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Multiple Hurdle Interventions Against E. coli O157:H7 in Apple Cider

Multiple Hurdle Interventions Against E. coli O157:H7 in Apple Cider. Steve Ingham University of Wisconsin-Madison. Wisconsin’s Cider Safety Extension Team. Teryl Roper - growers Steve Ingham - processors Barbara Ingham - consumers. Apple Cider/ E. coli O157:H7 Research Topics.

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Multiple Hurdle Interventions Against E. coli O157:H7 in Apple Cider

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  1. Multiple Hurdle Interventions Against E. coli O157:H7 in Apple Cider Steve Ingham University of Wisconsin-Madison

  2. Wisconsin’s Cider Safety Extension Team • Teryl Roper - growers • Steve Ingham - processors • Barbara Ingham - consumers

  3. Apple Cider/E. coli O157:H7 Research Topics • Lethality of freeze/thaw treatment • Multiple hurdle interventions • Other pathogens of concern • Useful indicator organisms

  4. Lethality of Freeze/Thaw against E. coli O157:H7 in Apple Cider • pH 3.5 cider, 10 ml/bottle, heat-sterilized • two test strains • -20º C, 24 h to freeze • thaw at 4ºC, 23ºC, or 10 sec in microwave • 0.69 - 3.43 log kill (TSA plating) • 1.39 - 5.64 log kill (SMA plating)

  5. A New Intervention Paradigm • Organic acids more lethal at warm temperatures • Immediate refrigeration is NOT best for cider safety • Short-term storage at 25 - 45ºC to kill pathogens

  6. Multiple Hurdle Protocol # 1 • Heat-sterilized ciders; pH 3.3, 3.7, 4.1 • 7-log, “cocktail” inoculum • enumeration of survivors by plating • freeze/thaw • sorbic acid = SA (0.1%) • short-term storage at 4, 25, or 35ºC

  7. 5-log kill of E. coli O157:H7 in pH 3.3 Cider • 6h at 35ºC • Freeze/thaw 4.0 ml, -20ºC for 48 h, then 4ºC for 4 h

  8. 5-log kill of E. coli O157:H7 in pH 3.7 Cider • 6 h at 4ºC + freeze/thaw • 2 h at 25ºC + freeze/thaw • 1 h at 35ºC + freeze/thaw • 6 h at 35ºC • 0.1% SA + 12 h at 25ºC

  9. 5-log kill of E. coli O157:H7 in pH 4.1 Cider • 6 h at 35ºC + freeze/thaw • 0.1% SA + 12 h at 25ºC + freeze/thaw • 0.1% SA + 4 h at 35ºC + freeze/thaw • 0.1% SA + 6 h at 35ºC

  10. Taste Panels • 6 h at 35ºC preferred over pasteurized • freeze/thaw preferred over pasteurized • 6 h at 35 C + freeze/thaw preferred over pasteurized

  11. Taste Panels • 0.1% SA + 6 h at 35 C NOT preferred over pasteurized • 0.1% SA + 6 h at 35 C + freeze/thaw NOT preferred over pasteurized

  12. Multiple Hurdle Protocol # 2 • Irradiation-sterilized ciders (3), pH adjusted to 3.3, 3.5, 3.7, 3.9, 4.1 • Potassium sorbate = SA (0.05, 0.1%) sodium benzoate = BA (0.05, 0.1%) • Short-term storage at 5, 15, 25 35, 45ºC • Freeze/thaw • Growth/no growth broth assay for 5-log kill

  13. Protocol #2: 5-log Kill of E. coli O157:H7 • pH 3.3 + 0.1% SA or BA + 6 h at 35ºC • pH 3.3 - 3.7 + 0.1% SA or BA + 6 h at 45ºC • pH 3.9 + 0.1% BA + 6 h at 45ºC • pH 3.3 + 0.1% BA + 4 h at 25ºC + freeze/thaw • pH 3.3 + 0.1% SA + 12 h at 25ºC + freeze/thaw

  14. Protocol #2: 5-log Kill of E. coli O157:H7 • pH 3.3 + 0.1% SA + 4 h at 35ºC + freeze/thaw • pH 3.3 + 0.1% BA + 2 h at 35ºC + freeze/thaw • pH 3.3 + 0.05% SA or BA + 6 h at 35ºC + freeze/thaw • pH 3.7 - 4.1 + 0.1% BA + 4 h at 45ºC + freeze/thaw

  15. Other Bacterial Pathogens of Possible Concern in Apple Cider • Salmonella typhimurium DT104: intermediate survival in unpasteurized cider; will not survive treatments that are effective against E. coli O157:H7 • Listeria monocytogenes: poor survival in unpasteurized cider; not an appropriate target pathogen

  16. Potential Indicator Organisms for Evaluating Sanitation • Generic E. coli: survives well in refrigerated cider • Coliforms: more prevalent, but problem with possible non-fecal origin • Enterococcus spp.: survive poorly in refrigerated cider

  17. Testing for Indicator Organisms • Drop apples more likely to contain generic E. coli; apple rinse testing may be useful • Wash water can become a contamination step; testing here is appropriate • Test cider quickly; neutralize or dilute it before testing • Coliform kits vary widely in performance

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