Formulating Foods for Microbiological Safety

1. Formulating Foods for Microbiological Safety Kathleen Glass, Ph.D. Assistant Scientist Food Research Institute University of Wisconsin-Madison President-Elect International Association for Food Protection BAFP 21 November 2003 Florianópolis Brasil

2. Formulation-safe foods • Definition of low acid (canned) foods • Risks to consider • Strategies to formulate safe foods • Refrigerated foods • Shelf-stable foods • Convenience foods • Meet changing needs of consumers “on the go”

3. Low acid foods • pH > 4.6 and aw >0.85 • Considered potentially hazardous if not refrigerated • United States: Low Acid Canned Foods • Assumed to be shelf-stable • Hermetically sealed container • Often process-safe • Inactivate microorganisms of public health significance • “Retort” thermal processing; commercially sterile • Primary concern: Clostridium botulinum • Must file process with FDA • Including all imported foods

4. Formulation-safe foods • Acid or acidified foods pH < 4.6 • Foods with water activity < 0.85 • Low acid foods with multiple barriers • Combination of pH, aw, antimicrobials • Recommend formulating certain refrigerated foods for safety to control psychrotrophic bacteria ex. Listeria

5. Goal for formulating safe foods • General rule: < 1-log increase of pathogen for time that is 1.5X shelf life as determined by manufacturer • Must be bacteriostatic • Processed meats • No more than 1-log increase of LM during shelf-life • Other shelf-stable foods • No botulinal toxin production 2x shelf-life • Need to consider whole food, individual components, and interfaces of components

6. Risk analysis • Pathogens • Type and level of contamination likely in raw ingredients and environment • Infectious dose • Growth vs. survival • Thermal stability of pathogens • Recontamination potential • Presence of competitive microflora and expected shelf-life

7. Risk analysis • Storage temperature • Shelf-stable vs. refrigerated • “Traditional” vs. novel storage • Modified atmosphere packaging • Temperature control during distribution • Risk of temperature abuse at retail and with consumers • Consider worse case scenario • Reevaluate if formulation changes

8. Do not rely on temperature alone to protect foods • Pasteurization is not perfect • Spore survive pasteurization • Post-pasteurization contamination • Temperature abuse is common • During distribution, at homes, power-outages • Growth of psychrotrophic pathogens • Listeria monocytogenes • Nonproteolytic C. botulinum • Some Bacillus cereus strains

9. Pathogens of concern:“The Big-5” • Clostridium botulinum • Listeria monocytogenes • Staphylococcus aureus • Enterohemorrhagic E. coli • Salmonella

10. Other pathogens of concern • Clostridium perfringens • Bacillus cereus • Campylobacter • Parasites and viruses • Control by: • Same formulation strategies as for “The Big-5” • Good manufacturing and good agricultural practices • Proper heating/cooling • Employee hygiene

11. Foods of concern • Foods that support growth of select pathogens at refrigeration temperatures • Low acid foods with traditional storage at room temperature • High risk foods that can be formulated for enhanced safety • Refrigerated processed meats • Refrigerated foods / entreés with heat treatment • Process cheese products • MAP bakery products • Garlic-in-oil; herbs-in-oil (fresh; not pre-acidified)

12. Factors Affecting Growth

13. Acid and Water Activity • Gram-negative bacteria: acid tolerant • Salmonella, Enterohemorrhagic E. coli survival pH <4.0 • Seldom grow at aw <0.95 • Gram-positive bacteria: salt and aw tolerant • S. aureus • Growth at aw 0.86 • Enterotoxin production ~ 0.91 • L. monocytogenes • Growth at 0.92 • C. botulinum • Growth at 0.93 • Minimal pH for growth 4.5 – 5.2 depending on acidulant

14. Useful Antimicrobials • Phosphate based emulsifiers • C. botulinum in process cheese • Antimycotics (sorbate, benzoate, propionate) • S. aureus, C. botulinum, L. monocytogenes • Organic acid salts (lactate, diacetate) • C. botulinum, L. monocytogenes in meats/other foods • Nitrite (US usage 80-156 ppm) • C. botulinum, L. monocytogenes in meats • Lysozyme (400 ppm in cheese) • Clostridium sp. • Bacteriocins/nisin (250 ppm in cheese) • Bactericidal against gram-positive bacteria

15. Temperature • Acidity • Water activity • Antimicrobials • Competitive microflora • Proper fermentation • Nutrient availability • Oxygen content Hurdle Technology

16. Critical aw values Critical pH values 4.6 or less >4.6– 5.6 >5.6 0.92 or less Non-TCS* Temperature Controlled for Safety Non-TCS Non-TCS >0.92–.95 Non-TCS Non-TCS ? >0.95 Non-TCS ? ? Control of spores Product treated to control vegetative cells and protected from recontamination.

17. Critical aw values Critical pH values <4.2 4.2 – 4.6 >4.6– 5.0 > 5.0 < 0.88 Non-TCS Non-TCS Non-TCS Non-TCS 0.88– 0.90 Non-TCS Non-TCS Non-TCS ? >0.90–.92 Non-TCS Non-TCS ? ? >0.92 Non-TCS ? ? ? Control of vegetative cells and spores Product not treated or treated but not protected from recontamination

18. 7°C 40 ppm NO2 pH 5.3 Aw 0.975 L. monocytogenes USDA-ARS Pathogen Modeling Program 6.0 7°C 40 ppm NO2 pH 5.9 Aw 0.99

19. Examples of Formulation-Safe Foods

20. Formulating Processed Meats • Safety by good manufacturing practices and formulation • Clostridium botulinum • Proteolytic vs. nonproteolytic • Listeria monocytogenes • Staphylococcus aureus • Clostridium perfringens • Enterohemorrhagic E. coli • Salmonella

21. Sodium lactate Sodium diacetate Sodium nitrite Polyphosphates Smoke Drying Fermentation Organic acids Bacteriocins Other antimicrobials Control Strategies for Processed Meats

22. Fermented dried sausage • Reduced pH and aw • Fermentation • Organic acids – primarily lactic acid • Bacteriocins • Competition for nutrients • Nitrites • Effective against LM, C. bot, S.aureus • E. coli O157:H7 reduction usually requires heat

23. E. coli and L. monocytogenes AEM 58:2513 JFP 52:226

24. Refrigerated High-Moisture Processed Meat Formulations L. monocytogenes, 4°C Glass and Doyle, AEM, 1989

25. Effect of temperature and antimicrobials Glass et al, 2002, JFP 65:116

26. Effect of lactate and diacetate Glass et al, 2002, JFP 65:116

27. Formulating Process Cheese(Shelf-Stable) • pH 5.4-6.0 • Aw 0.94-0.96 cheese spread • Aw 0.91-0.93 cheese slices

28. Moisture pH Total salts NaCl Phosphate-based emulsifier Water activity not accurate predictor of safety if 0.93-0.96 Applicable to spreads with >51% cheese; 20-25% fat Controlling C. botulinum in process cheese spreads Tanaka et al, 1986

29. S. aureus, process cheese Glass et al., Unpublished data, 2001 20 formulations – 2 lots each, 27C

30. Formulating Convenience Foods

31. Refrigerated cooked potatoes:Control C. botulinum pH/aw/temp °C Day

32. Chicken-broccoli-sauce entreéControl C. botulinum by pH/lactate

33. MAP Pizza CrustsControl C. botulinum aw/pH/sorbate  supports toxin production Ono toxin production Products contained 0.3% sorbic acid

34. Fresh PastaControl C. botulinum aw/pH Check individual components *supports toxin production ºno toxin production Filled Unfilled

35. What NOT to rely on for safety • Finished product testing for pathogens • Proper handling and refrigeration • Modified atmosphere packaging • Pasteurization or irradiation alone

36. Rely on: • Secondary barriers • GMPs and environmental controls • HACCP • Responsible for 70% decline in listeriosis • Good source of ingredients • Proper and clear labeling • Code dating KEEP REFRIGERATED Use or discard in 7 days after opening Refrigerate after opening Use by…

37. How to start • Predictive modeling • ARS Pathogen Modeling Program 6.0 • www.arserrc.gov/mfs/PATHOGEN.HTM • Purac OptiForm Listeria Control Model • FRI model for process cheese • Published results for specific foods • Verify with challenge testing

38. Formulation Safety Depends on Many Factors • Consider all sources of contamination • Assume pathogens are present in raw ingredients/environment • Use high-quality raw materials with low levels of microorganisms • Reduce/prevent levels of contamination by proper sanitation/heat treatment

39. Formulation Safety…continued • Multiple hurdles • Synergistic interaction means that lower of each factor can be used • Consider effect of competitive microflora • Assure that manufacturing specifications are met • Control storage temperatures wherever possible • Educate consumer with clear code dates and storage conditions on labels

40. For additional information: Kathleen Glass, Ph.D. Assistant Scientist Food Research Institute University of Wisconsin-Madison 1925 Willow Drive Madison, Wisconsin 53593 USA E-mail: kglass@wisc.edu Phone 608.263.6935; Fax: 608.263.1114

41. References • [NACMCF] National Advisory Committee on Microbiological Criteria for Foods. 1998. Hazard analysis and critical control point principles and application guidelines. J Food Prot 61:762-75. • [NSF] NSF International. 2000 Nov. 10. Non-potentially hazardous foods. Ann Arbor (MI): NSF International. Report nr ANSI/NSF 75-2000. 12 p. • IFT Status Summary, Extended Shelf Life Refrigerated Foods: Microbiological Quality and Safety, Vol. 52. Feb. 1998.

42. IFT Task Force, December 31, 2001 • Evaluation and Definition of Potentially Hazardous Foods • Conference for Food Protection website www.foodprotect.org