Managing Pathogens in Foods: A Post-Harvest Perspective!
John B. Luchansky, Ph.D.Microbial Food Safety Research Unit,
Eastern Regional Research Center,USDA Agricultural Research Service, Wyndmoor, PA 19038
The Agricultural Research Service (ARS) is the Chief Scientific Agency of the
U.S. Department of Agriculture
• 100 Locations, in All 50 States + International Sites
• 2200 Ph.D. Scientists
• 8000 Employees
• >$1 Billion Budget
• $105 Million for Food Safety, 77 Projects + CRADA
ARS National Programs
Animal Production
Animal Health
Arthropod Pests of Animals and Humans
Animal Well-Being and Stress Control Systems
Aquaculture
Plant, Microbial & Insect Germplasm Conservation & Development
Plant Biological & Molecular Processes
Plant Diseases
Crop Protection & Quarantine
Crop Production
Bioenergy & Energy Alternatives
Methyl Bromide Alternatives
Animal Production Nutrition/Safety Natural ResourcesCrop Production
Water Quality & Management
Soil Resource Management
Air Quality
Global Change
Rangeland, Pasture & Forages
Manure & Byproduct Utilization
Integrated Agricultural Systems
Human Nutrition
Food Safety
New Uses, Quality & Marketability of Plant & Animal Products
USDA/ARS – FUNDING FOR FOOD SAFETY
Agricultural Research Service: $102MPre-harvest $60MPost-harvest $42M
Eastern Regional Research Center: $18M~18% of total food safety budget~43% of post-harvest budget
Although the United States maintains one of the safest food supplies in the world…
Per year in the USA • 5,000 deaths• 325,000 hospitalizations• 76 million cases• $5 to $8.4 billion in costs
Total Cases per year in USA
Campylobacter 1,963,000
Salmonella 1,342,000
E. coli 0157:H7 92,500
Listeria monocytogenes 2,000Mead et al., 1999
Incidence of Infection from Pathogens Transmitted through Foods
• Preliminary FoodNet Data --- 10 States, 2008:– Compared to preceding 3 years (2005-2007), the
estimated incidence of Campylobacter, Listeria, Salmonella, STEC O157, and Yersinia did not change significantly.
– By 2008, in comparison with 1996-1998, modeled relative rates of infection decreased by 36% for Listeria, 32% for Campylobacter, and 25% for STEC O157. No significant change for Salmonella.
Morbid. Mortal. Wkly. Rpt.April 10, 2009
Globalization of Food Trade “The World on your Plate”
Herb Butter
Salted buttergarlic pureegarlic saltlemonparsleypepperwater
ChickenBreast Chicken
Batter: FlourWater
Bread Crumbs
Bread crumbRape-seed oil
- Ireland- China, USA, Spain- China, USA, Spain- USA- France, UK- Indonesia- Ireland
- Ireland, BelgiumUK, France etc.
- Belgium, France- Ireland
- Ireland, UK- EU, Australia Eastern Europe
Chicken KievCourtesy A. Reilly, FSAI, Ireland & Gary Ades, USA.
Microbiological Safety Issues Associated with Imported Foods
(George Nychas, 2009)
Sanitation practices for food production, transport and preparation are not universally equivalent worldwide
Importing foods can also move pathogens from where they are indigenous, to where they seldom or do not exist
Imports vs. Exports2001 2002 2003 2004 2005
($ million)
Import 34,115 35,826 40,888 47,234 51,892
Export 37,813 38,569 40,987 44,023 45,851
About 15% of food consumed in USA in 2006 was imported
(www.ers.usda.gov/publications/Agoutlook/AOTables/AOTables.htm)
Mike Doyle, 2008
Globalization of Food Industry
0
2,000,000
4,000,000
6,000,000
8,000,000
10,000,000
12,000,000
1989 1991 1993 1995 1997 1999 2001 2003 2005 2007Fiscal Year
FDA Import Entries Foods OnlyIn 2007, ca. 1% of imported food under FDA jurisdiction
was visually inspected; < 0.5% was tested
Imports totaled >$65 M in 2006
>130,000 foreign food facilities registered by FDA to Export to USA (Ades et al., 2007)
Food Safety Focal Points – Post Harvest
Raw Material
Slaughter FabricateCenters of Excellence in Process
Validation (CEPV)
Process
Finished Product
• Chemical (Na Lactate)• Non-Thermal (RF, PEF, UV)
Interventions• Physical (Cs137, γ-Irradiation)• Biological (LAB, CE, Bacterocins)
Recovery/Characterization• Biosensors (Micro. & Immuno)• Nucleic Acid (PCR, PFGE)• Genomics & Proteomics (Nucleic Acid
Facility)
Modeling• Predictive Microbiology(PMP, ComBase) (Center of
Excellence in Microbial Modeling and Informatics, CEMMI)
Find, Characterize, & Kill
Food Safety – The Big Picture!
Is L. monocytogenes still a concern?
• 2009– Alaska- recalled 872 pounds of sausage product. – Wisconsin- recalled 3,590 pounds of bacon bits.
• 2008– USA
• Total of 14 recalls• 349,660 pounds
– Canada• > 20 products recalled• ~$20 million
USDA/FSIS Public Meeting, Retail Lm Risk Assessment, June 23, 2009
Comparative risk of listeriosis from prepackaged RTE deli meat versus RTE deli meat sliced and packaged at retail
What is the true prevalence of Listeria monocytogenes in RTE meats?
USDA/FSIS Public Meeting, Lm Risk Assessment, June 23, 2009
• 2.8% (31,009) All meat & poultry USDA/FSIS (1990-1999)• 1.6% (32,800) Franks USDA/ARS (2000-2002)• 1.8%(31,700) RTE foods NFPA (2000-2002)• 1.39% (3,518) Deli sliced USDA/ARS/NAFSS (2006)• 0.17% (3,522) Prepackaged slices USDA/ARS/NAFSS (2006)
•Levine et al., JFP 64:1188-1193, 2001.•www.foodsafety.gov/~dms/lmrisk.html•Wallace et al., JFP 66:584-591, 2003.•Gombas et al., JFP 66: April, 2003.
Americans will eat about 7 billion hot dogs this summer!
Sprayed Lethality In Container (“SLIC™”) Method to Deliver Antimicrobials to Surface Contaminated Foods
– Deliver antimicrobial “purge” to packaging container just prior to entry of product• Metered/lower dose of antimicrobial based on
product surface area– Vacuum seal to uniformly distribute
antimicrobials over product surface• Contact time possible throughout shelf life
A patent application has been applied for on this inventionLuchansky et al., Meat Science 71:92-99, 2005
Components of “SLIC”- Antimicrobial with anti-listerial activity
-Lauric arginate ester (LAE) : Mirenat-N or CytogardTM(10% solution of lauric arginate) - Surfactant
- Apparatus to deliver antimicrobial -Modified commercial bagger-Metered commercial sprayer
SLIC® – Sprayed Lethality in Container Technology
•Cheap to install ($5K) & apply ($0.002/lb)•Savings to processor - $0.5-2M per year• Initial 2- 5 log reduction of pathogens
• Less impact on flavor• Lower volume of
antimicrobialapplied/retained
2007 USDA/ARS and 2008 Federal Laboratory Technology Transfer Awards
Meat Science 71:92-99, 2005
SLIC® Technology validated on various meat and poultry products & applicable to other foods
-Lethality and partial inhibition on hams -post process control of L. monocytogenes
-Frankfurters & ham (~5 log decrease)
-Turkey breast (~3 log decrease)
-Roast beef (~2 log decrease)
0
1
2
3
4
5
6
7
8
9
No-0 ppm No-22 ppm Low- Control Low- 22 ppm
Treatments
Log
CFU
/g
Day 0 Day 14 Day 30 Day 45 Day 60 Day 90 Day 120
Lactate/Diacetate combined with SLIC®/LAE to control Lm in frankfurters
Cost effect strategy to achieve Alternative 2 status, and possibly Alternative 1 status, for ensuring the safety of RTE meat and poultry products
Campano et al., RMC - 2009
0.68% Klac + 0.097 NaD22 ppm LAE
High Pressure Processing 200 MPa
For 3’
400 MPa
For 3’
No LAE 0 0.1
LAE (10%)
> 5.4 > 5.4
Water heated at 203°F (95°C) for up to 3 minutes
Validated a ~2.0 log10 reduction
of L. monocytogenes
J. Food Protection 69:39-46, 2006.
Pasteurization Tunnel
– Increased popularity, small producers and small batches• May lack resources to ascertain lethality, appeal FSIS
decisions, and/or provide documentation for HACCP– High and variable pH
• Lack of starter culture, reproducibility– Low temperature fermentation/ripening & drying
• Ambient processing temperatures• Considerable handling
– Extended shelf-life• 12 months soudjouk, 24 months kippered beef & jerky
– Little information on pathogen viability during processing and storage• Association with recalls & illness
Why are Specialty/Ethnic RTE Meats of Concern?
Teewurst
Jerky
Soudjouk
Scrapple
Result: >7.0 log10 CFU reduction of L. monocytogenes, E. coli O157:H7, and SalmonellaImpact: Validated Process Lethality & Shorter time and/or lower temperature saves ~$5K/day
a) 165°F for 2.5 or 3.5 hours - Poultry
b) 180°F for 1.5 or 2.5 hours - BeefHeat/dry Jerky at:
(Porto-Fett et al., J. Food Protection 71:918-926, 2008)(Porto-Fett et al., Poultry Science 88:1275-1281, 2009)
What is Scrapple?• A savory mush of pork trimmings, cornmeal, and
flour with a refrigerated shelf life of ~50 days
• Invented 200 years ago in Chester county, Pennsylvania, by German settlers
• RTE, but reheated for preference by pan frying
• ~6 million pounds (~$15M) consumed in 2008
Question Responses
Do you consider scrapple as RTE?
Yes: 50 (46%); No: 59 (54%)
How thick (cm) do you slice scrapple?
<1 cm: 5 (5%); 1-2 cm: 42 (39 %); 2-3 cm: 41(38%); >3 cm: 21 (19%)
How do you prepare scrapple?
Pan fry: 95 (86%); Bake 7 (6%); Broil 5 (5%);Other 4 (4%)
For how long (minutes) do you cook scrapple?
1-5: 9 (11%); 6-10: 22 (27%); 11-15: 14 (17%);16-20: 14 (17%); >20: 4 (5%); Other: 20 (24%)
Where do you store scrapple?
Refrigerator: 75 (71%); Freezer: 11 (10%);either 20 (19)
Informal Consumer Scrapple Survey
Adekunle et al., J. Food Prot., 2010
Viability of L. monocytogenes on pork scrapple
(N=3; n=3)
Adekunle et al., J. Food Prot., 2010
Re-Heating Pork Scrapple
0
1
2
3
4
5
6
7
8
0 0.5 1 2 3 4
Time (minutes)
Log
CFU
/g
1.3 cm thick 1.9 cm thick
Re-heating for 0.5 to 4.0 min per side reduced pathogen numbers by :
ca. 1.0 to 6.5 log CFU/g for 1.3 cm thick slicesca. 0.7 to 2.1 log CFU/g for 1.9 cm thick slices
Adekunle et al., J. Food Prot., 2010
Talking Points…• Scrapple provides a favorable environment for
growth of L. monocytogenes– high moisture content (70%), high water activity (aw 0.97)
low salt level (1.2%), and a favorable pH (pH 6.4)• Re-heating as practiced by consumers surveyed
eliminates the pathogen• Food grade chemicals being evaluated both “in”
and “on” scrapple for pathogen control
Adekunle et al., J. Food Prot., 2010
“Non-Intact Beef Project”
– 1994 – Ground beef adulterated if contaminated with E. coli O157:H7 (USDA/FSIS)
– January 1999 – Raw non-intact beef adulterated if contaminated with E. coli O157:H7 (USDA/FSIS)
– May 1999 – Publication on translocation and thermal inactivation of E. coli O157:H7 in non-intact beef (Sporing et al., Kansas State)
– January 2002 – Report from National Advisory Committee Microbiological Criteria for Food (NACMCF) on non-intact beef – no added risk, research voids identified
– March 2002 – Comparative risk assessment for intact and non-intact beef (USDA/FSIS)
– October 2003 – NCBA funded research on tenderization and cooking of subprimals (Luchansky et al., ARS, Wyndmoor, PA)
– January 2008 - Formal request from USDA/FSIS to ARS for Non-Intact Beef Research
Genesis
Translocation and Thermal Inactivation of Shiga-toxin Producing Escherichia coli in Non-Intact Beef
Validation of Methods for Blade Tenderization and Cooking
Luchansky et al., 2008. Translocation of surfaceinoculated Escherichia coli O157:H7 into beefsubprimals following blade tenderization. J. FoodProt. 71:2190-2197.
Luchansky, et al., 2009. Thermal inactivation ofEscherichia coli O157:H7 in blade tenderizedbeef steaks cooked on a commercial open-flamegas grill. J. Food Prot. 72:1404-1411.
Luchansky, J. B., 2008. Thermal inactivation of E. coli O157:H7 in blade tenderized beef steaks cooked on a commercial open-flame gas grill. Abstracts of the International Conference of the International Committee on Food Microbiology and Hygiene (ICFMH), Aberdeen, Scotland (PV-15), p383.
Tenderizer in Open Position Showing Blades
Ross TC 7000M(Ross Industries, Midland, VA)
Coring of Subprimals
Diameter: 3.5cmLength: 15cm
USDA Institutional Meat Purchase Spec. #184
1
3
2
7
4
6
5
109
8
Segmentation and Sampling of Cores
Fat side
Lean side
Tenderized side
Cooking and Sampling of Steaks
Baker’s Pride, New Rochelle, NY
S1
S2S3
Q1 Q2
Q3Q4
• Lean vs fat side surface inoculation/tenderization• Single vs double pass tenderization• Five inoculation levels: 0.5, 1.5, 2.5, 3.5, and 6.0 log10 CFU/g• 5-strain cocktail of rifampicin-resistant E. coli O157:H7• 5-strain cocktail of kanamicin-resistant non-O157:H7 STEC• Top-butt beef subprimals purchased at wholesale
- 5 inoculation levels x 4 subprimals per inoculation level x 2 trials per inoculation level x 10 core samples per subprimal x 2 pathogen types = 800 total core samples
• 10 core samples cut into six consecutive segments - Segments 1 to 4 comprised the top four cm of the core- Segments 5 and 6 (and 7) comprised the lowest four cm
“Non-Intact Beef Project”
Recovery of ECOH from segmented core samples of subprimals inoculated with ca. 3.5 log CFU/g
Tenderized subprimalSegment #
ECOH3.19 ± 3.21a
(JFP 71:2190, 2008)
ECOH
% Transfer
1 2.70 ± 2.78 52
2 1.85 ± 2.44 2.0
3 0.35 ± 1.02 0.2
4 -0.8 ± 0.0 0.05
5 0.61 ± 1.22 0.01
6 0.40 ± 1.02 0.3
Total 2.76 54
• Majority of E. coli transferred into segment 1 (52 to 65%)• Linear decrease in pathogen levels from segment 2 to segment 6• Total levels transferred into all six segments ranged from 54 to 67%• Lower starting levels, transfer to all segments, but most in segment 1• Higher starting levels, no greater transfer of cells into deeper tissues
Tenderization + Cooking
•Lean side inoculation/tenderization•Single pass through tenderizer•Steak thickness of 1.0 and 1.5 inch•Cooking at 120° to 160°F internal
Recovery of ECOH (log CFU/g) from non-intact steaks inoculated with a target level of 6.0 log CFU/g that were segmented after cooking
ECOHTemperature (°F)
Thickness(inches)
Total Steak(all strips + all quarters)
0 1 6.44a
1.5 6.08a
120 1 2.32b
1.5 1.88b
130 1 2.58b
1.5 2.15b
140 1 1.93b
1.5 1.99b
150 1 2.15b
1.5 1.72b
160 1 2.50b
1.5 1.52b
• Regardless of thickness of the steak or cooking temperature, there were no statistical differences (P < 0.05) in the extent of thermal inactivation of ECOH in tenderized beef.
• For ECOH, cooking steaks at 120° to 160°F resulted in reductions of ca. 4.0 log CFU/g.
The Road Ahead…• Conduct studies on chemical enhancement of subprimals and
subsequent cooking of steaks• Perform exploratory experiments on treatment of subprimals prior to
tenderization/enhancement• Evaluate combined effects of contact time/temperature and
antimicrobials on blade sanitation as appropriate• Complete growth/inactivation modeling and computer simulations• Validate growth and inactivation models using translocation and
cooking data collected on pilot-scale tenderizer/injector and gas grill
Microbial Food Safety Research UnitFood Product Association Food Safety Award – 2006
International Association for Food Protection
CORE STRENGTHS• Detection/typing of pathogens & threat agents• Genomic and proteomic analyses of pathogens and their
persistence in foods and pathogenicity in hosts• Microbial modeling in food environments• Pilot scale validation of biological, chemical, and thermal
interventions to control pathogens & threat agents during food production, storage, and preparation
Acknowledgments
• Nelly Osoria• Jean Smith• John Cherry• Jennifer Levy• Chun-Wing Yu• Jim Hodges (AMI)• Michelle Rossman (NCBA)• Randy Huffman (Maple Leaf)• Tim Freier (Cargill)• John Sofos (CSU)
• Nate Bauer• Carl Schroeder• Tim Mohr• Heejeong Latimer• Paul Uhler• Bill Shaw• Mimi Sharar• Janell Kause• Mike Doyle (UGA)• Peggy Tomasula (DPPRU)• Randy Phebus (KSU)• Reddi Harshavardan (UNL)
Jeff Call, Anna Porto-Fett, Brad Shoyer, Jean Smith, Alan Oser, & Steve Campano
ERRC Stakeholder
