1. Umass Food Science EXTENSION RESEARCH

2. SANITATION AND VALIDATION OF PRODUCE RINSE WATER TO ENHANCE FOOD SAFETY

3. Monitoring Equipment Chemical Test Kits Chemical Test Strips
Portable ORP and pH Meter
Considerations for Farms
Accuracy
Sensitivity
Time and Patience of handler
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4. Research Objectives
Evaluate the use of portable Oxidation Reduction Potential (ORP) as an indicator of antimicrobial efficacy and as a rapid test method for sanitation management.
Assess Free Chlorine test strips as a rapid test method for postharvest sanitation.
Assess Free Chlorine efficacy on reduction of pathogenic Escherichia coli O157:H7 ATCC suspended in various turbid wash solutions
MA Produce: Cucumbers
Next is the Methods…And …Materials
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5. Methods and Materials

6. Postharvest Process Water Preparation
Synthetic postharvest wash process water was designed to reproduce and simulate small commercial MA farm conditions.
Organic matter: Soil and Cucumber Suspended Solids were diluted with ultrapure water to certain turbidities
Five Autoclaved Process Water solutions:
Clear water: Control
Soil in water
Cucumber Suspended Solids “SS” in water
Soil and Cucumber SS in water
Organic Challenge water
Magnone, Natick Labs 2012
0 ntu
25 ntu ntu CW
Portable HACH 2100Q Turbidimeter

7. Inoculum and Sanitizer Efficacy Procedure
Autoclaved Wash Solutions
100 mL
Clean H2O
(0 NTU)
Soil + H2O
(25, 50 NTU)
Cucumber + H2O
(25, 50 NTU)
Cucumber + Soil
(25, 50 NTU)
Organic Challenge Water
2.5 g/L TOC Tannic acid
& 2.5 g/L TDS Sodium chloride
(5 NTU)
(Exposed for 2 minutes)
Sanitizer Chlorine Treatments
0 ppm NaClO ppm NaClO ppm NaClO
Validate Free Chlorine Levels
E. Coli O157:H7 Inoculation
CFU/mL (Exposed for 2 minutes)
Validate Free Chlorine Levels
Add 100 μl Sodium thiosulfate (1N Na2S2O3) for neutralization
Validate Neutralization
Serial Dilution and Spread Plate onto TSA
Incubation for 24 hours at 37°C
Enumeration

8. Physicochemical Analysis
All physicochemical analysis was conducted according to standard protocols and within manufacturer’s instructions
Organic Challenge Water
2.5 g/L TOC Tannic acid
& 2.5 g/L TDS Sodium chloride
(5 NTU)
Clean H2O
(0 NTU)
Soil + H2O
(25, 50 NTU)
Cucumber + H2O
(25, 50 NTU)
Cucumber + Soil
(25, 50 NTU)
Sanitizer Chlorine Treatments
0 ppm NaClO ppm NaClO ppm NaClO
Record initial ORP (mV) after adding Bleach.
Record ORP (mV) every 30 sec for 8 mins
ORP Analysis
ORP#1
ORP#2
Sample solutions were prepared in parallel for microbial and physicochemical analysis.
Varying types of simulated wash solutions were prepared at varying organic loads to evaluate the QA tools ag water interferences.
Figure 2. Eutech Instruments
OAKTON Handheld ORPTestr 10
Figure 1. Thermo Scientific
Orion Star A221 Portable ORP Meter
Free
Chlorine Analysis

9. Physicochemical Analysis
ORP Analysis
ORP#1
ORP#2
Perform Free Chlorine test strip analysis immediately after ORP.
Within 2 mins. for max Chlorine exposure of 10 mins.
Free Chlorine Analysis
Standard: Free Chlorine compared to HACH DPD colorimetric measurements
“Fr1” WaterWorks Free Chlorine Check Ultra High: #480024
Range: 0, 25, 50, 100, 200, 300, 400, 500, 750 ppm
“Fr2” HF Scientific Free Chlorine MicroCheck: # 09940
Range: 0, 0.05, 0.2, 0.4, 0.6, 0.8, 1.2, 1.5, 2.0, 2.6, 4.0, 6.0,10 ppm
“Fr3” LaMotte Chlorine Test Papers: #4250-BJ
Range: 0, 10, 50, 100, 200 ppm
“Fr1”
“Fr2”
“Fr3”

10. Results

11. Comparison of ORP Measurements with Reduction of E.coli O157:H7
by Chlorine Bleach in Different Turbid Organic Matter Wash Solutions
Wash Solutions
Turbidity (NTU)
NaClO
added (ppm)
Residual
Free Cl
(HACH ppm)
ORP# 1
ORP# 2
E.coli O157:H7
Target: mV
Clean H2O
Control: 0 NTU
444.6
455 +
0 NTU 50
680.7
701 -
Soil + H2O
Control: 50 NTU
475.3
457
25 NTU 25
693.0
700
50 NTU
718.8
717
Cucumber + H2O
Control:50 NTU
350.0
303 11
834.9
830
1.2
584.3
560
Cucumber + Soil
381.0
370 13
761.6
774 10
833.1
816
Organic Challenge H2O
Control:2.5g/L TOC/TDS
220.1
223
2.5 g/L TOC/TDS
209.9
224
200
211.8
210
Results –
Type of simulated wash water impacts the organic matter (influences the residual free chlorine)
when residual free chlorine is present, its an affective sanitizer
Handheld ORP readings of at least 560mV will inactivate E.coli.

12. Comparison of Free Chlorine Test Strips in
Turbid Organic Matter Wash Solutions
Wash Solutions (50 NTU)
Free Chlorine (ppm)
Standard
HACH
Fr1
Fr2
Fr3
Clean H2O
0 ppm
50 ppm 50
> 10
Soil + H2O
25 ppm 25
Between 10-50
Cucumber + H2O
4 ppm
2.0 10
**10 ppm
**< 25
**0.2
**50
Cucumber + Soil
5 ppm
< 25
0.6
Organic Challenge H2O
The presence of free chlorine will active as an effective sanitizer
Presence of high levels of vegetable matter provides inconsistent free cl in some commercial test strips.
Standard: Free Chlorine compared to HACH DPD colorimetric measurements
“Fr1” WaterWorks Free Chlorine Check Ultra High: #480024
Range: 0, 25, 50, 100, 200, 300, 400, 500, 750 ppm
“Fr2” HF Scientific Free Chlorine MicroCheck: # 09940
Range: 0, 0.05, 0.2, 0.4, 0.6, 0.8, 1.2, 1.5, 2.0, 2.6, 4.0, 6.0,10 ppm
“Fr3” LaMotte Chlorine Test Papers: #4250-BJ
Range: 0, 10, 50, 100, 200 ppm

13. Cucumber Matter Affects Free Chlorine Strips Readings
Wash Solutions
Standard HACH
Fr1
Fr2
Fr3
Cucumber + H2O
0 ppm
4 ppm 50
2.0 10
**10 ppm
**< 25
**0.2
**50
Fr1 Fr Fr3
Control
50ppm Free Cl2
Consistent
**Fr1 **Fr **Fr3
Cucumber + H2O
**10ppm Free Cl2
Inconsistent
10ppm <2 5ppm 
10ppm ≠0.2ppm
10ppm ≠ 50ppm

14. Conclusions
Presence of residual Free Chlorine reduced E.coli O157:H7 ATCC suspended in various turbid wash solutions.
Vegetative organic matter can impact Free Chlorine Test strips with inconsistent readings.
Portable ORP meters gave consistent results in controls and organic matter solutions. ORP may be a good indicator of sanitizer activity if kept within mV range.
However high turbid vegetation reduces ORP below threshold
Free Chlorine Test strips are a cheap fast method of rapid method monitoring. However inconsistent readings will occur in high turbid vegetative process water.
ORP correlates well with sanitizer efficacy, but challenging to use as it takes up to 8 minutes for a reading.

15. UMass Work In progress

16. Best Practices for Implementing an On-Farm Food Safety Plan
Documentation
Environmental monitoring
River shed
On-farm facilities
Operators
SOP
Extension Programming

17. Microbial Counts from the CT River
Average MPN and Average E.coli/ Coliform MPN of all water samples taken from the Connecticut River from June 2014 to October 2014.

18. Packing house Drain
Average APC and Coliform Plate Counts for samples taken from drain grate closest to packing area door from June 2014 to October 2014.

19. Average APC and Coliform Plate Counts for samples taken from farm workers hands
August 2014 to October 2014

20. Next Steps Develop and implement SOPs Establish training program
Continue environmental monitoring
Extension Activities
On-line materials
Workshops for best food safety practices

21. Validation of Commercial Produce Sanitizers
Food Safety Validation
Lab analysis
Physiochemical
Microbiological
Organoleptic attributes
Operational implementation
Dosage calculations
Cost per use
Extension Dissemination

22. On Farm Research Needs Diagnostic tools that can support QA on-farm
Must Account for Resource Limitations
Ease of use:
No/little sample preparation
No/little technical skills
Account for the farming conditions
Limited electricity
Affordable
Rapid
i.e. Agricultural water cannot be used unless the issue has been resolved

23. Natural Antimicrobials for Produce Safety
Strategy:
Natural
Non-thermal
highly effective antimicrobial
Science
Physiochemical emulsion stability
Antimicrobial activity
Product Development for application
Figure 3: Food-grade antimicrobial emulsions can be formed using a simple spontaneous emulsification method
food-grade antimicrobial emulsions as a non-thermal, potent, and safe means of combating pathogens associated with fresh and fresh-cut produce

24. Biosensors for Agricultural Water
Figure 1: The bacteriophage will be used to recognize, infect and replicate within Salmonella spp. cells. Once replication is complete, the replicated bacteriophage will burst out of the bacteria. The increase in bacteriophage numbers can then be quantified with a fluorescent dipstick.
Nugen, S. Bacteriophage Technology, CPS proposal, 2014.

26. Phage Amplification + =
FDA approved key path