|
December 31, 2001
NSF, in performing its functions in accordance with its objectives, does not assume or undertake to discharge any responsibility of the manufacturer or any other party. The opinions and findings of NSF represent its professional judgment. NSF shall not be responsible to anyone for the use of or reliance upon this Standard by anyone. NSF shall not incur any obligation or liability for damages, including consequential damages, arising out of or in connection with the use, interpretation of, or reliance upon this Standard.
NSF Standards provide basic criteria to protect the public health.
Participation in NSF Standards development activities by regulatory agency representatives (federal, local, state) shall not constitute their agency's endorsement of NSF or any of its Standards.
Preference is given to the use of performance criteria measurable by examination or testing in NSF Standards development when such performance criteria may reasonably be used in lieu of product design and information.
The illustrations, if provided, are intended to assist in understanding their adjacent standard requirements. However, the illustrations may not include all requirements for a specific method.
Unless otherwise referenced, the annexes are not considered an integral part of NSF Standards. The annexes are provided as general guidelines to the manufacturer, regulatory agency, user, laboratory, or certifying organization.
The purpose of NSF/ANSI 75 is to serve as a communication tool between manufacturers of product, retailers, and public health officials. This Standard provides test methods and evaluation criteria to allow for the determination that a food product meets FDA Food Code criteria for a "non-potentially hazardous food" and does not require refrigeration for safety. The Standard is intended to provide the mechanism for laboratory evidence to demonstrate that rapid and progressive growth of infectious or toxigenic microorganisms cannot occur. The Standard does not provide a means or methodology for determining whether a food has been adulterated. In fact, a food may be unsafe due to adulteration and still meet the criteria to be considered non-potentially hazardous per the definition in the FDA Food Code.
This Standard applies only to those items outlined in the scope. The scope of NSF/ANSI 75 has been carefully defined to include only a subset of non-potentially hazardous products, for which laboratory demonstration that the rapid and progressive growth of infectious or toxigenic microorganisms cannot occur, is routinely requested by retailers, regulators, and manufacturers.
The Standard also includes a list of products that have been specifically excluded from the scope. Some of these products are excluded because retailers and public health officials have not questioned whether these products should be refrigerated, such as white bread; bagels; donuts; muffins; individually preportioned, pre-wrapped snack cakes; and fruit filled pastries. Other products, such as those using modified atmosphere packaging, are excluded because they have been made shelf stable by their packaging and not by their formulation only. This
Standard does not address specialty-packaging techniques.
Suggestions for improvement of this Standard are welcome. Comments should be sent to Chair, Joint Committee on Non-potentially Hazardous Foods, c/o NSF International, Standards Department, P.O. Box 130140, Ann Arbor, Michigan, 48113-0140, USA.
This Standard will provide test methods and evaluation criteria to allow for the determination that a product does not require storage in a refrigerator for safety. This Standard is intended to provide the mechanism for laboratory evidence to demonstrate that the rapid and progressive growth of infectious or toxigenic microorganisms can not occur. This Standard does not provide a means or methodology for determining whether a food product has been adulterated. This Standard is intended only to be applied to the items indicated in the scope. It is not implied that products excluded from the scope of this Standard are innately safe.
This Standard contains requirements for food products that:
| I | Specialty breads or pastries containing fresh, canned, frozen, or rehydrated vegetables or soft cheeses added prior to baking. |
|---|---|
| II | Bakery products including specialty breads or pastries filled or topped with cream, creme, custard, or cheese after baking. |
| III | Products filled prior to baking such as pumpkin, sweet potato, custard or meringue pies. |
| IV | Toppings, glazes, icings, or fillings stored without temperature control prior to use in other products. |
The scope of this Standard also includes food products which meet the above requirements and are a component of a food product, are processed into a finished fully assembled form for sale or use by a food establishment, or have been processed into an unfinished, fully assembled form and are intended to be finished at a food establishment for sale or use by the food establishment.
This Standard does not apply to food products specified by the manufacturer for storage without temperature control for less than 24 hours or for 31 days or more. This Standard does not apply to meat, poultry, or seafood products or products which are a mixture of garlic with butter, margarine or oil.
The following bakery products are excluded from the scope of this Standard:
The following document contains provisions that, through reference in this text, constitute provisions of this Standard. At the time this Standard was written, the edition indicated was valid. All documents are subject to revision, and parties are encouraged to investigate the possibility of applying the recent edition of the document indicated below.
Terms used in this Standard that have special technical meaning are defined here.
3.1 challenge organism: A pathogenic organism which is intentionally inoculated into food for the purpose of testing whether the food will support growth of the organism within a specified time frame when stored without temperature control.
3.2 component: A food consisting of one or more ingredients which is intended to be used as part of a food product, e.g., a topping or filling for a pie.
3.3 consumer: A person who takes possession of a food product and is not functioning in the capacity of an operator of a food establishment or food processing plant.
3.4 finished product: A fully prepared, ready-to-eat food product.
3.5 food: Any raw, cooked, or processed edible substance, beverage, or ingredient intended for human consumption.
3.6 food establishment: An operation that stores, prepares, packages, serves, vends, sells, or otherwise provides food for human consumption.
3.7 fully assembled food product: A product in which all ingredients and components are combined by the manufacturer.
3.8 homogeneous product: A product having a uniform texture and content.
3.9 interface: A point at which two or more distinct components or ingredients meet.
3.10 lot: A quantity of product made with the same ingredients utilizing the same equipment in a continuous fashion at a specified manufacturing time.
3.11 manufacturer: The commercial operation that produces or manufactures the product.
3.12 master batch: A quantity of product which has been mixed with the inoculum to achieve the desired level of inoculation of challenge organisms, which will then be divided into individual samples for challenge testing.
3.13 organoleptic: Related to sensory evaluation including appearance, texture, aroma, and/or taste as related to product quality.
3.14 pH: The negative logarithm of the hydrogen ion concentration.
3.15 potentially hazardous food:3.16 special packaging: Packaging and related processing that may be used to render a product non-potentially hazardous.
3.17 temperature control: Maintaining a food product at a temperature of 60 °C (140 °F) or more or a temperature of 5 °C (41 °F) or less.
3.18 unfinished product: A product that requires further preparation before it is consumed.
3.19 water activity (aw): A measure of the free moisture in a food equal to the ratio of the water vapor pressure of a substance to the vapor pressure of pure water at the same temperature.
If a product is intended to be finished by a food establishment before being sold or used as a non-potentially hazardous food product, the manufacturer shall provide the food establishment with written instructions for handling and preparing the product to its finished form and for labeling the product as having met this Standard.
A non-potentially hazardous food product shall:
Each component of products in Categories I, II, and III shall be tested to determine the pH in accordance with 6.1. Each component shall be tested to determine the water activity in accordance with 6.2. If each component has a pH of 4.6 or less or each component has a water activity of 0.85 or less, then no further testing is required. If the product does not meet the acceptance criteria in 6.1.3 or 6.2.3, the product shall be tested in accordance with 6.3. The temperature during testing shall be 24 ± 2 °C (75 ± 3 °F). The relative humidity during testing shall be 45%-70%.
Products in Category IV shall be tested to determine the pH in accordance with 6.1. Products in Category IV shall be tested to determine the water activity in accordance with 6.2. If the product has a pH of 4.6 or less or a water activity of 0.85 or less, then no further testing is required. If the product does not meet the acceptance criteria in 6.1.3 or 6.2.3, the product shall be tested in accordance with 6.3. The temperature during testing shall be 24 ± 2 °C (75 ± 3 °F). The relative humidity during testing shall be 45%-70%.
The products shall be tested in accordance with figure 1. If pH is the only factor rendering the product non-potentially hazardous, the product shall be tested in accordance with 6.1. If water activity is the only factor rendering the product non-potentially hazardous, it shall be tested in accordance with 6.2. If other factors, including a combination of reduced pH and water activity, render the product non-potentially hazardous, it shall be tested in accordance with 6.3. Annex A is informative and provides a flowchart of the test methods.
If pH is the sole factor to render the product non-potentially hazardous, the pH of the food product shall be 4.6 or less.
If the product is in an unfinished form, the product shall be prepared according to the manufacturer's instructions except that the product shall be baked/cooked for 100% of the manufacturer's lowest recommended time and at the manufac-turer's lowest recommended temperature.
The pH of three representative product samples shall be measured. If the product is nonhomogeneous, the pH of three samples of each component shall be measured.
The pH shall be measured in accordance with the methods in sections 8.6 and 8.7 of the Compendium of Methods for the Microbiological Examination of Foods at 24 ± 2 °C (75 ± 3 °F) using an instrument with an accuracy of ± 0.01 pH unit or better.
The pH of each sample of each component measured shall be 4.6 or less.
If water activity is the sole factor to render the product non-potentially hazardous, the water activity of the food product shall be 0.85 or less.
If the product is in an unfinished form, the product shall be prepared according to the manufacturer's instructions except that the product shall be baked/cooked for 100% of the manufacturer's lowest recommended time at the manufacturer's lowest recommended temperature.
The water activity of three representative product samples shall be measured. If the product is nonhomogeneous, the water activity of three samples of each component shall be measured.
The water activity shall be measured in accordance with the methods in sections 8.1 - 8.5 of the Compendium of Methods for the Microbiological Examination of Foods at 24 ± 2 °C (75 ± 3 °F) using an instrument capable of achieving a standard deviation of ± 0.005 or less.
The water activity of each sample of each component measured shall be 0.85 or less.
This test shall be conducted to evaluate if a food product is capable of supporting the rapid and progressive growth of a composite of 5 strains of challenge organisms inoculated into the product. Prior to testing, the pH and water activity of the product shall be measured in accordance with 6.1 and 6.2.
The challenge organisms for a particular product shall be determined in accordance with table 1. The product shall be evaluated for 1.3 times the length of time specified by the manufacturer that the product in its finished form may be stored outside of temperature control without special packaging (any partial day shall be rounded up to a full day). The time points shall be determined in accordance with table 2. The to organism counts shall be determined two hours after inoculation.
A separate inoculum shall be prepared for each genus of challenge organisms. The inoculum for each organism shall contain a mixture of the five strains specified in table 3. All test strains shall be obtained directly from the ATCC or relevant source and revived, if necessary, according to the instructions provided with the culture. Cultures shall be maintained according to standard laboratory practices for culture maintenance.
As required, the inocula for Salmonella spp., Listeria monocytogenes, Escherichia coli O157:H7, and Staphylococcus aureus shall be prepared in accordance with 6.3.2.1. The inoculum for Bacillus cereus shall be prepared in accordance with 6.3.2.2. The inoculum for Clostridium perfringens shall be prepared in accordance with 6.3.2.3.
A cell suspension shall be prepared for each strain in the inoculum. Each cell suspension shall be prepared by the following method: a pure culture of the strain shall be inoculated into one or more tubes of Trypticase Soy Broth. The broth shall be incubated for 24 ± 2 h at 35 ± 2 °C (95 ± 3 °F). The cell suspensions from each strain shall be mixed to prepare an inoculum, which contains an approximately equal number of cells of each strain. As necessary, the suspensions may be diluted in Butterfield's Phosphate Buffer dilution water prior to determining the concentration of the inoculum. The concentration of the inoculum shall be standardized using the spread plating method.
A suspension containing both vegetative cells and spore forms shall be prepared for each strain in the inoculum. Each suspension shall be prepared by the following method: a pure culture of the strain shall be inoculated into one or more tubes of Trypticase Soy Broth. The broth shall be incubated for 24 ± 2 h at 35 ± 2 °C (95 ± 3 °F). After incubation, the broth shall be used to inoculate the surface of Tryptic Soy Agar (TSA). The agar shall be incubated for 24 ± 2 h at 35 ± 2 °C (99 ± 3 °F). The suspensions from each strain shall be mixed to prepare an inoculum, which contains an approximately equal number of cells of each strain. As necessary, the suspensions may be diluted in Butterfield's Phosphate Buffer dilution water prior to determining the concentration of the inoculum. The concentration of the inoculum shall be standardized using the spread plating method.
A suspension containing both vegetative cells and spore forms shall be prepared for each strain in the inoculum. Each suspension shall be prepared by the following method: A pure culture of the strain shall be inoculated into one or more tubes of Fluid Thioglycollate Broth. The broth shall be incubated for 48 to 96 h at 35 ± 2 °C (95 ± 3 °F). At 48 h, 72 h and 96 h, microscopic examination of the broth shall be performed to determine whether free spores or cells with prespores are present. When the broth contains 10%-50% free spores and cells with prespores, incubation is complete. The suspensions from each strain shall be mixed to prepare an inoculum, which contains an approximately equal number of cells of each strain. As necessary, the suspensions may be diluted in Butterfield's Phosphate Buffer dilution water prior to determining the concentration of the inoculum. The concentration of the inoculum shall be standardized using the spread plating method.
If the product is in an unfinished form, the product shall be prepared according to the manufacturer's instructions except that the product shall be baked/cooked for 100% of the manufacturer's lowest recommended time at the manufacturer's lowest recommended temperature.
When necessary, the product shall be brought to a temperature of 24 ± 2 °C (75° ± 3 °F) before samples are prepared.
At a minimum, two control samples shall be prepared to evaluate changes in the pH, water activity, aerobic plate count, and yeast and mold count of the product during the test period.
To prepare control samples for products in Categories I, II, and III, the sample shall be sliced into a sufficient number of slices to evaluate the sample for the presence of the challenge organisms occurring naturally and to evaluate the sample for the above parameters at the first time point (Day 0) and at the last time point. The sample slices shall be repackaged according to the procedures in 6.3.3.2.4.1.
To prepare each control sample for products in Category IV, a sufficient amount of product to evaluate the sample for the presence of the challenge organisms occurring naturally, and to evaluate the sample for the above parameters at the first time point (Day 0) and at the last time point, shall be aseptically weighed into a sterile container or stomacher bag. The two control samples shall be incubated at 24 ± 2 °C (75 ± 3 °F).
Test samples shall be prepared to evaluate the ability of the product to support the rapid and progressive growth of a composite of 5 strains of challenge organisms inoculated into the product.
Separate test samples shall be prepared for each composite of challenge organisms. The to time point shall have 5 samples prepared according to the procedures in 6.3.3.2.4 and 6.3.3.2.5. The formula shall be as follows:
| 5 test samples | x | 3 different lots | x | 15 samples needed per product at t0 |
Separate test samples shall be prepared for each composite of challenge organisms. For each time point, samples shall be prepared and inoculated in accordance with the procedures in 6.3.3.2.4. For products large enough to provide two samples, one product will be needed for each time point. For example, a cake may contain two slices. Each slice is one sample. For products too small to provide two samples, multiple products may be used. During the storage test, each product will be stored in accordance with the procedures in 6.3.3.2.4.1. To determine the total number of products needed per composite of challenge organisms, refer to table 2 to determine the number of time points and complete the formula:
| number of products to provide 2 samples | x | 3 different lots | x | number of time points per table 2 | = | number of products needed |
For each time point, samples shall be prepared and inoculated in accordance with the procedures in 6.3.3.2.5. To determine the number of samples needed per composite of challenge organisms, refer to table 2 to determine the number of time points and complete the formula:
| 2 test samples | x | 3 different lots | x | number of time points per table 2 | = | number of samples needed |
Samples shall then be incubated for the specified time points. Following removal at each time point, each sample shall be analyzed according to the procedures in 6.3.4.2.
Each product shall be removed from the package and divided with a sterile knife into uniform slices. The weight of each slice shall be taken and the average weight shall be determined in order to calculate the amount of inoculum required to achieve a final level of 10,000 cfu/gm. Each component shall be inoculated at the product slice by micropipettor with a fraction of the total inoculum volume. For example, if a product has four components, each component shall be inoculated with ¼ of the total inoculum. Annex A is informative and provides illustrations of inoculation techniques.
Following inoculation, the slices of the product shall be reassembled into the original shape of the product and repackaged to resemble the original packaging per the manufacturer's recommendation. The product will be stored in the repackaged state during the storage time until it is evaluated. Manufacturers may need to provide additional packaging materials.
For each composite of challenge organisms, a master batch for each lot of product shall be prepared to include sufficient product to include all time points for testing of the product according to table 2. The master batch shall be thoroughly mixed in a stomacher with the inoculum prior to dispensing into 25 gram samples. The mixing time shall vary in accordance with the texture of the product. Care must be taken to produce an adequate distribution of organisms in the product. Product may require extended mixing. However, separation of individual components or excessive heating of components shall not occur. From this master batch, a sufficient amount of 25 gram samples shall be dispensed into a sterile container or stomacher bag to complete the time point storage study. The inoculum value for the master batch shall allow for a final inoculum value for each 25 gram sample to be 2 x 103 - 5 x 10 4 cfu/g. Samples of each product shall then be incubated for the specified time points.
Following removal at each time point, each sample shall be analyzed according to procedures in 6.3.4.2.
The test samples shall be incubated at 24 ± 2 °C (75 ± 3 °F).
On Day 0 (the day of inoculation), the control samples shall be evaluated for the presence of naturally occurring challenge organisms in accordance with the methods outlined in 6.3.4.2.
On Day 0 and at the last time point, the pH, temperature, water activity, aerobic plate count, and yeast and mold count of at least two control samples shall be measured. The pH and water activity shall be evaluated in accordance with 6.1 and 6.2. To determine the aerobic plate count and yeast and mold count of each sample, a representative 25-gram portion shall be aseptically weighed into a sterile container or stomacher bag. 225 ml of sterile Butterfield's Phosphate Buffer shall be added to the 25-gram sample and the mixture shall be blended for two minutes. Tenfold dilutions of the homogenate shall be prepared in Butterfield's Phosphate Buffer. To determine the aerobic plate count, the dilutions shall be pour plated on plate count agar. To determine the yeast and mold count, the dilutions shall be pour plated on plate count agar with 100 ug/ml chloramphenicol.
The number of cfu/gram of each challenge organism shall be determined for the 2 test samples per lot inoculated with the organism at each time point except for the to time point at which 5 samples shall be examined. Where there are applicable enumeration methods by AOAC, they shall be used. Duplicate plate counts shall be performed.
The following methods shall be used to determine the challenge organism counts:
The average count of Salmonella spp., Listeria monocytogenes, Bacillus cereus, Clostridium perfringens, Staphylococcus aureus, or Escherichia coli 0157:H7 shall not increase more than 1 log for two consecutive time points or more than 1 log by the last time point compared to the average count on Day 0. The average count shall be the geometric mean value of two samples per lot for each time point. The geometric mean shall be derived from reducing each value to its logarithm, adding these values and dividing by the number of determinations to obtain the log average. The antilog of the log average then gives a real number which is the best estimate of the population.
The challenge test will be discontinued if the visual or odor criteria for quality of the product is not met.
| Minimum pH of product components | Minimum aw of product components | Challenge organism |
|---|---|---|
| > 4.6 | > 0.85 | Staphylococcus aureus |
| > 5.0 | > 0.93 | Bacillus cereus |
| > 4.6 | > 0.94 | Salmonella spp. |
| > 4.6 | > 0.95 | Escherichia coli O157:H7 |
| > 4.6 | > 0.92 | Listeria monocytogenes |
| > 5.5 | > 0.93 | Clostridium perfringens |
Reference: Microorganisms in Food 5, Chapman and Hall, 1996 for pH and water activity requirements of organisms.
| Test duration | Time points |
|---|---|
| 24 h -5 d | 1-5 time points, every 24 h starting with point 0 |
| 6 - 14 d | 5 time points, every 1 -3 d starting with point 0 |
| 15 - 21 d | 6 time points, every 3 -4 d starting with point 0 |
| 22 - 31 d | 7-10 time points, every 3 d starting with point 0 |
| 32 - 40 d | 8-10 time points, every 4 d starting with point 0 |
| Challenge organism | Required strains |
|---|---|
| Bacilillus cereus | ATCC 33018 |
| ATCC 49063 | |
| ATCC 49064 | |
| ATCC 95992 | |
| SLRCC 1361 | |
| Escherichia coli O157:H7 ATCC 43895 | |
| ATCC 35150 | |
| ATCC 43890 | |
| ATCC 43894 | |
| ATCC 43888 | |
| Listera monocytogenes ATCC 51414 | |
| ATCC 51775 | |
| ATCC 51779 | |
| SLRCC 525 | |
| SLRCC 518 | |
| Salmonella spp. SLRCC 1468 | |
| SLRCC 143 | |
| SLRCC 1434 | |
| SLRCC 539 | |
| SLRCC 1443 | |
| Staphyococcus aureus ATCC 51740 | |
| ATCC 13565 | |
| ATCC 27664 | |
| ATCC 13567 | |
| ATCC 51811 | |
| Clostridium perfingens ATCC 8679 (SC9) | |
| SLRCC 1154 | |
| SLRCC 1155 | |
| SLRCC 1156 | |
| SLRCC 1157 |
ATCC denotes American Type Culture Collection. SLRCC denotes Silliker Laboratories Research Culture Collection.
NOTE - If more appropriate isolates are identified for particular applications, they will be added to the Standard.
| Points of inoculation |
|---|
| 1. Meringue |
| 2. Fillig & Meringue Interface |
| 3. Filling |
| 4. Filling & Crust Interface |
| 5. Crust |
| Points of inoculation |
|---|
| 1. Bread |
| 2. Bread & Cheese Interface |
| 3. Cheese |
| 4. Cheese & Vegetable Interface |
| 5. Vegetable |
| 6. Bread & Vegetable |
The following standards and criteria established and adopted by NSF as minimum voluntary consensus standards are used internationally:
2 Food equipment
3 Commercial warewashing equipment
4 Commercial cooking, rethermalization, and powered hot food holding and transport equipment
5 Water heaters, hot water supply boilers, and heat recovery equipment
6 Dispensing freezers
7 Commercial refrigerators and freezers
8 Commercial powered food preparation equipment
12 Automatic ice making equipment
13 Refuse processors and processing systems
14 Plastics piping system components and related materials
18 Manual food and beverage dispensing equipment
20 Commercial bulk milk dispensing equipment
21 Thermoplastic refuse containers
24 Plumbing system components for manufactured homes and recreational vehicles
25 Vending machines for food and beverages
29 Detergent and chemical feeders for commercial spray-type dishwashing machines
35 High pressure decorative laminates (HPDL) for surfacing food service equipment
36 Dinnerware
37 Air curtains for entranceways in food and food service establishments
40 Residential wastewater treatment systems
41 Non-liquid saturated treatment systems
42 Drinking water treatment units - Aesthetic effects
44 Residential cation exchange water softeners
46 Evaluation of components and devices used in wastewater treatment systems
49 Class II (laminar flow) biohazard cabinetry
50 Circulation system components and related materials for swimming pools, spas/hot tubs
51 Food equipment materials
52 Supplemental flooring
53 Drinking water treatment units - Health effects
55 Ultraviolet microbiological water treatment systems
58 Reverse osmosis drinking water treatment systems
59 Mobile food carts
60 Drinking water treatment chemicals - Health effects
61 Drinking water system components - Health effects
62 Drinking water distillation systems
75 Non-potentially hazardous foods
116 Non-food compounds used in food processing facilities - Food grade lubricants (draft standard for trial use)
173 Dietary supplements (draft standard for trial use)
184 Residential dishwashers
14159 Safety of machinery - Hygiene requirements for the design of machinery
14159-1 Hygiene requirements for the design of meat and poultry processing equipment
C-2 Special equipment and/or devices
1The information contained in this Disclaimer is not part of this American National Standard (ANS) and has not been processed in accordance with ANSI's requirements for an ANS. As such, this Disclaimer may contain material that has not been subjected to public review of a consensus process. In addition, it does not contain requirements necessary for conformance to the Standard.
2The information contained in this Foreword is not part of this American National Standard (ANS) and has not been processed in accordance with ANSI's requirements for an ANS. As such, this Foreword may contain material that has not been subjected to public review of a consensus process. In addition, it does not contain requirements necessary for conformance to the Standard.
3AOAC International, 481 N. Frederick Avenue, Suite 500, Gaithersburg, MD 20877
4American Public Health Association (APHA), 1015 Fifteenth Street NW, Washington, DC 20005
5U.S. Department of Health and Human Services, Public Health Service, Food and Drug Administration, Washington, DC 20204
6The information contained in this Annex is not part of this American National Standard (ANS) and has not been processed in accordance with ANSI's requirements for an ANS. As such, this Annex may contain material that has not been subjected to public review of a consensus process. In addition, it does not contain requirements necessary for conformance to the Standard.
7The information contained in this Standards and Criteria page is not part of this American NationalStandard (ANS) and has not been processed in accordance with ANSI's requirements for an ANS. As such, this Standards and Criteria page may contain material that has not been subjected to public review of a consensus process. In addition, it does not contain requirements necessary for conformance to the Standard.
Figure 1 - Test Methods
Description: Figure 1 – Test Methods is a decision tree diagram describing the procedural steps used in NSF Standard 75 to determine if a food is non-potentially hazardous food. Once the product to be tested is prepared according to the manufacturer’s instructions, the pH of each component is determined by approved methods in either 3 representative samples or 3 samples of each component for a non-homogeneous product. If the pH of each component is equal to or less than pH 4.6, the product passes or is non-potentially hazardous food. If the pH of any component is greater than pH 4.6, the product fails and the next step is to determine the water activity.
The approved water activity test method uses the same sampling procedure for non-homogeneous products as the pH testing method. If the water activity of each component is equal to or less than 0.85, the product passes or is non-potentially hazardous food. If the water activity of any component is greater than 0.85, the product fails and a microbiological challenge test must be performed.
The challenge test is used to evaluate products that cannot use pH or water activity alone to declare the food non-potentially hazardous food. The challenge organism is selected based on the minimum pH and water activity of the product components (see Table 1). Five separate strains of the chosen challenge organism (see Table 3) are used in the testing inoculum. Test duration and time points for testing over 1.3 times the shelf life proposed by the manufacturer are shown in Table 2. The product then passes as non-potentially hazardous product if growth of the selected challenge organism is equal to or less than 1 log for each sample or growth exceeding 1 log only occurs at one time point other than the end product. If growth of the selected challenge organism is greater than 1 log for any two time points or at the end point, the product fails and must be refrigerated as potentially hazardous food.
