Potentially Hazardous Food: The Evolving Definition of Temperature Control for Safety

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Potentially Hazardous Food: The Potentially Hazardous Food: The Evolving Definition of Temperature Evolving Definition of Temperature

Control for SafetyControl for SafetyByBy

Don Zink, PhDDon Zink, PhDLead Scientist – Food ProcessingLead Scientist – Food Processing

Office of Plant and Dairy FoodsOffice of Plant and Dairy FoodsCenter for Food Safety and Applied NutritionCenter for Food Safety and Applied Nutrition

U.S. Food and Drug AdministrationU.S. Food and Drug Administration

andandShirley B. Bohm, RS, MPHShirley B. Bohm, RS, MPHConsumer Safety OfficerConsumer Safety Officer

Office of Compliance, DCP, Retail Food ProtectionOffice of Compliance, DCP, Retail Food ProtectionCenter for Food Safety and Applied NutritionCenter for Food Safety and Applied Nutrition

U.S. Food and Drug AdministrationU.S. Food and Drug Administration

NEHA Annual Educational Conference, June 26, 2005

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Food Preservation and Food Preservation and Potentially Hazardous FoodPotentially Hazardous Food

Food safety is constantly evolving:Food safety is constantly evolving:

1825 – U.S. patent granted for preserving food in tin cans1825 – U.S. patent granted for preserving food in tin cans1890 – Commercial pasteurization of milk1890 – Commercial pasteurization of milk1908 – Sodium benzoate approved as a food preservative1908 – Sodium benzoate approved as a food preservative1917 – Frozen foods available at retail1917 – Frozen foods available at retail1962 – “PHF” is defined as perishable food that supports the rapid and 1962 – “PHF” is defined as perishable food that supports the rapid and

progressive growth of infectious or toxigenic microorganismsprogressive growth of infectious or toxigenic microorganisms1976 – Added crustacea and synthetic ingredients to definition, 1976 – Added crustacea and synthetic ingredients to definition,

Exempted foods with pH Exempted foods with pH ≤ 4.6; a≤ 4.6; aww ≤ 0.85; clean, uncracked shell ≤ 0.85; clean, uncracked shell eggs; food in unopened, hermetically sealed containerseggs; food in unopened, hermetically sealed containers

1993 – Added toxin production of 1993 – Added toxin production of C. botulinumC. botulinum; growth of SE in eggs; ; growth of SE in eggs; non-acidified garlic-in-oil; shell eggs; cut melons; raw seed sproutsnon-acidified garlic-in-oil; shell eggs; cut melons; raw seed sprouts

2005 – Added “TCS Food” as an equivalent/transition term for PHF, pH 2005 – Added “TCS Food” as an equivalent/transition term for PHF, pH and aand aw w Interaction Tables, and consideration for pathogenic Interaction Tables, and consideration for pathogenic microorganisms instead of only microorganisms instead of only Clostridium botulinum Clostridium botulinum andand Salmonella Salmonella Enteritidis (1-201.10 in FDA Food Code)Enteritidis (1-201.10 in FDA Food Code)

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Potentially Hazardous FoodPotentially Hazardous Food Why is the definition of “potentially hazardous food” Why is the definition of “potentially hazardous food”

changing in the Food Code?changing in the Food Code?

The “rapid and progressive growth of infectious and The “rapid and progressive growth of infectious and toxigenic microorganisms" in the old definition was not toxigenic microorganisms" in the old definition was not clearly definedclearly defined

The slow growth of low infectious dose pathogens such as The slow growth of low infectious dose pathogens such as Listeria monocytogenesListeria monocytogenes was not considered was not considered

Water activity of 0.85 as a level of safety against Water activity of 0.85 as a level of safety against Staphylococcus aureusStaphylococcus aureus was conservatively low was conservatively low

pH of 4.6 may also be inappropriate as pH of 4.6 may also be inappropriate as Listeria Listeria monocytogenesmonocytogenes grows at 4.39, grows at 4.39, Salmonella Salmonella spp. at 4.2 and spp. at 4.2 and Yersinia enterocoliticaYersinia enterocolitica at 4.2 BUT pH 4.6 is appropriate at 4.2 BUT pH 4.6 is appropriate when only spore forming pathogens are presentwhen only spore forming pathogens are present

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Potentially Hazardous FoodPotentially Hazardous Food Why is the definition of “potentially hazardous food” Why is the definition of “potentially hazardous food”

changing in the Food Code?changing in the Food Code?

Sufficient research has been done on food products to Sufficient research has been done on food products to construct tables that predict the growth of pathogenic construct tables that predict the growth of pathogenic microorganisms when the interaction of both pH and amicroorganisms when the interaction of both pH and aww are are considered (See Tables A & B)considered (See Tables A & B)

Many factors control or prevent the growth and toxin Many factors control or prevent the growth and toxin production of foodborne pathogens besides pH and aproduction of foodborne pathogens besides pH and aww alonealone

There is concern about the use of the word “hazard” which There is concern about the use of the word “hazard” which is used in a different manner in HACCPis used in a different manner in HACCP

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Potentially Hazardous FoodPotentially Hazardous Food Why are some foods considered PHF?Why are some foods considered PHF?

““PHF/TCS food means a food that requires T/T control for safety to PHF/TCS food means a food that requires T/T control for safety to limit pathogenic microorganism growth or toxin formation”limit pathogenic microorganism growth or toxin formation”

• No or inadequate hurdles to pathogenic bacterial growth in the No or inadequate hurdles to pathogenic bacterial growth in the foodfood

Intrinsic factors of the food support the growth of bacterial Intrinsic factors of the food support the growth of bacterial pathogenspathogens

• Nutrients Nutrients Energy source (sugars, alcohols, amino acids)Energy source (sugars, alcohols, amino acids) Nitrogen source (amino acids)Nitrogen source (amino acids) Vitamins and growth factorsVitamins and growth factors Minerals Minerals

• Available water (aAvailable water (aw w ), acidity (pH), redox potential (Eh). etc.), acidity (pH), redox potential (Eh). etc. Epidemiological evidence associates food with foodborne Epidemiological evidence associates food with foodborne

outbreaksoutbreaks

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Sliced/Diced TomatoesSliced/Diced Tomatoes Not heat-treated to destroy spore Not heat-treated to destroy spore

formersformers Not treated with any other anti-Not treated with any other anti-

microbial processmicrobial process pH is pH is < 4.6< 4.6 aaw w is > 0.99is > 0.99 Considered PHF unless a product Considered PHF unless a product

assessment proves otherwiseassessment proves otherwise

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Cut MelonCut Melon Not heat-treated to destroy spore formersNot heat-treated to destroy spore formers Not treated with any other antimicrobial Not treated with any other antimicrobial

processprocess pH of melons;pH of melons;

Honeydew pH = 6.3 – 6.7Honeydew pH = 6.3 – 6.7 Watermelon pH = 5.2 – 5.6Watermelon pH = 5.2 – 5.6 Cantaloupe pH = 6.2 – 7.1Cantaloupe pH = 6.2 – 7.1

aaw w is > 0.99is > 0.99 Considered a PHF unless a product Considered a PHF unless a product


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Dye Infiltration in CantaloupeDye Infiltration in Cantaloupe

Photo courtesy of Dr. Michelle Smith, FDA/CFSAN

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Dye Infiltration in CantaloupeDye Infiltration in Cantaloupe

Photo courtesy of Dr. Michelle Smith, FDA/CFSAN

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Dye buildup on canker(rind blemish)

Photos courtesy of Dr. Michelle Smith, FDA/CFSAN

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Raw Seed SproutsRaw Seed Sprouts Not heat-treated to destroy spore Not heat-treated to destroy spore

formersformers Not treated with any other antimicrobial Not treated with any other antimicrobial

processprocess pH is pH is > 6.5> 6.5 aaw w is > 0.99is > 0.99 Considered a PHF, unless a product Considered a PHF, unless a product


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Potentially Hazardous FoodPotentially Hazardous Food Why are some foods considered non-PHF?Why are some foods considered non-PHF?

If the food’s pH If the food’s pH ≤ 4.6, it is below the pH at which proteolytic ≤ 4.6, it is below the pH at which proteolytic Clostridium botulinumClostridium botulinum can grow and produce toxin: can grow and produce toxin:

• Because of inherent acidity – fruitsBecause of inherent acidity – fruits• Because of acid from bacterial activity – fermented Because of acid from bacterial activity – fermented

sausages, fermented milks, sauerkrauts, picklessausages, fermented milks, sauerkrauts, pickles• Because of acidification – added vinegarBecause of acidification – added vinegar

If the food’s aIf the food’s aw w ≤ 0.85, it is below the water activity at which ≤ 0.85, it is below the water activity at which Staphylococcus aureus Staphylococcus aureus grows and produces toxin:grows and produces toxin:

• Not enough water is available for metabolic activities of Not enough water is available for metabolic activities of pathogenic bacteriapathogenic bacteria

• Low aLow aww increases the length of the bacterial lag phase and increases the length of the bacterial lag phase and decreases the growth ratedecreases the growth rate

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PotentiallyPotentially Hazardous FoodHazardous Food Which foods are considered non-PHF?Which foods are considered non-PHF?

Unopened containers of hermetically sealed Unopened containers of hermetically sealed containers are “commercially sterile”containers are “commercially sterile”

Foods with laboratory evidence showing that T/T Foods with laboratory evidence showing that T/T control is not required AND the food contains:control is not required AND the food contains:

• A preservative to inhibit pathogens – see 21 CFR 172 A preservative to inhibit pathogens – see 21 CFR 172 Subpart B, Food PreservativesSubpart B, Food Preservatives

• Other barriers/hurdles to pathogenic growthOther barriers/hurdles to pathogenic growth• A combination of barriers/hurdles to inhibit pathogenic A combination of barriers/hurdles to inhibit pathogenic

growthgrowth

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Examples of Examples of Non-PHF/Non-TCS FoodNon-PHF/Non-TCS Food

Air-cooled, hard boiled egg – shell intactAir-cooled, hard boiled egg – shell intact Shell eggs treated to destroy all SE – Shell eggs treated to destroy all SE –

pasteurized shell eggspasteurized shell eggs A food that does not support the A food that does not support the growth growth of of

pathogenic microorganisms even though pathogenic microorganisms even though they may be present (i.e., they may be present (i.e., E.coli E.coli O157:H7 O157:H7 in apple cider or norovirus on crackers)in apple cider or norovirus on crackers)

Some foods that are refrigerated for Some foods that are refrigerated for quality, not safetyquality, not safety

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Interaction TablesInteraction Tables The The “hurdle” effect“hurdle” effect is used – several inhibitory factors used is used – several inhibitory factors used

together to control or eliminate pathogens that would together to control or eliminate pathogens that would otherwise be ineffective when used alone otherwise be ineffective when used alone

The effect of a The effect of a heat treatmentheat treatment which destroys vegetative cells which destroys vegetative cells is consideredis considered

The effect of The effect of packagingpackaging which prevents re-contamination is which prevents re-contamination is consideredconsidered

When tables indicateWhen tables indicate “Product Assessment Required” (PA), “Product Assessment Required” (PA), the the food must be treated as PHF/TCS Foodfood must be treated as PHF/TCS Food until laboratory until laboratory evidence shows otherwiseevidence shows otherwise

Tables A & B consider the interaction of pH and aTables A & B consider the interaction of pH and aw w under under certain conditions of heat-treatment and packagingcertain conditions of heat-treatment and packaging

Refer to “Factors Affecting the Growth of Some Foodborne Pathogens” in FDA’s Refer to “Factors Affecting the Growth of Some Foodborne Pathogens” in FDA’s Foodborne Pathogenic Microorganisms and Natural Toxins Handbook (Bad Bug Foodborne Pathogenic Microorganisms and Natural Toxins Handbook (Bad Bug Book) at Book) at http://www.cfsan.fda.gov/~mow/factors.htmlhttp://www.cfsan.fda.gov/~mow/factors.html

http://www.cfsan.fda.gov/~mow/factors.html

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Water Activity in FoodsWater Activity in Foods Water activity (aWater activity (aw w ) is the water in foods that is ) is the water in foods that is

available for metabolic purposesavailable for metabolic purposes aaw w = p / p= p / po o (pure water is 1.00)(pure water is 1.00)

Effect of aEffect of aw w on microorganismson microorganisms Most spoilage organisms do not grow below 0.91Most spoilage organisms do not grow below 0.91 Spoilage molds can grow as low as 0.80Spoilage molds can grow as low as 0.80 Staphylococcus aureus Staphylococcus aureus can grow as low as 0.86can grow as low as 0.86 Clostridium botulinumClostridium botulinum can grow & produce toxin as low as can grow & produce toxin as low as

0.940.94 Some parasites (Some parasites (Trichinella spiralis)Trichinella spiralis) survive at low a survive at low aw w

Water activity ranges for growth are affected by Water activity ranges for growth are affected by temperature and nutrient levelstemperature and nutrient levels

Water activity in a food can be changed by adding salt Water activity in a food can be changed by adding salt or sugar or by dryingor sugar or by drying

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Acidity in FoodsAcidity in Foods pH is a measure of acidity in food using a scale of 0 to 14, with pH is a measure of acidity in food using a scale of 0 to 14, with

7.0 being neutral7.0 being neutral Microorganisms grow best in neutral or slightly acidic Microorganisms grow best in neutral or slightly acidic

conditionsconditions Yeasts and molds can grow at pH Yeasts and molds can grow at pH ≤ 3.5≤ 3.5 Clostridium botulinum Clostridium botulinum can grow and produce toxin as low can grow and produce toxin as low

as pH 4.7as pH 4.7 Staphylococcus aureus Staphylococcus aureus can grow at pH 4.2can grow at pH 4.2 Listeria monocytogenes Listeria monocytogenes and and Yersinia enterocoliticaYersinia enterocolitica can can

grow down to pH 4.4grow down to pH 4.4 The minimum pH for growth of microorganisms is dependent The minimum pH for growth of microorganisms is dependent

on many factors – inherent acidity, type of acid, salt on many factors – inherent acidity, type of acid, salt concentrationconcentration

The further out (above or below) the optimum pH for growth, The further out (above or below) the optimum pH for growth, the longer the lag phase will bethe longer the lag phase will be

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Other Factors AffectOther Factors AffectMicrobial GrowthMicrobial Growth

Other factors affect the growth of pathogenic Other factors affect the growth of pathogenic microorganisms besides pH and amicroorganisms besides pH and aw w

Redox potential (ease of transferring electrons in food Redox potential (ease of transferring electrons in food during energy metabolism)during energy metabolism)

Atmosphere within packaging (i.e., ROP)Atmosphere within packaging (i.e., ROP) Antimicrobials and bacteriosins (i.e., nisin)Antimicrobials and bacteriosins (i.e., nisin)

If other factors besides pH and aIf other factors besides pH and aw w are used to show are used to show that the food is non-PHF, a pathogen modeling that the food is non-PHF, a pathogen modeling program* or laboratory evidence must be providedprogram* or laboratory evidence must be provided

*USDA’s Pathogen Modeling Program can be downloaded at *USDA’s Pathogen Modeling Program can be downloaded at http://www.ars.usda.gov/Services/docs.htm?docid=6784http://www.ars.usda.gov/Services/docs.htm?docid=6784

http://www.ars.usda.gov/Services/docs.htm?docid=6784

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Interaction Table AInteraction Table ATable A. Interaction of pH and aTable A. Interaction of pH and aww for control of spores in food heat- for control of spores in food heat-treated to destroy vegetative cells and subsequently packaged.treated to destroy vegetative cells and subsequently packaged.

aaww Values Values pH ValuespH Values4.6 or less4.6 or less > 4.6 – 5.6> 4.6 – 5.6 > 5.6> 5.6

0.92 or less0.92 or less Non-PHF*/non-Non-PHF*/non-TCS**TCS**

Non-PHF/non-Non-PHF/non-TCSTCS


> 0.92 – 0.95> 0.92 – 0.95 Non-PHF/non-Non-PHF/non-TCSTCS


PA***PA***

> 0.95> 0.95 Non-PHF/non-Non-PHF/non-TCSTCS

PAPA PAPA

* PHF means “Potentially Hazardous Food”* PHF means “Potentially Hazardous Food”** TCS means “Time/Temperature Control for Safety Food”** TCS means “Time/Temperature Control for Safety Food”*** PA means “Product Assessment Required”*** PA means “Product Assessment Required”

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When to Use Interaction Table AWhen to Use Interaction Table A Table A can be used to determine if a food Table A can be used to determine if a food

which is heat-treated and packaged is PHF, which is heat-treated and packaged is PHF, Non-PHF or Requires Product AssessmentNon-PHF or Requires Product Assessment Food must meet cooking requirements of Food Food must meet cooking requirements of Food

Code section 3-401.11 (no partial cooks) to Code section 3-401.11 (no partial cooks) to eliminate vegetative pathogenseliminate vegetative pathogens

Spore forming pathogens are the only remaining Spore forming pathogens are the only remaining biological hazards of concernbiological hazards of concern

Food is packaged to prevent re-contaminationFood is packaged to prevent re-contamination Therefore, higher pH & aTherefore, higher pH & aww can be safely tolerated can be safely tolerated

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Interaction Table BInteraction Table BTable B. Interaction of pH and aTable B. Interaction of pH and aww for control of vegetative cells and spores for control of vegetative cells and spores in food not heat-treated or heat-treated but not packaged.in food not heat-treated or heat-treated but not packaged.

aaww Values Values pH ValuespH Values

< 4.2< 4.2 4.2 – 4.64.2 – 4.6 > 4.6 – 5.0> 4.6 – 5.0 > 5.0> 5.0

< 0.88< 0.88 Non-PHF*/non-Non-PHF*/non-TCS**TCS**


Non-PHD/non-Non-PHD/non-TCSTCS


0.88 – 0.900.88 – 0.90 Non-PHF/non-Non-PHF/non-TCSTCS



PA***PA***

> 0.90 – 0.92> 0.90 – 0.92 Non-PHF/non-Non-PHF/non-TCSTCS


PAPA PAPA

> 0.92> 0.92 Non-PHF/non-Non-PHF/non-TCSTCS

PAPA PAPA PAPA

* PHF means “Potentially Hazardous Food”* PHF means “Potentially Hazardous Food”** TCS means “Time/Temperature Control for Safety Food”** TCS means “Time/Temperature Control for Safety Food”*** PA means “Product Assessment Required”*** PA means “Product Assessment Required”

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When to Use Interaction Table BWhen to Use Interaction Table B Table B can be used to determine if a food Table B can be used to determine if a food

which is not heat-treated or heat-treated but which is not heat-treated or heat-treated but not packaged is PHF, Non-PHF or Requires not packaged is PHF, Non-PHF or Requires Product AssessmentProduct Assessment Food not heat-treated may contain vegetative Food not heat-treated may contain vegetative

cells and pathogenic sporescells and pathogenic spores Food that was heat-treated but not packaged may Food that was heat-treated but not packaged may

become re-contaminatedbecome re-contaminated pH values considered in Table B must include 4.2 pH values considered in Table B must include 4.2

because because Staphylococcus aureusStaphylococcus aureus can grow at that can grow at that levellevel

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Use of aUse of aww/pH Interaction /pH Interaction Tables Decision TreeTables Decision Tree

Is the food heat-treated?

No Yes

Is the food treated using some other method?

Is it packaged to preventRecontamination?

Yes No Yes No

Further product assessment(PA) or vendor

documentation required

Using the food’s known pH &/oraw values, position the food in

the correct table

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Use of aUse of aww/pH Interaction /pH Interaction Tables Decision TreeTables Decision Tree

Using the food’s known pH and/or aw, position the food in the

appropriate table

Use Table A(heat-treated and

packaged)

Use Table B(not heat-treated or heat-treated but not packaged)

Non-PHF/non-TCSFood may be heldout of temperature

control and is consideredshelf stable

Product AssessmentFurther product

assessment or vendor documentation

required

Non-PHF/non-TCSFood may be heldout of temperature

control and isconsidered safe

from bacterial pathogens

Product AssessmentFurther product

Assessment or vendorDocumentation

required

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Application of Interaction Application of Interaction TablesTables

Preliminary questions:Preliminary questions: Is the food held refrigerated for quality, not safety – NOT Is the food held refrigerated for quality, not safety – NOT

enforceable – What is the scientific basis?enforceable – What is the scientific basis? Consider the food’s safety history – if not associated with Consider the food’s safety history – if not associated with

foodborne outbreaks, scientific rationale should be able to foodborne outbreaks, scientific rationale should be able to explainexplain

Any pH and aAny pH and aw w values must be accurate and replicable from a values must be accurate and replicable from a competent laboratorycompetent laboratory

• pH value – chemistry grade pH paper accurate to pH value – chemistry grade pH paper accurate to ±0.05 or ±0.05 or calibrated equipmentcalibrated equipment

• aaw w value – homogenous sample with calibrated equipmentvalue – homogenous sample with calibrated equipment Heat-treatment must destroy vegetative cellsHeat-treatment must destroy vegetative cells Packaging must be sufficient to prevent recontaminationPackaging must be sufficient to prevent recontamination Product assessment may result in a finding of non-PHF, Product assessment may result in a finding of non-PHF,

limited shelf life or Time as a Public Health Control, required limited shelf life or Time as a Public Health Control, required temperature control or reformulation of producttemperature control or reformulation of product

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Application of Interaction Application of Interaction Tables - Parmesan CheeseTables - Parmesan Cheese

Parmesan Cheese: Parmesan Cheese: aaw w = 0.68 – 0.76 = 0.68 – 0.76 pH = 6.5 pH = 6.5 curd heated to ~ 130curd heated to ~ 130°°F & cured 2-3 years, then packagedF & cured 2-3 years, then packaged

Ambient storage desired & no history of related Ambient storage desired & no history of related illnessillness

The food is heat-treated/cured & packagedThe food is heat-treated/cured & packaged Using this information, Table A is chosenUsing this information, Table A is chosen Locate the cheese’s aLocate the cheese’s aw w (0.68 – 0.76) in the correct line (0.68 – 0.76) in the correct line

and pH (6.5) in the correct columnand pH (6.5) in the correct column They intersect at “Non-PHF/Non-TCS”They intersect at “Non-PHF/Non-TCS”

No temperature control is requiredNo temperature control is required

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Application of Interaction TablesApplication of Interaction TablesAmerican Process Cheese SlicesAmerican Process Cheese Slices American Process Cheese SlicesAmerican Process Cheese Slices

aaw w = 0.94 – 0.95= 0.94 – 0.95 pH = 5.5 – 5.8pH = 5.5 – 5.8 Heat processing and packaged to retailHeat processing and packaged to retail

Ambient storage desired for 24 hrs.Ambient storage desired for 24 hrs. Cheese is heat-treated and unpackagedCheese is heat-treated and unpackaged Table B is chosen because it may become recontaminatedTable B is chosen because it may become recontaminated Locate the cheese’s aLocate the cheese’s aw w (0.94 – 0.95) in the correct line and pH (0.94 – 0.95) in the correct line and pH

(5.5 – 5.8) in the correct column(5.5 – 5.8) in the correct column They intersect at PA – Product Assessment RequiredThey intersect at PA – Product Assessment Required

Challenge testing with 4 pathogens at 86Challenge testing with 4 pathogens at 86°F showed no growth °F showed no growth for 24 hrs. and no growth for 210 days when refrigeratedfor 24 hrs. and no growth for 210 days when refrigerated

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Application of Interaction TablesApplication of Interaction TablesSushi Roll with Raw FishSushi Roll with Raw Fish

Sushi roll with raw fish:Sushi roll with raw fish: Cooked rice:Cooked rice:

• aaw w = 0.98 – 0.99= 0.98 – 0.99• pH = 6.0 – 6.7 (acidified rice pH = 4.2)pH = 6.0 – 6.7 (acidified rice pH = 4.2)

Raw fish:Raw fish:• aaw w = = > 0.99> 0.99• pH = 5.2 – 6.1 (tuna), 6.1 -6.3 (salmon), 6.8 – 7.0 (shrimp)pH = 5.2 – 6.1 (tuna), 6.1 -6.3 (salmon), 6.8 – 7.0 (shrimp)

Ambient temperature display desired for buffet lineAmbient temperature display desired for buffet line Only rice, not fish is heat-treated & not packagedOnly rice, not fish is heat-treated & not packaged Locate the food’s aLocate the food’s aw w and pH in the correct line and columnand pH in the correct line and column They intersect at PA – product assessment requiredThey intersect at PA – product assessment required

• The food is PHF unless reformulated in some wayThe food is PHF unless reformulated in some way• If room temperature display (for 4 hrs.) is desired, TPHC can be used if If room temperature display (for 4 hrs.) is desired, TPHC can be used if

a marking system is used and any left after 4 hrs. is discardeda marking system is used and any left after 4 hrs. is discarded• If the sushi roll with raw fish was packaged for retail sale, Table B is If the sushi roll with raw fish was packaged for retail sale, Table B is

still used because of the raw fishstill used because of the raw fish

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Evaluation of Laboratory Evaluation of Laboratory EvidenceEvidence

When is laboratory evidence likely to be When is laboratory evidence likely to be used?used? Variance applicationVariance application Performance standardPerformance standard Preservatives addedPreservatives added New technologies usedNew technologies used pH and apH and aw w Interaction Tables say “PA” – Product Interaction Tables say “PA” – Product

Assessment RequiredAssessment Required Multi-ingredient or combination foods with two or Multi-ingredient or combination foods with two or

more distinct food components - the more distinct food components - the interface interface may have different propertiesmay have different properties than either of the than either of the individual ingredientsindividual ingredients

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Microbiological challenge testingMicrobiological challenge testing Design, implementation and assessment Design, implementation and assessment

must be done by an must be done by an EXPERT EXPERT MICROBIOLOGISTMICROBIOLOGIST

Failure to account for a specific product or Failure to account for a specific product or environmental factors in the design could environmental factors in the design could result in a result in a flawed conclusionflawed conclusion

A A competent laboratorycompetent laboratory should be used to should be used to conduct the challenge testingconduct the challenge testing

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What factors should be considered in designing What factors should be considered in designing a challenge study?*a challenge study?*

Selection of challenge organism(s)Selection of challenge organism(s) Level of challenge inoculumsLevel of challenge inoculums Inoculums preparation and methodologyInoculums preparation and methodology Duration of the studyDuration of the study Formulation factors and storage conditionsFormulation factors and storage conditions Sample analysisSample analysis

*For more information, refer to Ch. 6 in “Evaluation and Definition of *For more information, refer to Ch. 6 in “Evaluation and Definition of Potentially Hazardous Food” at Potentially Hazardous Food” at http://www.cfsan.fda.gov/~comm/ift4-toc.htmlhttp://www.cfsan.fda.gov/~comm/ift4-toc.html

http://www.cfsan.fda.gov/~comm/ift4-toc.html

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Potentially Hazardous Food: The Evolving Definition of Temperature Control for Safety