Appendix I - Hurdles

Microbial growth is dependent upon many environmental conditions such as: ingredients, nutrients, water activity, pH, presence of preservatives (e.g., curing salts), competitive microbiological flora, gas atmosphere, redox potential, storage tempertature and time. Control of these condition can therefore be used to limit microbial growth.

For refrigerated foods, an important saftety hurdle to control microbial growth is refrigeration. A wide variety of refrigerated foods also make use of additional factors to control microbial growth called hurdles.

To extend the shelf life of refrigerated packaged foods, generally more than one barrier is used to control microbial growth, to inhibit spoilage and to prevent foodborne disease. Suitable combinations of hurdles can be devised so that the organisms of concern can no longer grow/survive in the product. The presence of a number of hurdles inhibiting or eliminating microorganisms may be synergistic. Therefore it may require less of each barrier to control growth than would be expected from considering the effect of each individual barrier.

When using the barrier concept for product development, the effect of the barrier(s) on product shelf life and safety should be considered thoroughly. For example, a certain type of modified atmosphere might inhibit the growth of spoilage organisms in refrigerated food. The growth of these microorganisms, which could inhibit toxin production or act as an indicator of poor storage conditions, is limited. Therefore the extension of the product's shelf life may lead to the growth of pathogenic microorganisms without any signs of spoilage.

Examples of hurdles, other than refrigeration, are:

a) Water activity

Microorganisms vary in their ability to grow at reduced levels of a_w and will be inhibited as the available water is reduced. A reduction of water activity to 0.94 is, to varying degrees, usually adequate to suppress the growth of most pathogenic bacteria, particularly at low temperatures. Yeast and mold are the only organisms that can grow below a water activity below 0.85. Note that vegetative cells may show increased heat resistance at lower water activities.

(b) pH

It is well known that decreasing pH is an effective way of controlling the growth of microorganisms. For example, pasteurized products with pH less than 4.5 are bacteriologically stable, because most vegetative microorganisms are inactivated by a mild heat treatment and surviving bacilli and clostridia are inhibited by the low pH. However, for meat and vegetable products, a small reduction of pH from their normal range (6.0–6.5) to about 5.0–5.2 will have a beneficial effect in the context of combined hurdles.

(c) Inoculation with competitive microbiological flora

It is recognized that many foodborne pathogens are poor competitors. Therefore, inoculation with harmless/non pathogenic competitive microbiological flora such as lactic acid bacteria may reduce the pH and may inhibit growth of pathogens. The effect of such inoculation should be proven to be effective against the target organism(s).

For instance, if a refrigerated food is to be packed in a reduced oxygen atmosphere and has a shelf life longer than 10 days, one or more of the following hurdles should also be considered as a way to control psychrotrophic strains of Clostridium botulinum (non proteolytic) in combination with a heat process, if this heat process is not equivalent to 90°C for 10 minutes:

• adjust water activity (a_w) to below 0.97;

• increase acidity by lowering pH below 5.0;

• add sodium chloride to 3% in brine;

• use combinations of water activity, pH, modified atmosphere, storage temperature etc. that demonstrably will inhibit the growth of psychrotrophic strains of Clostridium botulinum within the shelf life and expected storage conditions.

Predictive models may be used to estimate both the effectiveness of preservation conditions and the effects of modifying product composition and varying handling/storage conditions on safety.

Whenever there is doubt that the conditions applied might not effectively control the microorganisms of concern (including estimation resulting from predictive modelling), challenge studies should be conducted. Such studies, in which specific organisms are inoculated into products prior to storage, should use the worst case conditions of expected storage and distribution. It is advisable that scientific advice is sought.

Useful References

“Retail Guidelines: Refrigerated Foods in Reduced Oxygen Packages'”, Us Association of Food & Drug Officials.

“Interaction of Factors to Control Microbial Spoilage of Refrigerated Foods”', VN Scott, J. Food Prot., 1989, 52(6), 431–5.

“Guidelines for the Development, Production, Distribution and Handling of Refrigerated Foods” 1989, US National Food Processors Association.

“Mechanism of Action of Food Preservation Procedures”, 1989, GW Gould (Editor) Elsevier Applied Science London.

“Food Preservatives and the Microbiological Consequences of their Reduction or Omission”. TA Roberts, PJ McClure, Proc. Nutr. Soc., 1990, 49(1), 1–12.

“Guidelines for Microbiological Challenge Testing” 1987. CFDRA. Technical Manual No. 20.

APPENDIX II: Examples

This appendix includes three examples of refrigerated packaged foods. Each of these examples present different:

• process technologies;

• barrier(s) used;

• specific shelf lives;

• risks.

These examples will illustrate the use of the HACCP approach. Under no circumstances should they be used as such for the implementation of a HACCP program in a specific facility.

1) BEEF BOURGUIGNON

1.1 Product Definition

Incoming materials as received:

• frozen beef

• bacon

• sliced raw carrot

• sliced frozen mushrooms

• dried broth

• sterilized spices

• concentrated red wine

• trays and plastic film

Important processing characteristics:

• preparation of ingredients before use

• packaged hermetically

• heat treatment after packaging

1.2 Intended use

• shelf life: 42 days

• ready-to-eat, reheating prior to consumption

• to be kept under refrigeration at 4°C or less

1.3 Process flow diagram

1.4 Hazard Identification

For this beef bourguignon, the foodborne pathogen of concern is Clostridium botulinum. Other pathogens of concern (e.g. Listeria, Salmonella) can be controlled by the heat treatment.

1.5 Identification of Preventative Measures

Control of Clostridium botulinum can be accomplished by:

• heat treatment (minimum of 90°C for 10 min, internal temperature, or equivalent).

• other pathogens of concern (e.g. Salmonella) will be controlled by the heat treatment designed for Clostridium botulinum. A more severe heat treatment may be required to control spoilage bacteria. This should be verified in shelf life studies.

• cooling after heat treatment.

• refrigerated storage.

• specification for a maximum shelf life.

Hermetic sealing is required to prevent recontamination by other foodborne pathogens (e.g. Listeria) after heat treatment.

1.6 Examples of CCPs

It is not possible to present an exhaustive list of all CCPs required to control all hazards. In reality, one would need to be in specific food premise situation. However, an illustration of a number of CCPs follows. It [should be] is remembered that HACCP is product/process and plant specific.

TABLE 1 - BEEF BOURGUIGNON - EXAMPLES OF CCPs

2 FRESH STUFFED PASTA

2.1 Product Definition

Incoming materials as received:

• cooked meat stuffing (cooked in original package)

  pasteurized liquid eggs (refrigerated , in bulk)

• hard wheat semolina

• bread crumbs

• trays and plastic film

Important processing characteristics:

• preparation of ingredients before assembling

• heat treatment before packaging

• cooling before packaging

• modified atmosphere packaging

2.2 Intended use

• shelf life: 30 days

• must be cooked by end-user in boiling water as early as clearly indicated on product label. Cooking in boiling water will be equivalent or superior to 70°C for 2 min.

• to be kept under refrigeration at 4°C or less.

2.3 Process flow diagram

2.4 Hazard Identification

For stuffed pasta, many foodborne pathogens may be of concern. Listeria monocytogenes, as well as other pathogens (e.g., S. aureus, B. Cereus), should be considered since they may contaminate the product. Clostridium botulinum should be considered since it may come from raw ingredients and will not be completely inactivated by the heat treatment. Pathogens of concern are controlled by heat treatment, adherence to strict hygiene conditions and refrigerated storage.

2.5 Identification of Preventative Measures

Control of Listeria monocytogenes can be accomplished by:

• incoming materials as free as possible of such contamination

• heat treatment (minimum of 70°C for 2 minutes, internal temperature, or equivalent). A more severe heat treatment may be required to control spoilage bacteria. This should be verified in shelf life studies.

• adherence to strict hygiene conditions (as defined for High Risk Area) to prevent recontamination and growth

• hermetic sealing

• refrigerated storage

Control of Clostridium botulinum can be accomplished by:

• water activity less than 0.97 (for non-proteolytic strains)

• refrigerated storage (for proteolytic strains)

• specification for a maximum shelf life.

2.6 Examples of CCPs

It is not possible to present an exhaustive list of all CCPs required to control all hazards. In reality, one would need to be in specific food premise situation. However, an illustration of some CCPs follows. It [should be] is remembered that HACCP is product/process and plant specific.

TABLE 2 - FRESH STUFFED PASTA - EXAMPLES OF CCPs

3. ASSEMBLED SALAD

3.1 Product Definition

Incoming materials as received:

• cooked packaged potatoes (cooked in original package)

• canned tomatoes

• cooked packaged ham (cooked in origional package)

• peeled hard boiled eggs in MAP

• pickles

• mayonnaise (pH 4.0)

• trays and plastic film

Important processing characteristics:

• ingredients used as such and assembled

• packaged hermetically

• no further heat treatment after packaging

• maximum pH of final product: 4.8

3.2 Intended use

• shelf life: 15 days

• ready-to-eat, without any heating or cooking

• to be kept under refrigeration at 4°C or less

3.3 Process flow diagram

3.4 Hazard Identification

For this assembled salad, the foodborne pathogen of concern is Listeria monocytogenes. Other pathogens of concern can be controlled by either the low pH (4.8) or refrigerated storage.

3.5 Identification of Preventative Measures

Control of Listeria monocytogenes can be accomplished by:

• incoming materials as free as possible of such contamination

• adherence to strict hygiene conditions (as defined for High Risk Area) to prevent recontamination and growth

• control of pH

• refrigerated storage

• specification for a maximum shelf life.

3.6 Examples of CCPs

It is not possible to present an exhaustive list of all CCPs required to control all hazards. In reality, one would need to be in specific food premise situation. However, an illustration of a number of CCPs follows. It is to be remembered that HACCP is product/process and plant specific.

TABLE 3 - ASSEMBLED SALAD - EXAMPLES OF CCPs