Process Validation Updates… and a reminder about Food Defense

1. Process Validation Updates…and a reminder about Food Defense Steve Ingham Food Safety Extension Specialist UW-Madison

2. 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

3. 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”

4. 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

5. 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

6. 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

7. 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

8. Accuracy of LAB performance standard in predicting adequate reduction of E. coli O157:H7 during dry-aging

9. Kit for Evaluating Beef Carcass Intervention Treatments

10. LAB culture and Diluent

11. Add diluent to LAB

12. Mix

13. Add LAB solution to sponge

14. Squeeze sponge 10 X

15. Get ready to inoculate brisket

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

17. Inoculate brisket

18. Score sample with sterilized scalpel

19. Peel sample away with sterilized scalpel and forceps

20. “Before” sample is ready to ship

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

22. 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

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

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

25. 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

26. 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)

27. Evaluating slow cook processes: our model system • Unseasoned ground beef • 4 simulated commercial slow-cook schedules

28. Evaluating slow-cook processes • Inoculation studies of 4 cook schedules • each 6 h 45 min. • 25 g ground beef • 9 sampling times each schedule.

29. 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

31. 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. • T = internal temperature • Tr = Reference temperature • Z = reference z value

32. 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

33. Logistic Regression Curve for Predicting 7-log Kill

34. 95% probability of achieving a 7-log reduction of E. coli O157:H7 Heat equivalent to 308 min. at 130oF

35. Tool developmentRepresentative samples

36. A sneak peek at the finished product… • 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

37. Comparison of adequate and inadequate cooking processes 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

38. Next Steps • Seasoned ground beef model system • Model validation with actual roasts • Without seasoning • With seasoning

39. Validating Lethality of Processes for Making Ground & Formed Jerky

40. Jerky Process Lethality Issues • Evaporative cooling • Adaptation of pathogens if drying is before high temperature • Seemingly infinite number of processes being used by processors

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

42. 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

47. Process 1 (Cabela Dehydrator), Hot

48. Process 1 (Cabela Dehydrator), Cold

49. Process 2- no smoke (Alkar smokehouse)

50. Process 2- with smoke (Alkar smokehouse)