View
218
Download
0
Category
Preview:
Citation preview
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!
Recommended