Impact of WashingDisinfection Methods on Survival of Salmonella in Jalapeno Peppers

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Impact of Washing/Disinfection Methods on
Survival of Salmonella in Jalapeno Peppers

• Kari Jones
• Department of Food Science and Technology

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Jalapeno Pepper Salmonella Outbreak

• 2007-08 -1442 people sickened S. Saintpaul
• 43 states, District of Columbia, Canada
• Uncertified Producer Jalapeno and Serrano Peppers
  mixed with Certified Producer product
• Northern Mexico Producer shipped to McAllen, TX
• Distributed throughout US and Canada

Unsanitary Wash Water
No Clean Water
Certified Plants
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Background

• gt76 Million Cases of Foodborne Illness in U.S.
  Annually
• Industry has NO COMPLETELY effective methods to
  disinfect produce except irradiation (recently
  approved for leafy greens not approved for all
  produce)
• Industry removes 10 to 99 of bacteria and virus.
  
• 10 reduction is 100,000 bacteria to 90,000
• 99 reduction is 100,000 bacteria to 1000

10 to 1000 Salmonella are enough to make a
person sick!!
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Salmonella in Produce Outbreaks1990 to 2005

• 48 of All Produce Outbreaks Salmonella
• Outbreaks Illnesses
• Sprouts 24 1875
• Salad Greens 20 1033
• Melon 16 1137
• Roma Tomato 11 1512
• Potato 14 206
• Import of Produce has doubled in the last 10
  years
• lt1 of produce inspected testing is impractical
  spot contamination, assays take 24 to 48 h
• 625 FDA inspectors for entire U.S.

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Objectives
Since fresh fruits and vegetables are an
important part of a healthy diet, effective
methods are needed both in the home and during
processing at food plants that reduce or
eliminate the threat of Salmonella.

• Determine the optimal method of inoculation for
  consistent recovery of Salmonella from jalapeno
  peppers.
• To compare four washing/disinfection methods and
  two handling methods that would be practical for
  disinfection of produce in the kitchen to
  determine the most effective method of reducing
  counts of Salmonella after disinfection and/or
  washing

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Experimental Procedures

• A. Inoculation and Treatment

1. Inoculum of Salmonella Typhimurium (log 7
CFU/mL) preparation 24 hour culture
(35C) added to 1000 mL 0.1 peptone water 2.
Peppers immersed in inoculum at room temperature
for 2 min 3. Aseptically drained for 30
minutes or until visibly dry. 4. Chemically
treated 5 min at room temperature 5. Peppers
drained aseptically using sterile screens. 6.
Stem and blossom ends were trimmed ca. 15 mm
using a sterile blade
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Experimental Procedure

• B. Dilution and Enumeration

1. Salmonella Recovery and Enumeration
a. Peppers added to 160 ml 0.1 peptone water
b. Macerated using a Stomacher homogenizer for
30 sec at 230 RPM c. Decimal dilutions
prepared in 0.1 peptone water d. Spread
plated onto XLT4 Agar e. Incubated for 48
h at 35 C and enumerated. f. Biochemical
confirmation of Salmonella 2. Treatments
showing no growth were enriched in RV medium for
24 h and plated on XLT4 Agar to recover
non-growing injured cells
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Experimental Design

• Objective One
• Two methods of inoculation were evaluated for
  recovery of Salmonella from jalapeno peppers
• Spot inoculation of 107 CFU over a 1 cm area and
  recovery of Salmonella from the inoculated area.
• Immersion of peppers in a Salmonella inoculum of
  107 CFU/ml in 0.1 peptone water for 2 minutes.
• Enumerate Salmonella from
• Whole Peppers
• Trimmed Peppers 15 mm each end
• Stems and Blossum Ends

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Experimental Design - Objective Two
Treatments (4) Control (no chemical
treatment water only) VeggieWash 2 Citric
Acid/2 Acetic Acid mixture 200 ppm
Chlorine Handling Methods (2) Trimming No
Trimming Replications 3 Randomized Complete
Block Design Statistical Analysis AOV
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Table 1 - Determination of Optimal Inoculation
Method
Immersion
Immersion
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Visual Comparison of 4 Treatments for
Disinfection of Peppers
W
T
W
T
W
T
T
W
Control Water- Washed
2 Citric Acid/2 Acetic Acid
VeggieWash
200 ppm Chlorine
W WHOLE T TRIMMED, SALMONELLA ARE BLACK ON
XLT4 AGAR
ALL COMPARISONS ARE at the SAME DILUTION
w
w
w
w
T
T
T
T
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Table 2. Survival of Salmonella on jalapeno
peppers after chemical treatment and/or trimming.
Log CFU/g Salmonella
Whole Peppers
Trimmed Peppers
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Conclusions

• All treatments significantly (plt 0.05) reduced
  Salmonella in whole peppers
• Washing peppers for five minutes in water
  (control) reduced recovery of Salmonella from log
  7 CFU to log 4.6 CFU/g.
• Trimming and washing in water reduced Salmonella
  to approximately log 1 CFU/g
• Veggie Wash and 2 Acetic Acid/2 Citric Acid
  were quite ineffective since they reduced
  Salmonella on jalapeno peppers by only log 0.5
  CFU/g compared to water.
• 200 ppm Chlorine gave over a one log CFU/g
  reduction in jalapeno peppers

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Significant Findings

• Chlorine (200 ppm) treatment reduced Salmonella
  in trimmed samples to very low (log 0.2 CFU/g) or
  undetectable levels and is an appropriate
  treatment for industry.
• The use of expensive commercial rinses or caustic
  bleach solutions on fresh jalapeno peppers is not
  recommended for kitchen use since simply washing
  and trimming both blossom and stem ends of
  peppers gave a 3 to 5 log CFU/g reduction in
  Salmonella on jalapeno peppers.
• Washing and Trimming Peppers is an Effective
  Method to Reduce the Risk of Salmonellosis from
  Peppers.
• It is essential that the cutting blade be at
  least 15 mm from the contaminated ends to avoid
  recontamination of plant foods and that trimmed
  ends be discarded appropriately to avoid
  recontamination with Salmonella.

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Acknowledgements

• Special thanks to Dr. Ann Draughon, my advisor.
• Appreciation is expressed to the Chancellors
  Honors Program for financial support for this
  research and to the Food Science and Technology
  Department
• Appreciation is expressed to Nathan Miller and
  USDA for photographs used in this presentation.