On this page
- Introduction
- Control of Clostridium botulinum in fermented meat products
- Control of Staphylococcus aureus in fermented meat products
- E. coli and Salmonella control options in fermented sausages
- Control of pathogens in dried products
- Control of E. coli O157 in dried beef products
- Shelf stable fermented and dried meat products
Introduction
The purpose of this document is to provide information on measures for controlling the risk of pathogens in fermented and dried meat products.
Control of Clostridium botulinum in fermented meat products
In order to minimize the danger of outgrowth of Clostridium botulinum spores and development of the botulinal toxin in fermented meat products, nitrite/nitrate are added at a minimum level of 100 ppm along with a minimum of 2.5% of salt.
Control of Staphylococcus aureus in fermented meat products
Background
Certain strains of the bacteria Staphylococcus aureus are capable of producing a highly heat stable toxin that causes illness in humans. Above a critical temperature of 15.6°C, Staphylococcus aureus multiplication and toxin production can take place. Once a pH of 5.3 is reached, Staphylococcus aureus multiplication and toxin production are stopped.
Degree-hours are the product of:
- time (as measured in hours at a particular temperature)
multiplied by - degrees Celsius (measured in excess of 15.6°C, the critical temperature for growth of Staphylococcus aureus)
Degree-hours are calculated for each temperature used in the process. The limitation of the number of degree-hours depends upon the highest temperature in the fermentation process prior to the time that a pH of 5.3 or less is attained.
The operator is encouraged to measure temperatures at the surface of the product. Where this is not possible, the operator should utilize fermentation room temperatures. The degree hour calculations are based on fermentation room temperatures. Temperature and humidity should be uniform throughout the fermentation room.
A process can be judged as acceptable provided the product consistently reaches a pH of 5.3 using:
- fewer than 665 degree-hours when the highest fermentation temperature is less than 33°C;
- fewer than 555 degree-hours when the highest fermentation temperature is between 33°C and 37°C; and
- fewer than 500 degree-hours when the highest fermentation temperature is greater than 37°C.
Fermentation done at a constant temperature (Constant Temperature Process)
When fermentation is done at a constant temperature, operators can either use the following table or the calculation method (see examples below) for determining degree-hours limits and maximum time for fermentation at a given room temperature.
| Degree-hours limit for the corresponding temperature | Fermentation room temperature (°C) | Maximum allowed hours to achieve a pH of 5.3 |
|---|---|---|
| 665 | 20 | 150.0 |
| 665 | 22 | 103.4 |
| 665 | 24 | 78.9 |
| 665 | 26 | 63.8 |
| 665 | 28 | 53.6 |
| 665 | 30 | 46.2 |
| 665 | 32 | 40.5 |
| 555 | 33 | 31.8 |
| 555 | 34 | 30.1 |
| 555 | 35 | 28.6 |
| 555 | 36 | 27.2 |
| 555 | 37 | 25.9 |
| 500 | 38 | 22.3 |
| 500 | 40 | 20.5 |
| 500 | 42 | 18.9 |
| 500 | 44 | 17.6 |
| 500 | 46 | 16.4 |
| 500 | 48 | 15.4 |
| 500 | 50 | 14.5 |
How to use the calculation method for constant temperature processes
Example 1
Fermentation room temperature is a constant 26°C. It takes 55 hours for the pH to reach 5.3.
Degrees above 15.6°C: 26°C - 15.6°C = 10.4°C
Hours to reach pH of 5.3:55
Degree-hours calculation: (10.4°C) × (55) = 572 degree-hours
The corresponding degree-hours limit (less than 33°C) is 665 degree-hours.
Conclusion: Example 1 meets the guideline because its degree-hours are less than the limit.
Example 2
Fermentation room temperature is a constant 35°C. It takes 40 hours for the pH to reach 5.3.
Degrees above 15.6°C: 35°C - 15.6°C = 19.4°C
Hours to reach pH of 5.3: 40
Degree-hours calculation: (19.4°C) × (40) = 776 degree-hours
The corresponding degree-hours limit (between 33 and 37°C) is 555 degree-hours.
Conclusion: Example 2 does not meet the guideline because its degree-hours exceed the limit. Hold the product and refer to Disposition of lots which have not met degree-hours limits below.
Fermentation done at different temperatures (Variable Temperature Process)
When the fermentation takes place at various temperatures, each temperature step in the process is analyzed for the number of degree-hours it contributes. The degree-hours limit for the entire fermentation process is based on the highest temperature reached during fermentation.
Example 1
It takes 35 hours for product to reach a pH of 5.3 or less. Fermentation room temperature is 24°C for the first 10 hours, 30°C for second 10 hours and 35°C for the final 15 hours.
Step 1
Degrees above 15.6°C: 24°C - 15.6°C = 8.4°C
Hours to reach pH of 5.3: 10
Degree-hours calculation: (8.4°C) × (10) = 84 degree-hours
Step 2
Degrees above 15.6°C: 30°C - 15.6°C = 14.4°C
Hours to reach pH of 5.3: 10
Degree-hours calculation: (14.4°C) × (10) = 144 degree-hours
Step 3
Degrees above 15.6°C: 35°C - 15.6°C = 19.4°C
Hours to reach pH of 5.3: 15
Degree-hours calculation: (19.4°C) × (15) = 291 degree-hours
Degree-hours calculation for the entire fermentation process = 84 + 144 + 291 = 519
The highest temperature reached = 35°C
The corresponding degree-hour limit = 555 (between 33°C and 37°C)
Conclusion: Example 1 meets the guideline because its degree-hours are less than the limit.
Example 2
It takes 38 hours for product to reach a pH of 5.3 or less. Fermentation room temperature is 24°C for the first 10 hours, 30°C for the second 10 hours and 37°C for the final 18 hours.
Step 1
Degrees above 15.6°C: 24°C - 15.6°C = 8.4°C
Hours to reach pH of 5.3: 10
Degree-hours calculation: (8.4°C) × (10) = 84 degree-hours
Step 2
Degrees above 15.6°C: 30°C - 15.6°C = 14.4°C
Hours to reach pH of 5.3: 10
Degree-hours calculation: (14.4°C) × (10) = 144 degree-hours
Step 3
Degrees above 15.6°C: 37°C - 15.6°C = 21.4°C
Hours to reach pH of 5.3: 18
Degree-hours calculation: (21.4°C) × (18) = 385.2 degree-hours
Degree-hours calculation for the entire fermentation process = 84 + 144 + 385.2 = 613.2
The highest temperature reached = 37°C
The corresponding degree-hour limit = 555 (between 33°C and 37°C)
Conclusion: Example 2 does not meet the guidelines because its degree-hours exceed the limit; hold the product and refer Disposition of lots which have not met degree-hours limits below.
Disposition of lots which have not met degree-hours limits
When an operator is conducting a product risk assessment because they intend to distribute a product for which the degree-hours limit has been exceeded, consideration should be given to the following:
- Test the implicated lots for Staphylococcus aureus and its enterotoxin, and for principal pathogens, such as E. coli O157:H7, Salmonella, Clostridium botulinum and Listeria monocytogenes, after the drying period has been completed.
- If the bacteriological evaluation proves that there are fewer than 104 Staphylococcus aureus per gram and that no enterotoxin or other pathogens are detected, then the product may be sold provided that it is labelled as requiring refrigeration. When Staphylococcus aureus levels are higher than 104 per gram with no enterotoxin present, the product may be used in the production of a cooked product - but only if the heating process achieves full lethality applicable to the meat product.
- Destroy the product when Staphylococcus aureus enterotoxin is detected in the product.
E. coli and Salmonella control options in fermented sausages
In order to suitably control these hazards and prevent incidents of food borne disease, facilities who manufacture fermented sausages can use one of the five following options for the control of verotoxinogenic E. coli including E. coli O157:H7 and Salmonella when they:
- use beef as an ingredient in a dry or semi-dry fermented meat sausage;
- store or handle uncooked beef on site;
- obtain raw meat from a supplying facility which stores or handles uncooked beef on site.
Facilities which do not use beef and do not obtain meat ingredients from facilities which handle beef are not currently required to use one of the five options for the control of E. coli O157:H7 in dry/semi-dry fermented sausages. However, they must validate through a microbiological testing program that their process will not result in the presence of E. coli O157:H7 or Salmonella in the finished product.
Option 1
Include as part of the manufacture of the sausage, one of the following heat processes which are recognized as controlling E. coli O157:H7.
Note: Under this option, it is not required to test for E. coli O157:H7.
| Minimum internal temperature maintained during the entire process | Minimum processing time in minutes after the minimum temperature has been reached |
|---|---|
| 130°F (54.4°C) | 121 |
| 131°F (55°C) | 97 |
| 132°F (55.6°C) | 77 |
| 133°F (56.1°C) | 62 |
| 134°F (56.7°C) | 47 |
| 135°F (57.2°C) | 37 |
| 136°F (57.8°C) | 32 |
| 137°F (58.4°C) | 24 |
| 138°F (58.9°C) | 19 |
| 139°F (59.5°C) | 15 |
| 140°F (60°C) | 12 |
| 141°F (60.6°C) | 10 |
| 142°F (61.1°C) | 8 |
| 143°F (61.7°C) | 6 |
| 144°F (62.2°C) | 5 |
| 145°F (62.8°C) | 4 |
Option 2
Use a manufacturing process (combination of fermentation, heating, holding and/or drying) which has already been scientifically validated to achieve a 5 log10 (5D) reduction of E. coli O157:H7.
Manufacturing processes used to make fermented sausages are only considered effective against E. coli O157:H7 if it is shown that they achieve a 5 log10 (5D) reduction or greater of E. coli O157:H7. The manufacturing process used is evaluated in a scientific manner consistent with the challenge study recommendations (refer to Option 5) of this section.
Under this option, testing each lot for E. coli O157:H7 or Salmonella is not needed. The operator will implement a microbiological testing program for E. coli 0157 and Salmonella as a verification procedure for their process.
The following processes have been scientifically validated as achieving a 5 log10 (5D) or greater reduction of E. coli O157:H7.
| Fermentation chamber temperature | pH at the end of fermentation process | Casing diameter | Subsequent process (dry, hold or cook) | Reference |
|---|---|---|---|---|
| 70°F (21°C) | > 5.0 | < 55 mm | heat (1 hr @ 110°F and 6 hrs @ 125°F) | |
| 90°F (32°C) | < 4.6 | < 55 mm | hold @ 90°F for > 6 days | |
| 90°F (32°C) | < 4.6 | < 55 mm | heat (1 hr @ 110°F then 6 hrs @ 125°F) | |
| 90°F (32°C) | < 4.6 | 56 to 105 mm | heat (1 hr @100°F, 1 hr @ 110°F, 1 hr @ 120°F, then 7 hrs @ 125°F) | |
| 90°F (32°C) | > 5.0 | 56 to 105 mm | heat (1 hr @100°F, 1 hr @ 110°F, 1 hr @ 120°F, then 7 hrs @ 125°F) | |
| 96°F (36°C) | < 5.0 | < 55 mm | heat (1 hr @ 128°F internal product temperature) and dry (at 55°F and 65% relative humidity to a moisture protein ratio of < 1.6:1) | |
| 110°F (43°C) | < 4.6 | < 55 mm | hold @ 110°F for > 4 days | |
| 110°F (43°C) | < 4.6 | 56 to 105 mm | hold @ 110°F for > 4 days | |
| 110°F (43°C) | > 5.0 | 56 to 105 mm | hold @ 110°F for > 7 days |
Table Notes
- Table note 1
-
Nicholson, R., et al, Dry fermented sausage and Escherichia coli O157:H7. National Cattlemen's Beef Association, Research Report Number 11-316, Chicago, Illinois, 1996.
- Table Note 2
-
Hinkens, J.C., et al, Validation of Pepperoni Processes for Control of Escherichia coli O157:H7, Journal of Food Protection, Volume 59, Number 12, 1996, pp. 1260-1266.
Option 3
Where the manufacturing process does not correspond to one of the processes set out under options 1, 2 or 4 of this section and has not been assessed in accordance with option 5 of this section, hold and test each production lot pending satisfactory results.
- The definition of lot for the purposes of sampling must be statistically sound and must correspond to product manufactured under the same conditions. A lot cannot exceed a single day's production.
- For each lot, the operator must take 30 samples of finished product and submit them for analysis. The sampling plan must be representative of the lot.
- Each sample must consist of at least 25 g of product. Samples must be taken in accordance with standard microbiological techniques to avoid contamination of product. Sampling of intact product packages is strongly recommended. It is unacceptable to take multiple samples from one intact package as this is not considered statistically representative of the lot.
- It is acceptable to combine a maximum of three (3) samples into a composite for purposes of analysis when testing is done for E. coli O157:H7 and Salmonella.
- At a minimum, each composite sample must be tested for the presence of E. coli O157:H7 and Salmonella.
- The method used to analyse the end product samples must be one of the methods listed in Health Canada's Compendium of Analytical Methods, Volume 3, Laboratory Procedures for the Microbiological Analysis of Foods (ISBN 0-921317-17-4).
- Results must be reported in writing, identified as to the lot of product being tested and must include individual results for each test performed, method used and minimum sensitivity of the test used.
- Product will be held under the control of the operator until the written results of analysis have been received. In order to be released, all tests must be negative for the presence of E. coli O157:H7 and Salmonella and any other pathogens tested.
- In case of a positive result for either E. coli O157:H7 or Salmonella or another pathogen the entire lot must be held and either submitted to an accepted lethality process or be destroyed. Possible cross-contamination of other lots must also be assessed.
Option 4
This option entails a microbiological testing program of raw meat and batter for E. coli O157:H7 and Salmonella as part of the operator's HACCP-based system and a manufacturing process (fermentation and holding, heating and/or drying) which has been scientifically validated as achieving at least 2 log10 (2D) reduction of E. coli O157:H7.
Manufacturing processes used to make fermented sausages are considered partially effective against E. coli O157:H7 if it is shown that they achieve 2 log10 (2D) reduction to 5 log10 (5D) reduction of E. coli O157:H7. The manufacturing process used is evaluated in a scientific manner consistent with the challenge study recommendations (refer to Option 5). A number of manufacturing processes have been scientifically demonstrated as achieving a 2 log10 (2D) reduction to 5 log10 (5D) reduction. The sampling program must be in accordance with the following requirements:
- The definition of lot for the purposes of sampling must be statistically sound and must correspond to product manufactured under the same conditions. A lot cannot exceed a single day's production. Provided that effective controls for tracing product are in place and all corresponding dry fermented sausage manufacturing processes have been validated as achieving at least a 2 log10 (2D) reduction of E. coli O157:H7, it would be acceptable to conduct one single series of sampling on batter which is used in different sausages. A lot cannot exceed one day's production of raw batter.
- For each lot, the operator must take 15 samples of raw batter and submit them for analysis. The sample plan must be representative of the lot.
- Each sample must consist of at least 25 g of product. Samples must be taken in accordance with standard microbiological techniques to avoid contamination of product. Sampling of intact product packages is strongly recommended. It is unacceptable to take multiple samples from one intact package as this is not considered statistically representative of the lot.
- It is acceptable to combine a maximum of three (3) samples into a composite for purposes of analysis when testing is done for E. coli O157:H7 and Salmonella.
- At a minimum, each composite sample must be tested for the presence of E. coli O157:H7 and Salmonella.
- The method used to analyse the end product samples must be one of the methods listed in Health Canada's Compendium of Analytical Methods, Volume 3, Laboratory Procedures for the Microbiological Analysis of Foods (ISBN 0-921317-17-4).
- Results must be reported in writing, identified as to the lot of product being tested and must include individual results for each test performed, method used and minimum sensitivity of the test used.
- Product will be held under the control of the operator until the written results of analysis have been received. In order to be released, all tests must be negative for the presence of E. coli O157:H7 and Salmonella and any other pathogens tested.
- In case of a positive result for either E. coli O157:H7 or Salmonella or another pathogen the entire lot must be held and either submitted to an accepted lethality process or be destroyed. Possible cross-contamination of other lots must also be assessed. For reference, the following methods have been scientifically documented as achieving a minimum 2 log10 (2D) reduction in E. coli O157:H7.
| Fermentation chamber temperature | pH at the end of fermentation | Casing diameter | Subsequent process (dry, hold or cook) | Reference |
|---|---|---|---|---|
| 70°F (21°C) | > 5.0 | 56 to 105 mm | heat(1 hr @ 110°F and 6 hours @ 125°F) | |
| 90°F (32°C) | < 4.6 | 56 to 105 mm | hold @ 90°F for 7 days then dry | |
| 90°F (32°C) | > 5.0 | 56 to 105 mm | hold @ 90°F for 7 days then dry | |
| 110°F (43°C) | > 5.0 | < 55 mm | hold @ 110°F for 7 days then dry | |
| 110°F (43°C) | > 5.0 | 56 to 105 mm | heat (1 hr @ 110°F and 6 hours @ 125°F) |
Table Note
- Table note 3
-
Nicholson, R., et al, Dry fermented sausage and Escherichia coli O157:H7. National Cattlemen's Beef Association, Research Report Number 11-316, Chicago, Illinois, 1996.
Option 5
This option is a validation challenge study to demonstrate that the manufacturing process achieves as 5 log10 (5D) reduction of E. coli O157:H7.
Facilities which elect to use this option to demonstrate that their manufacturing process achieves a 5 log10 (5D) reduction of E. coli O157:H7, may be able to manufacture product according to the requirements of Option 2 (e.g., not be required to test each lot of product for E. coli O157:H7 and Salmonella). Alternatively, if their manufacturing process achieves a 2 log10 (2D) reduction of E. coli O157:H7 they may be able to manufacture product according to the requirements of Option 4 (e.g., HACCP-based system and testing of raw batter).
Challenge Study Protocol
- This validation should not be conducted within an actual food manufacturing facility. Work should be conducted in a Biosafety level II facility by appropriately trained personnel. Following use, autoclave all inoculated product and sanitize processing equipment. Follow appropriate procedures for the disposal of waste.
- Types and numbers of strains of E. coli O157:H7 to use as an inoculum: At least five (5) strains of E. coli O157:H7 should be used including representatives of strains associated with human illness and strains isolated from meat and poultry products. One isolate from an outbreak associated with a dry fermented sausage product must be included.
- Methods of production, enumeration and standardization of inoculum: Individual cultures of each strain should be prepared by inoculating an appropriate growth media, such as Tryptic Soy or Trypticase Soy broth, supplemented with 1% glucose and incubating for 18 to 24 hours at 37°C to obtain stationary phase cells. The additional glucose is added to ensure that the inoculum is pre-adapted for acid tolerance. Cultures should be grown the day prior to product inoculation with a minimum holding period prior to actual use. Each strain should be centrifuged, washed and resuspended in 0.1% peptone broth. Dilutions of each strain should be made to yield approximately equal numbers of each of the five strains. The five strains should be thoroughly mixed prior to being used as an inoculum. After the mixed working inoculum is prepared, the viable count of the mixture should be determined by direct surface plating on MacConkey sorbitol agar (MSA). Each of the individual strains in the inoculum should contribute about 20% of the total inoculum.
- Size of inoculum to be used: The final concentration of E. coli O157:H7 in the meat mixture should be no less than 2.0 × 107 CFU/g of meat mixture. The actual inoculum level in the meat mixture should be confirmed by sampling the inoculated meat mixture immediately after the inoculation using the above media. At this concentration, product can be serially diluted and direct plated without the need for enrichment to recover low levels of inoculum. The initial inoculum level was chosen to allow direct enumeration of at least a 5 log reduction in the level of the inoculum between the initial count in the meat mixture and the finished product.
- Method of inoculation to be used: The inoculum must be added to the meat and mixed prior to the addition of the other ingredients or a starter culture to the meat mixture. The use of a non-inhibitory, food grade, green dye added to the inoculum may aid in determining the uniform distribution of inoculum. The following procedure is recommended:
- add inoculum to meats while grinding or chopping the meats to the desired consistency;
- mix in cure (if used), salt and spices;
- blend in starter culture (if used) near end of mixing cycle; and
- stuff batter into casings.
- Stuffing product into casings: Inoculated product should be stuffed into casing as usual to approximate normal production procedures. A shorter length may be used as long as the length is approximately twice the diameter of the stuffed casing.
- Sample size, sampling time, sampling location and number of samples to test: Select two sausage sticks at the end of the drying period (finished product). From each stick selected, cut multiple cross-sectional slices from multiple locations on each stick to a final analytical sample weight of 25 g per stick.
- Methods of microbial analysis: Blend each of the two 25 gram samples (one per stick) in separate 225 ml portions of buffered peptone water. Serially dilute the homogenates in buffered peptone water and surface plate 0.1 ml portions from the dilutions onto MSA plates in duplicate. Count plates after incubation at 42°C overnight. Confirm 5-10 randomly selected colonies by serological and biochemical methods as necessary. Report count per gram of finished product. Report initial inoculum level.
- Number of replicates: A minimum of three replicates of the study should be performed. Three separate formulation batches can, however, be processed concurrently following stuffing.
Therefore, total number of samples for microbiological analysis:
Time zero (0) = 2
After fermentation = 0
During drying = 0
End drying = 2
Total = 4
Number of replicates × 3
Total samples = 12 - Measurement of process parameters used to determine when a product is finished at each stage of production (control program criteria): Duplicate uninoculated samples of the product which are collected after stuffing and at each production stage should be assayed for moisture, fat, protein, salt content, pH, aw, and titratable acidity.
Therefore, total number of samples for additional analysis:
Time zero (0) = 2
After fermentation = 2
During drying = 2
End drying = 2
Total = 8
Number of replicates × 3
Total samples = 24
Control of pathogens in dried products
This form of preservation depends on a lowering of the water activity (aw) of the product to inhibit the growth of microorganisms through, for instance, freeze drying or salting. It should be considered that a reduction in water activity neither destroys microorganisms nor toxins; it only retards the growth of microorganisms. Therefore, the operator should have controls in place to assess the incoming product.
Control of E. coli O157 in dried beef products
As dried beef products may pose a hazard associated with E. coli O157:H7, these products must be submitted to a heat treatment before the drying process.
The following methods have been found acceptable for this purpose:
- cooking the product so it reaches an internal temperature of 71°C for 15 seconds before starting the drying process;
- a process validated as achieving a 5 log10 (5D) reduction in E. coli O157:H7. Refer to Option 1 above for recognized processing parameters.
Shelf stable fermented and dried meat products
In accordance with Safe Food for Canadians Regulations 286, fermented and dried products are considered "shelf stable" and do not require refrigeration if:
- The pH of the finished product is of 4.6 or less, regardless to its final aw; or
- The aw of the finished product is 0.85 or less, regardless of its final pH.
A fermented meat product is also considered shelf stable if the pH is 5.3 or lower at the end of the fermentation period and the end product has an aw of 0.90 or lower.