formulating foods for microbiological safety
Skip this Video
Download Presentation
Formulating Foods for Microbiological Safety

Loading in 2 Seconds...

play fullscreen
1 / 42

Formulating Foods for Microbiological Safety - PowerPoint PPT Presentation

  • Uploaded on

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. Formulation-safe foods.

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
Download Presentation

PowerPoint Slideshow about ' Formulating Foods for Microbiological Safety' - james-conner

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
formulating foods for microbiological safety

Formulating Foods for Microbiological Safety

Kathleen Glass, Ph.D.

Assistant Scientist

Food Research Institute

University of Wisconsin-Madison


International Association for Food Protection

BAFP 21 November 2003

Florianópolis Brasil

formulation safe foods
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”
low acid foods
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
formulation safe foods1
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
goal for formulating safe foods
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
risk analysis
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
risk analysis1
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
do not rely on temperature alone to protect foods
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
pathogens of concern the big 5
Pathogens of concern:“The Big-5”
  • Clostridium botulinum
  • Listeria monocytogenes
  • Staphylococcus aureus
  • Enterohemorrhagic E. coli
  • Salmonella
other pathogens of concern
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
foods of concern
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)
acid and water activity
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
useful antimicrobials
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


  • Acidity
  • Water activity
  • Antimicrobials
  • Competitive microflora
  • Proper fermentation
  • Nutrient availability
  • Oxygen content

Hurdle Technology


Critical aw values

Critical pH values

4.6 or less

>4.6– 5.6


0.92 or less


Temperature Controlled for Safety











Control of spores

Product treated to control vegetative cells and protected from recontamination.


Critical aw values

Critical pH values


4.2 – 4.6

>4.6– 5.0

> 5.0

< 0.88





0.88– 0.90















Control of vegetative cells and spores

Product not treated or treated

but not protected from recontamination



40 ppm NO2

pH 5.3

Aw 0.975

L. monocytogenes

USDA-ARS Pathogen Modeling Program 6.0


40 ppm NO2

pH 5.9

Aw 0.99

formulating processed meats
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
control strategies for processed meats
Sodium lactate

Sodium diacetate

Sodium nitrite





Organic acids


Other antimicrobials

Control Strategies for Processed Meats
fermented dried sausage
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
e coli and l monocytogenes
E. coli and L. monocytogenes

AEM 58:2513

JFP 52:226

refrigerated high moisture processed meat formulations
Refrigerated High-Moisture Processed Meat Formulations

L. monocytogenes, 4°C

Glass and Doyle, AEM, 1989

effect of temperature and antimicrobials
Effect of temperature and antimicrobials

Glass et al, 2002, JFP 65:116

effect of lactate and diacetate
Effect of lactate and diacetate

Glass et al, 2002, JFP 65:116

formulating process cheese shelf stable
Formulating Process Cheese(Shelf-Stable)
  • pH 5.4-6.0
  • Aw 0.94-0.96 cheese spread
  • Aw 0.91-0.93 cheese slices
controlling c botulinum in process cheese spreads


Total salts


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

s aureus process cheese
S. aureus, process cheese

Glass et al., Unpublished data, 2001

20 formulations – 2 lots each, 27C

map pizza crusts control c botulinum a w ph sorbate
MAP Pizza CrustsControl C. botulinum aw/pH/sorbate

 supports toxin production

Ono toxin production

Products contained 0.3% sorbic acid

fresh pasta control c botulinum a w ph
Fresh PastaControl C. botulinum aw/pH

Check individual


*supports toxin production

ºno toxin production



what not to rely on for safety
What NOT to rely on for safety
  • Finished product testing for pathogens
  • Proper handling and refrigeration
  • Modified atmosphere packaging
  • Pasteurization or irradiation alone
rely on
Rely on:
  • Secondary barriers
  • GMPs and environmental controls
    • Responsible for 70% decline in listeriosis
  • Good source of ingredients
  • Proper and clear labeling
    • Code dating


Use or discard in 7 days after opening

Refrigerate after opening

Use by…

how to start
How to start
  • Predictive modeling
    • ARS Pathogen Modeling Program 6.0
    • Purac OptiForm Listeria Control Model
    • FRI model for process cheese
  • Published results for specific foods
  • Verify with challenge testing
formulation safety depends on many factors
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
formulation safety continued
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
for additional information

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: [email protected]

Phone 608.263.6935; Fax: 608.263.1114

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