Efficacy of Produce Wash Product: Use of Fresh Potatoes as Model System for Evaluating Pathogen Cont

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Efficacy of Produce Wash Product Use of Fresh
Potatoes as Model System for Evaluating Pathogen
Control in Produce Processing

• Peter Gray, Dong-Hyun Kang. Department of Food
  Science and Human Nutrition, Washington State
  University, Pullman, WA 99164-6376
• Jeff Kronenberg. Department of Food Science
  Toxicology, University of Idaho, Moscow, ID
  83844-2312

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Foodborne Illness in the USA(Source CDC)

• 76 million illnesses every year
• Results in 300,000 hospitalizations
• Causes 5,000 deaths
• Increasing incidence of STEC O157 infections
  traced to fresh produce, while those related to
  meats decreasing

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Outbreak-Associated Cases of Foodborne Illness
(CDC) - 2006

• 1 STEC O157 outbreak (32 confirmed cases) traced
  to spinach
• 2 STEC O157 outbreaks (14 confirmed cases) traced
  to lettuce
• Multistate outbreak of Salmonella Typhimurium (58
  confirmed cases) traced to tomatoes
• Outbreak of Salmonella Newport (37 confirmed
  cases) traced to tomatoes

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Escherichia coli O157H7 Outbreak traced to raw
spinach from Salinas Valley, California, 2006.
199 cases in 26 states (CDC)
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Salmonella Typhimurium Outbreak traced to
tomatoes, 183 cases in 21 states, 2006 (FDA)
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Bacterial Soft Rot of Potatoes

• Caused by Gram-negative bacterium Pectobacterium
  carotovorum ssp. carotovorum (formerly classified
  as Erwinia cartovora ssp. carotovora)
• Dissolves middle lamella (intercellular cement),
  causing vegetables to liquify

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Search for Effective Produce Sanitizers

• Must be effective in wash flumes and dip tanks
  under a wide variety of water conditions
• Increasing consumer demand for effective but
  safe, natural, environmentally-friendly
  disinfectants

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HealthPro Brands FIT Fruit and Vegetable Wash

• Produce cleaner and antibacterial agent
• Ingredients citric acid, sodium lauryl sulfate,
  grapefruit oil extract, sodium carbonate. All FDA
  GRAS.
• Very safe and easy to store, handle, and prepare
  available to general public
• Used at pH 3.0 5 g/L powdered formulation, 1128
  (vv) liquid formulation
• WSU Sensory panel detected no off-flavors in
  FIT-treated baked potatoes

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Chlorine Dioxide (ClO2)

• Approved for use on fresh fruits and vegetables
• Hazardous ingredients (sodium chlorite,
  hydrochloric acid, sodium hypochlorite)
• Hazardous to store and prepare
• Personal protective gear required
• Commonly used at 5 ppm free ClO2
• ClO2 produces no toxic by-products or off-flavors
  in produce

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FIT Testing Protocol Fresh Pack Potato Operation

• Assay for aerobic plate count (bacterial
  microflora) and Gram negative bacteria (indicator
  of enteric human pathogens and Pectobacterium
  soft rot)
• Flume washed potatoes powdered FIT, untreated
  water control
• Spray bar treated potatoes liquid FIT, 9 ppm
  ClO2, untreated water control

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Reduction of Gram Negatives, APC in Fresh Pack
Potato Tubers
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Reduction of Gram Negatives, APC in Fresh Pack
Potato Flume Water
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Sanitizer Evaluations Utilizing Bacterial
Suspensions in Vitro

• Chemicals powdered FIT, liquid FIT, 9 ppm ClO2,
  water control
• Bacteria suspended in treatment solutions,
  enumerated at selected intervals
• E. coli O157H7, S. Typhimurium, P. carotovorum
  ssp. carotovorum tested
• Both deionized and potato flume water evaluated

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Reduction of Escherichia coli O157H7 in Vitro
Using Deionized Water Treated With Sanitizers
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Reduction of Salmonella Typhimurium in Vitro
Using Deionized Water Treated with Sanitizers
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Reduction of Pectobacterium carotovorum ssp.
carotovorum in Vitro Using Deionized Water
Treated with Sanitizers
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In Vitro Trials Using Sterile Flume Water From
Fresh Pack Potato Operation

• 330 mg/L total dissolved solids
• 2,186 mg/L total suspended solids
• Water containing soil particles, potato tissues
  present serious challenges to sanitizers

Flume water (left), deionized (right)
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Reduction of Escherichia coli in Vitro Using
Flume Water Treated with Sanitizers
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Reduction of Salmonella Typhimurium in Vitro
Using Flume Water Treated with Sanitizers
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Reduction of Pectobacterium carotovorum ssp.
carotovorum in Vitro Using Flume Water Treated
with Sanitizers
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Tests on Inoculated Potato Tubers

• E. coli O157H7, S. Typhimurium inoculated onto
  unwashed tubers and dried
• Treatments prepared with flume water
• Tubers agitated in treatment solutions, removed
  at selected intervals, enumerated
• Treatments
• FIT (powdered and liquid formulations)
• 9 ppm ClO2
• Flume water control

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Reduction of Escherichia coli O157H7 on
Inoculated Potatoes
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Reduction of Salmonella Typhimurium on Inoculated
Potatoes
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Tests on Uninoculated Potato Tubers

• Unwashed, uninoculated tubers agitated in
  treatment solutions, removed at selected
  intervals, enumerated
• Aerobic Plate Count (APC)
• Yeasts
• Molds

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APC of Uninoculated Potato Tubers in Flume Water
Treated With Sanitizers
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Yeast Microflora of Uninoculated Potato Tubers in
Flume Water Treated With Sanitizers
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Mold Microflora of Uninoculated Potato Tubers in
Flume Water Treated With Sanitizers
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Conclusions Potato Wash Water

• FIT highly effective (gt6 log reduction in 30 sec)
  against cell suspensions of enteric pathogens and
  P. carotovorum ssp. carotovorum under all water
  conditions tested
• Limited APC reduction, possibly due to
  acid-resistant yeasts and molds
• ClO2 effective only in low solids water
• FIT has significant potential for preventing
  cross-contamination of pathogens in flumes and
  dip tanks with high soil loading

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Conclusions Potato Tuber Tests

• Low impact from both disinfectants
• In lab tests FIT reduced enteric pathogens by
  1.4-1.8 log but only after 5 min ClO2 resulted
  in lt0.9 log reduction
• In lab tests FIT reduced APC, yeasts, molds by
  0.8 1.2 log ClO2 was no more effective than
  water control
• Potato tubers represent challenges due to heavy
  soils, lenticels, other surface features
• More research needed involving other vegetable
  models

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Acknowledgements

• Todd Wichmann, HealthPro Brands, Inc. of
  Cincinnati, Ohio
• Wada Farms Marketing Group, LLC. Of Pingree,
  Idaho
• International Dioxide, Inc. of North Kingstown,
  Rhode Island