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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
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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
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
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
Escherichia coli O157:H7 Outbreak traced to raw spinach from Salinas Valley, California, 2006. 199 cases in 26 states(CDC)
Salmonella Typhimurium Outbreak traced to tomatoes, 183 cases in 21 states, 2006 (FDA)
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
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
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, 1:128 (v:v) liquid formulation WSU Sensory panel detected no off-flavors in FIT-treated baked potatoes HealthPro Brands FIT® Fruit and Vegetable Wash
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
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
Reduction of Gram Negatives, APC in Fresh Pack Potato Tubers
Reduction of Gram Negatives, APC in Fresh Pack Potato Flume Water
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 O157:H7, S. Typhimurium, P. carotovorum ssp. carotovorum tested • Both deionized and potato flume water evaluated
Reduction of Escherichia coli O157:H7 in Vitro Using Deionized Water Treated With Sanitizers
Reduction of Salmonella Typhimurium in Vitro Using Deionized Water Treated with Sanitizers
Reduction of Pectobacterium carotovorum ssp. carotovorum in Vitro Using Deionized Water Treated with Sanitizers
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)
Reduction of Escherichia coli in VitroUsing Flume Water Treated with Sanitizers
Reduction of Salmonella Typhimurium in Vitro Using Flume Water Treated with Sanitizers
Reduction of Pectobacterium carotovorum ssp. carotovorum in Vitro Using Flume Water Treated with Sanitizers
Tests on Inoculated Potato Tubers • E. coli O157:H7, 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
Reduction of Escherichia coli O157:H7 on Inoculated Potatoes
Tests on Uninoculated Potato Tubers • Unwashed, uninoculated tubers agitated in treatment solutions, removed at selected intervals, enumerated • Aerobic Plate Count (APC) • Yeasts • Molds
APC of Uninoculated Potato Tubers in Flume Water Treated With Sanitizers
Yeast Microflora of Uninoculated Potato Tubers in Flume Water Treated With Sanitizers
Mold Microflora of Uninoculated Potato Tubers in Flume Water Treated With Sanitizers
Conclusions – Potato Wash Water • FIT highly effective (>6 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
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 <0.9 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
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