efficacy of produce wash product: use of fresh potatoes as model system for evaluating pathogen...
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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 USAFoodborne Illness in the USA(Source: CDC)(Source: CDC)
76 million illnesses every yearResults in 300,000 hospitalizationsCauses 5,000 deathsIncreasing incidence of STEC O157
infections traced to fresh produce, while those related to meats decreasing
Outbreak-Associated Cases of Outbreak-Associated Cases of Foodborne Illness (CDC)Foodborne Illness (CDC) - 2006- 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 PotatoesBacterial Soft Rot of Potatoes•Caused by Gram-negative bacterium Caused by Gram-negative bacterium Pectobacterium Pectobacterium carotovorumcarotovorum ssp. ssp. carotovorumcarotovorum (formerly classified as (formerly classified as Erwinia cartovora Erwinia cartovora sspssp. carotovora. carotovora))•Dissolves middle lamella (intercellular cement), causing Dissolves middle lamella (intercellular cement), causing vegetables to liquifyvegetables to liquify
Search for Effective Produce Search for Effective Produce SanitizersSanitizers
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
HealthPro Brands FIT® Fruit and HealthPro Brands FIT® Fruit and Vegetable WashVegetable 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, 1:128 (v:v)
liquid formulation WSU Sensory panel detected no off-flavors in FIT-treated
baked potatoes
Chlorine Dioxide (ClOChlorine Dioxide (ClO22))
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 FIT Testing Protocol – Fresh Pack Potato OperationPotato 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
Effect of FIT, ClO2, Water Control on Potato Tuber Microbial Populations
0
2
4
6
8
Spray BarWater
Spray BarClO2
Spray BarFIT
FlumeWater
Flume FIT
Log 1
0 C
FU
/Tub
er
Gram Neg
APC
Reduction of Gram Negatives, APC in Fresh Pack Potato Tubers
Reduction of Gram Negatives, APC in Fresh Pack Potato Flume Water
Effect of FIT, Water Control on Microbial Populations of Potato Flume Wash Water
5.95
0
7.24
5.81
0
2
4
6
8
Flume Water Wash Flume FIT Wash
Log 1
0 C
FU
/ml
Gram Neg
APC
Sanitizer Evaluations Utilizing Bacterial Suspensions in Vitro
Chemicals: powdered FIT, liquid FIT, 9 Chemicals: powdered FIT, liquid FIT, 9 ppm ClOppm ClO22, water control, water control
Bacteria suspended in treatment solutions, Bacteria suspended in treatment solutions, enumerated at selected intervalsenumerated at selected intervals
E. coliE. coli O157:H7, O157:H7, SS. Typhimurium, . Typhimurium, PP. . carotovorumcarotovorum ssp. ssp. carotovorum carotovorum testedtested
Both deionized and potato flume water Both deionized and potato flume water evaluatedevaluated
In Vitro Reduction of E. coli O157:H7 by Sanitizers Prepared in Deionized Water
0
1
2
3
4
5
6
7
8
0 0.5 1 3 5Min
Log 1
0 C
FU
/ml
Water
Dry FIT (5g/ L)
Liquid FIT (1:128)
9 ppm ClO2
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
In Vitro Reduction of S . Typhimurium by Sanitizers Prepared in Deionized Water
0
1
2
3
4
5
6
7
8
0 0.5 1 3 5Min
Lo
g10
CF
U/m
l
Water
Dry FIT (5g/ L)
Liquid FIT (1:128)
9 ppm ClO2
Reduction of Pectobacterium carotovorum ssp. carotovorum in Vitro Using Deionized Water
Treated with Sanitizers
In Vitro Reduction of Pectobacterium carovorum ssp. carotovorum by Sanitizers Prepared in Deionized
Water
0
1
2
3
4
5
6
7
8
0 0.5 1 3 5Min
Lo
g1
0 C
FU
/ml
Water
Dr y FIT (5g/ L)
Liquid FIT (1:128)
9 ppm ClO2
•330 mg/L total dissolved solids
•2,186 mg/L total suspended solids
•Water containing soil particles, potato tissues present serious challenges to sanitizers
In Vitro Trials Using Sterile Flume Water From Fresh Pack Potato Operation
Flume water (left), deionized (right)
In Vitro Reduction of E. coli O157:H7 by Sanitizers Prepared in Flume Water
0
1
2
3
4
5
6
7
8
0 0.5 1 3 5
Min
Lo
g10
CF
U/m
l
Water
Dry FIT
Liquid FIT
9 ppm ClO2
Reduction of Escherichia coli in Vitro Using Flume Water Treated with Sanitizers
Reduction of Salmonella Typhimurium in Vitro Using Flume Water Treated with Sanitizers
In Vitro Reduction of S. Typhimurim by Sanitizers Prepared in Flume Water
0
1
2
3
4
5
6
7
8
0 0.5 1 3 5
Min
Lo
g10
CF
U/m
l
Water
Dry FIT
Liquid FIT
9 ppm ClO2
Reduction of Pectobacterium carotovorum ssp. carotovorum in Vitro Using Flume Water Treated
with Sanitizers
In Vitro Reduction of Pectobacterium carotovorum ssp. carotovorum by Sanitizers Prepared in Flume
Water
01
23
45
67
8
0 0.5 1 3 5Min
Lo
g10
CF
U/m
l
Water
Dry FIT
Liquid FIT
9 ppm ClO2
Tests on Inoculated Potato TubersTests 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, enumeratedTreatments FIT (powdered and liquid formulations) 9 ppm ClO2
Flume water control
Effect of Sanitizers on E. coli O157:H7-Inoculated Potato Tubers
0
2
4
6
8
10
0 0.5 1 3 5
Time, Min
Lo
g10
CF
U/t
ub
er
Control
Dry FIT pH 3.0
Liq FIT pH 3.0
ClO2 9 ppm
Reduction of Escherichia coli O157:H7 on Inoculated Potatoes
Reduction of Salmonella Typhimurium on Inoculated Potatoes
Effect of Sanitizers on S . Typhimurium-Inoculated Potato Tubers
0
2
4
6
8
10
0 0.5 1 3 5
Time, Min
Lo
g10
CF
U/t
ub
er
Control
Dry FIT pH 3.0
Liq FIT pH 3.0
ClO2 9 ppm
Tests on Uninoculated Potato TubersTests on Uninoculated Potato Tubers
Unwashed, uninoculated tubers agitated in treatment solutions, removed at selected intervals, enumerated
Aerobic Plate Count (APC)YeastsMolds
Effect of Sanitizers on APC of Potato Tubers
0
2
4
6
8
10
0 0.5 1 3 5
Time, Min
Lo
g10
CF
U/t
ub
er
Control
Dry FIT pH 3.0
Liq FIT pH 3.0
ClO2 9 ppm
APC of Uninoculated Potato Tubers in Flume Water Treated With Sanitizers
Yeast Microflora of Uninoculated Potato Tubers in Flume Water Treated
With SanitizersEffect of Sanitizers on Yeast Microflora of Potato Tubers
0
2
4
6
8
10
0 0.5 1 3 5
Time, Min
Lo
g10
CF
U/t
ub
er
Control
Dry FIT pH 3.0
Liq FIT pH 3.0
ClO2 9 ppm
Mold Microflora of Uninoculated Potato Tubers in Flume Water Treated
With SanitizersEffect of Sanitizers on Mold Microflora of Potato
Tubers
0
2
4
6
8
10
0 0.5 1 3 5
Time, Min
Lo
g10
CF
U/t
ub
er
Control
Dry FIT pH 3.0
Liq FIT pH 3.0
ClO2 9 ppm
Conclusions – Potato Wash WaterConclusions – 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 TestsConclusions – 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
AcknowledgementsAcknowledgements
Todd Wichmann, HealthPro Brands, Inc. of Cincinnati, Ohio
Wada Farms Marketing Group, LLC. Of Pingree, Idaho
International Dioxide, Inc. of North Kingstown, Rhode Island