Next up Dr. Michelle Danyluk Most resistant pathogens: selection and use of surrogates