Process Validation Updates…and a reminder about Food DefenseSteve Ingham

Food Safety Extension Specialist

UW-Madison

Areas of Validation Emphasis

Beef carcass dry-aging interventions Ryan Algino

Slow-cooking of whole-muscle beef roasts Kim Wiegand

Ground & formed beef jerky process lethality Alena Borowski

Shelf-stability of RTE products Darand Borneman

Validating Beef Carcass Dry-Aging – the Microbial Performance Standard E. coli O157:H7 must be undetectable

If slaughter process is hygienic or animal is not a carrier, standard could be met without an intervention

The intervention adds assurance or overcomes slaughter hygiene lapses

There is no specified “log reduction”

Validating Beef Carcass Dry-Aging – the Microbial Performance Standard A practical approach to meeting this

standard: use an intervention that would cause a statistically significant decrease in the number of E. coli O157:H7 cells

Our goal: help you validate your intervention process Show that your intervention would cause a

significant decrease in the number of E. coli O157:H7 cells

Validating Beef Carcass Dry-Aging - Challenges Inoculation studies using pathogens aren’t

possible in plants Dry-aging conditions vary

Weather Size and number of carcasses in cooler Air movement % Relative Humidity Length of dry-aging period

Validating Beef Carcass Interventions – a new approach Inoculate beef carcass with harmless bacteria

that survive the same (or better) compared to E. coli O157:H7 Lactic acid bacteria starter culture = “LAB”

Take a “before” sample Take an “after” sample

How much did levels of LAB decrease? If LAB decrease enough, E. coli O157:H7

would have decreased, too

How much do the LAB levels have to drop? The Least Significant Difference (LSD) for E.

coli O157:H7 in simulated dry-aging studies is 0.3 logs (50% decrease)

This LSD corresponds to an LAB decrease of at least 0.25 logs

Accuracy of LAB performance standard in predicting adequate reduction of E. coli O157:H7 during dry-agingPart Accurate Fail-safe Fail-dangerous

Brisket - fat 15/15 0 0

Brisket – lean 12/15 3/15 0

Heart 12/15 3/15 0

Liver 15/15 0 0

Tongue 13/15 2/15 0

Kit for Evaluating Beef Carcass Intervention Treatments

LAB culture and Diluent

Add diluent to LAB

Mix

Add LAB solution to sponge

Squeeze sponge 10 X

Get ready to inoculate brisket

Inoculate both halves of the carcass One is sampled “before” The other is sampled “after”

Inoculate brisket

Score sample with sterilized scalpel

Peel sample away with sterilized scalpel and forceps

“Before” sample is ready to ship

Ship sample to lab (same way as you ship generic E. coli samples)

The “after” sample

Use dead locks to pin the large template to the second carcass half

Take sample when dry-aging is complete Ship to the lab

Next step:

Determine E. coli O157:H7 LSD and LAB reductions needed to validate acid-spray interventions Acetic acid Lactic acid Fresh Bloom

Predicting the Probability of Achieving a 7-Log Reduction of Escherichia coli O157:H7 During Roast Beef Slow-cooking Processes

Beyond THERM…

Slow cooked beef roasts have unique food safety concerns Temperature abuse growth before cooking? Heat shocked pathogens tougher to kill? Slow come-up times growth before cooking? Salt and spices tougher pathogens?

Need predictive tools to evaluate heat lethality associated with meat processing

Slow-cooking of beef: microbial performance standards 6.5 log reduction in Salmonella USDA recommends no more than 6 h

between 50 and 130°F Besides killing Salmonella, we must also

provide adequate lethality against E. coli O157:H7

We’ve chosen a 7-log lethality target Allows for a small amount of growth before

cooking (0.5 log)

Evaluating slow cook processes: our model system Unseasoned

ground beef 4 simulated

commercial slow-cook schedules

Simulated Cook Schedules

60

70

80

90

100

110

120

130

140

0 60 120 180 200 240 270 300 330 360 390 405

Time (min.)

Set T

empe

ratu

re (d

eg F

)

Commercial Process

Slow come-up time

Fail to reach 130F

Potential heat shock

Evaluating slow-cook processes

Inoculation studies of 4 cook schedules

each 6 h 45 min. 25 g ground beef 9 sampling times each

schedule.

Evaluating slow cook processes Overlaid plates with

MEMB – recover injured cells

Determined cumulative F-value based on time and temperature history

Used E. coli O157:H7 CFU/g plate counts to create model

Cumulative Process Lethality

D-value: number of minutes at constant temperature needed to destroy 90% of organisms

Z-value: change in temperature (°F) needed to change the D-value by 10-fold

Lethal Rate: shown below, equivalent heating rate per minute; expressed for reference temperature.

Cumulative process lethality (F-value): cumulative lethal rate over a given cooking/heating process.

ZTrT

F/)(

10

• T = internal temperature

• Tr = Reference temperature

• Z = reference z value

Logistic Regression Analysis

Z = 10.4°F and Tr = 130°F F-value determined at each sampling point If process was successful, the sample

achieved an E. coli O157:H7 reduction of 7-logs.

Logistic regression used to determine probability of achieving 7-log reduction for any given F-value

0

0.2

0.4

0.6

0.8

1

1.2

100 150 200 250 300 350 400

Lethality

Pr(

7 lo

g r

ed

)Logistic Regression Curve for Predicting 7-log Kill

0

0.2

0.4

0.6

0.8

1

1.2

100 150 200 250 300 350 400

Lethality

Pr(

7 lo

g r

ed)

95% probability of achieving a 7-log reduction of E. coli O157:H7

Heat equivalent to 308 min. at 130oF

Tool developmentRepresentative samples

Lethality <308 Lethality ≥308

E. coli O157:H7 kill

< 7.0 log

113/124 0/20

E. coli O157:H7 kill

≥ 7.0 log 11/124 20/20

A sneak peek at the finished product…

Lethality

0

50

100

150

200

250

300

350

400

450

0 100 200 300 400

Time (min)

F-v

alu

e (m

in)

Core temperature

0

20

40

60

80

100

120

140

160

0 100 200 300 400

Time (min)

Te

mp

era

ture

(F

)

• Easy-to-use Excel worksheet calculations produce two graphs

• Core temperature shows the total cooking process

• Lethality outlines the cumulative lethal rate

• Interpretation for processor: probability that process would attain the 7-log kill

•Above an established F-value (based on temperature and time combination) process has high probability of 7-log kill

Comparison of adequate and inadequate cooking processes

Lethality

0

50

100

150

200

250

300

350

400

450

0 100 200 300 400

Time (min)

F-v

alu

e (

min

)

Lethality

0

50

100

150

200

250

300

350

400

450

0 100 200 300 400

Time (min)

F-va

lue

(min

)

Cooking process not brought up to temperature (e.g. undercooked at 130oF)

Cooking process brought up to 135oF (e.g. rare roast

beef)

Process lethality calculations greatly highlight inadequate cooking processes

Next Steps

Seasoned ground beef model system Model validation with actual roasts

Without seasoning With seasoning

Validating Lethality of Processes for Making Ground & Formed Jerky

Jerky Process Lethality Issues Evaporative cooling Adaptation of pathogens if drying is before

high temperature Seemingly infinite number of processes being

used by processors

Microbial Performance Standards for Jerky-Making 5-log reduction of Salmonella 5-log reduction of E. coli O157:H7 (beef)

Validating Ground & Formed Jerky Process Lethality – a new approach Inoculate jerky mix with harmless bacteria

that survive the same (or better) compared to E. coli O157:H7 and Salmonella Lactic acid bacteria starter culture = “LAB”

Take a “before process” sample Take an “after process” sample

How much did levels of LAB decrease? If LAB decreases enough, pathogens would

have decreased, too

Process 1 (Cabela Dehydrator), Hot

0

1

2

3

4

5

6

7

8

9

10

0 210 420

Time (min)

log

CF

U

Salmonella

E. coli

Saga 200

Biosource

Process 1 (Cabela Dehydrator), Cold

0

1

2

3

4

5

6

7

8

9

10

0 210 420

Time (min)

log

CF

U

Salmonella

E. coli

Saga 200

Biosource

Process 2- no smoke (Alkar smokehouse)

0

1

2

3

4

5

6

7

8

9

10

0 30 90 150 180 210 240

Time (min)

log

CF

U

Salmonella

E. coli

Saga 200

Biosource

Process 2- with smoke (Alkar smokehouse)

0

1

2

3

4

5

6

7

8

9

0 30 150 240

Time (min)

log

CF

U

Salmonella

E. coli

Saga 200

Biosource

Process 3- no smoke (Alkar)

0

1

2

3

4

5

6

7

8

9

10

0 30 45 75 105 135 175

Time (min)

log

CF

U

Salmonella

E. coli

Saga 200

Biosource

Process 3- with smoke (Alkar)

0

1

2

3

4

5

6

7

8

9

0 30 45 175

Time (min)

log

CF

U

Salmonella

E. coli

Saga 200

Biosource

Process 4- no smoke (Alkar)

0

1

2

3

4

5

6

7

8

9

10

0 45 90 150 270

Time (min)

log

CF

U

Salmonella

E. coli

Saga 200

Biosource

Process 4- with smoke (Alkar)

0

1

2

3

4

5

6

7

8

9

0 30 90 180 270

Time (min)

log

CF

U

E. coli

Salmonella

Biosource

Saga 200

Process 5- no smoke (Alkar)

0

1

2

3

4

5

6

7

8

9

10

0 90 150 210 270 330

Time (min)

log

CF

U

Salmonella

E. coli

Saga 200

Biosource

Process 6- no smoke (Alkar)

0

1

2

3

4

5

6

7

8

9

10

0 75 105 180 210

Time (min)

log

CF

U

Salmonella

E. coli

Saga 200

Biosource

How does LAB kill relate to pathogen kill?

Pediococcus spp. Death (logs)

< 4 > 4

E. coli D

eath (logs)

< 5 84 0

> 5 37 51

How does LAB kill relate to pathogen kill?

Pediococcus spp. Death (logs)

< 4 > 4

Salm

onella D

eath

(logs)

< 5 98 1

> 5 23 50

How does LAB kill relate to pathogen kill?

P. acidilactici Death (logs)

< 4 > 4

E. coli D

eath (logs)

< 5 83 3

> 5 32 54

How does LAB kill relate to pathogen kill?

P. acidilactici Death (logs)

< 4 > 4

Salm

onella D

eath

(logs)

< 5 95 5

> 5 20 52

Shelf-stability of RTE meat products Issue is whether Staphylococcus aureus will

grow Pathogen that best tolerates reduced water

activity

Shelf-stability of RTE meat products Gathered wide range of commercial products Made several “substandard” versions of

summer sausage, jerky Inoculated all products Vacuum-packaged Stored at room temperature Monitored S. aureus levels

Where we’re going with this topic Determine algorithm for calculating a shelf-stability score

pH Water activity MPR % Water-Phase Salt

Determine minimum shelf-stability score needed for no S. aureus growth

Develop computer worksheet for processors to enter their product characteristics

Some thoughts on Food Defense Prevention of tampering, terrorism via

commercially processed foods No regulations…yet Do an evaluation and take some basic steps

to prevent problems Info will be on our website:

www.meathaccp.wisc.edu

Need more information or help? Phone me: 608-265-4801 E-mail me: scingham@wisc.edu Check our website:

www.meathaccp.wisc.edu

THANK YOU!