Formulating foods for microbiological safety
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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.

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Formulating Foods for Microbiological Safety

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Formulating foods for microbiological safety

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

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)


Factors affecting growth

Factors Affecting Growth


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


Formulating foods for microbiological safety

  • Temperature

  • Acidity

  • Water activity

  • Antimicrobials

  • Competitive microflora

  • Proper fermentation

  • Nutrient availability

  • Oxygen content

Hurdle Technology


Formulating foods for microbiological safety

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.


Formulating foods for microbiological safety

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


Formulating foods for microbiological safety

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


Examples of formulation safe foods

Examples of Formulation-Safe Foods


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

Polyphosphates

Smoke

Drying

Fermentation

Organic acids

Bacteriocins

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

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


S aureus process cheese

S. aureus, process cheese

Glass et al., Unpublished data, 2001

20 formulations – 2 lots each, 27C


Formulating convenience foods

Formulating Convenience Foods


Refrigerated cooked potatoes control c botulinum ph a w temp

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

°C

Day


Chicken broccoli sauce entre control c botulinum by ph lactate

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


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

components

*supports toxin production

ºno toxin production

Filled

Unfilled


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

  • 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…


How to start

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


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


References

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.


Formulating foods for microbiological safety

  • IFT Task Force, December 31, 2001

    • Evaluation and Definition of Potentially Hazardous Foods

    • Conference for Food Protection website www.foodprotect.org


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