Formulating Foods for Microbiological Safety by 46CZmY

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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
 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
   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 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
   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
 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 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
 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”
 Clostridium botulinum
 Listeria monocytogenes
 Staphylococcus aureus
 Enterohemorrhagic E. coli
 Salmonella
    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 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
            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
   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
                   Temperature
                   Acidity
                   Water activity
                   Antimicrobials
                   Competitive
                    microflora
                   Proper fermentation
                   Nutrient availability
                   Oxygen content


Hurdle Technology
               Control of spores
 Product treated to control vegetative cells and
      protected from recontamination.
Critical aw                     Critical pH values
 values
               4.6 or less           >4.6– 5.6        >5.6

0.92 or less   Non-TCS*             Non-TCS          Non-TCS
               Temperature
               Controlled for
                  Safety
 >0.92–.95     Non-TCS              Non-TCS             ?



   >0.95       Non-TCS                  ?               ?
       Control of vegetative cells and spores
           Product not treated or treated
      but not protected from recontamination
 Critical              Critical pH values
aw 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      ?           ?           ?
USDA-ARS Pathogen Modeling Program 6.0   L. monocytogenes
                                         7°C
                                         40 ppm NO2
                                         pH 5.9
                                         Aw 0.99




     7°C
     40 ppm NO2
     pH 5.3
     Aw 0.975
     Examples of
Formulation-Safe Foods
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        Drying
   Sodium diacetate      Fermentation
   Sodium nitrite        Organic acids
   Polyphosphates        Bacteriocins
   Smoke                 Other
                           antimicrobials
     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




AEM 58:2513
JFP 52:226
                  Refrigerated High-Moisture
                 Processed Meat Formulations
            8   L. monocytogenes, 4°C
            7

            6
                                                                 Ham
            5                                                    Turkey
log cfu/g




            4                                                    Wieners
            3                                                    Beef
            2                                                    Salami
            1

            0
                  0         2           4    6
                                Week

                                            Glass and Doyle, AEM, 1989
                      Effect of
            temperature and antimicrobials
                    L. monocytogenes on cooked sausage;
            6            3.4% lactate / 0.1% diacetate

            5

            4
log cfu/g




                                                           unsmoked,3C
            3                                              smoked,3C
                                                           unsmoked,7C
            2
                                                           smoked,7C
            1

            0
                0      2   Week 4       8       12

                                               Glass et al, 2002, JFP 65:116
                   Effect of lactate and diacetate
                        LM, lactate/diacetate, wieners, 4C

              11
                                                                              1.32% L
              10                                                              2.0% L
               9                                                              2.5% L
Log cfu/pkg




               8                                                              3.0% L
               7                                                              3.5% L
               6                                                              1%L/.1% D
               5                                                              1%L/.25% D

               4                                                              2%L/.1% D
                    0      7        14         30     45        60
                                         Day



                                                             Glass et al, 2002, JFP 65:116
    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
                Tanaka et al, 1986
S. aureus, process cheese
            10
                     Growth of S. aureus at pH >5.6; no sorbic acid
            9

            8

            7
log CFU/g




            6

            5

            4

            3

            2

            1

            0
                 0        0.5        1        1.5          2      3       4        7
                                                    days

Glass et al., Unpublished data, 2001                 20 formulations – 2 lots each, 27C
Formulating Convenience Foods
Refrigerated cooked potatoes:
Control C. botulinum pH/aw/temp

            pH 5.75, aw .995        pH 5.8, aw .985
°C
     Day    4     12.8     27      4     12.8     27
  4         --     --      3/3     --      --     0/3
  7         --     --      3/3     --      --     2/3
  14       0/3    0/3     Disc.   0/3     0/3     2/3
  30       0/3    0/3     Disc.   0/3     0/3    Disc.
  45       0/3    1/3     Disc.   0/3     0/3    Disc.
  60       0/3    1/3     Disc.   0/3     0/3    Disc.
 103       0/3   Disc. Disc.      0/3    Disc. Disc.
Chicken-broccoli-sauce entreé
Control C. botulinum by pH/lactate
 Effect of sodium lactate and pH    Days to toxicity

    #       pH     % H 2O    NaL     12.8°    27°C
    1       6.3      80        --      7        7
    2       6.4      80       2.0      7        7
    3       5.5      84        --     35        7
    4       5.1      80        --     35        7
    5       5.1      80       2.0    >105     >105
    6       4.8      82        --    >105      35
MAP Pizza Crusts
Control C. botulinum
aw/pH/sorbate
                  supports toxin production
      0.96       O no toxin production
      0.95

      0.94
 Aw




      0.93
      0.92

      0.91
       0.9
             5            5.2        5.4        5.6   5.8   6
Products contained 0.3% sorbic acid        pH
Fresh Pasta
Control C. botulinum aw/pH
     0.99         * supports toxin                         Check individual
                  production
     0.98                                                  components
                  º no toxin production
     0.97
                                            Filled             Unfilled
     0.96
Aw




     0.95
     0.94
     0.93
     0.92
     0.91
            5.5        5.7      5.9       6.1        6.3      6.5     6.7   6.9
                                                pH
    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:
 Secondary barriers
 GMPs and environmental controls
 HACCP
     Responsible for 70% decline in listeriosis
 Good source of ingredients
 Proper and clear labeling
     Code dating


                               Use by…
                 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
   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
   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:

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
              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.
   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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