Fermentation Standards for Making Fermented Sausages

USA Standards for Making Fermented Sausages

Fermented sausages must be fermented within certain time, otherwise product will spoil and might become dangerous.

In the USA the Food Safety and Inspection Service of the United States department of Agriculture requires that the shelf-stable dry sausages be nitrite cured, fermented, smoked, reach a final pH of 5.0 or less, and have a moisture/protein ratio of 1.9:1 or less.

Dry sausages are products that, as a result of bacterial action or direct acidulation should reach a pH of 5.3 or less and are then dried to remove 25-50% of the moisture, resulting in a moisture/protein ratio complying with the standards.

Semi-dry sausages are products, that as a result of bacterial action or direct acidulation should reach a pH of 5.3 or less and are then dried to remove 15% of the moisture, resulting in a moisture/protein ratio of 3.1:1 or less. Some semidry susages receive a pasteurization treatment following the fermentation period and some are shelf stable. Since the pH is lowered during the fermentation period, the degree-hour concept applies only to the time required to reach a pH of 5.3.

Fermented and acidulated sausages (citric acid, lactic acid or GDL added) shall attain a pH of 5.3 or lower within the proper time frame (defined in temperature-degrees below) in order to control the growth of pathogenic bacteria such as E. coli 0157:H and Staphylococcus aureus.

During fermentation of sausages to a pH 5.3, it is necessary to limit the time during which the sausage is exposed to temperatures exceeding 60° F (15.6° C), otherwise the product will spoil, even though the recommended pH was attained. This time frame is temperature dependent and these are the following criteria:

Time in F degree-hours above 60° F (16° C) Maximum chamber temperature
less than 1200 less than 90° F (32° C)
< 1000 90-100° F (32-38° C)
< 900 greater than 100° F (38° C)

Degrees are measured as the excess over 60° F (15.6° C), the critical temperature at which staphylococcal growth effectively begins.

Constant Temperature Fermentation

Time in F degree-hours above 60° F (16° C) Chamber temperature Maximum hours to pH 5.3
° F ° C
1200 75 24 80
1200 80 27 60
1200 85 30 48
1000 90 32 33
1000 95 35 28
1000 100 38 25
900 105 41 20
900 110 44 18

The above table provides maximum hours that a product may be fermented at given constant fermentation temperature (measured in ° F) to obtain pH 5.3. For example, at 80° F constant temperature a sausage must reach pH 5.3 within 60 hours or less. Those hours can also be calculated for any temperature and the

Example A: Sausage fermented for 48 hours at the constant temperature 86° F (30° C) to pH of 5.3.

For the calculation time in degrees over 60° F (16° C) is taken and:

Degrees: 86 - 60 = 26

Hours: 48

Degree-hours (above 60° F) = 26 x 48 = 1248 degree hours. The result fails the guidelines of 1200 degree-hours by 48 hours. The time has to be decreased by 2 hours:

Degree-hours = 26 x 46 = 1196 degree-hours. Process A passes guidelines of 1200 degree-hours.

Example B: Constant 90° F for 40 hours with a pH decline to 5.3

Degrees: 90 - 60 = 30

Hours: 40

Degree-hours: 30 x 40 = 1200 degree-hours

Process B fails the guideline limit of 1000 degree-hours.

Variable Temperature Fermentation

In many cases fermentation proceeds at different temperatures and for each temperature setting, a separate degree-hours are calculated and then added together. In testing each process, each step-up in the progression is analyzed for the number of degree-hours it contributes, with the highest temperature used in the fermentation process determining the degree-hour limitation. Degree hours is calculated for each temperature during fermentation.

Example C

Time in F degree-hours above 60° F (16° C) Chamber temperature° F Adjusted Temperature Degrees Result Maximum hours to pH 5.3
10 hrs 75 75 - 60 = 15 10 x 15 = 150
10 hrs 85 85 - 60 = 25 10 x 25 = 250
14 hrs 95 95 - 60 = 35 14 x 35 = 490
Total F degree-hours: 890

In the above example a product was fermented at three different temperatures (75, 85 and 95° F) for a total time of 34 hours. The total sum of the calculated degree-hours is 890 hours which is less than the maximum of 1000 hours for 90 - 100° F temperature range. Process C passes the guidelines.

Example D

Time in F degree-hours above 60° F (16° C) Chamber temperature ° F Adjusted Temperature Degrees Result Maximum hours to pH 5.3
10 hrs 75 75 - 60 = 15 10 x 15 = 150
12 hrs 85 85 - 60 = 25 12 x 25 = 300
18 hrs 98 98 - 60 = 38 18 x 38 = 684
Total F degree-hours: 1134

Process D fails the guideline because the limit is set at 1000 degree-hours for these times and temperatures and the process has taken 1134 degree-hours to reach pH 5.3

Understanding these tables is of utmost importance as one can set his own fermentation temperatures and times without blindly relaying on unproven recipes and be in strict compliance with the government standards. Besides, it provides a great deal of satisfaction knowing that the process is safe and that we are in total control.

Canadian Fermentation Standards for Making Fermented Sausages

(MH MOP, Chapter 14.10.3 (15) - Fermented Meat Products)

As most of the world uses metric system we enclosing Canadian Food Inspection Agency standards for fermentation times which are based on degrees Centigrade. Those standards are based on degree/temperatures and the same starting temperature of 15.6° C (60° F) is used. At this temperature (15.6° C, 60° F) Staphylococcus aureus starts to grow and produce toxins.

Degree/Hours are the product of time as measured in hours at a particular fermentation temperature multiplied by the degrees over 15.6° C (60° F).

Degree/hours = time (hours) x temperature in excess of 15.6° C (60° F). Fermented sausage must reach pH 5.3 or lower within certain time, depending on temperature. The reason being that at pH < 5.3 Staphylococcus aureus growth is inhibited.

Time in C degree-hours above 15.6° C (60° F) Maximum fermentation temperature
less than 665 less than 33° C, (90° F)
< 555 33-37° C (90 - 100° F)
< 500 greater than 37° C, (100° F)

Constant Temperature Fermentation

The table below provides maximum hours that a product may be fermented at given constant fermentation temperature (measured in ° C) to obtain pH 5.3. For example at 86° F constant temperature a sausage must reach pH 5.3 within 46.2 hours or less. Those hours can also be calculated for any temperature and the following examples demonstrate how.

Degree (C)-hours limit for the corresponding temperature Chamber temperature Maximum hours to pH 5.3
° F ° C
665 68 20 150.0
665 71.6 22 103.4
665 75.2 24 78.9
665 78.8 26 63.8
665 82.4 28 53.6
665 86 30 46.2
665 89.6 32 40.5
555 91.4 33 31.8
555 93.2 34 30.1
555 95 35 28.6
555 96.8 36 27.2
555 98.6 37 25.9
500 100.4 38 22.3
500 104 40 20.5
500 107.6 42 18.9
500 111.2 44 17.6
500 114.8 46 16.4
500 118.4 48 15.4
500 122 50 14.5

Example A: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 - 15.6 = 10.4

Hours to reach pH of 5.3: 55

Degree/Hours calculation:(10.4) x (55) = 572 degree/hours

The corresponding degree/hours limit (less than 33° C) is 665 degree/hours.

Conclusion: Process A passes the test because its degree/hours is less than the limit.

Example B: 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 - 15.6 = 19.4

Hours to reach pH of 5.3:  40

Degree/Hours calculation: (19.4) x (40) = 776 degree/hours

The corresponding degree/hours limit (between 33 and 37° C) is 555 degree/hours.

Conclusion: Process B fails the test because its degree/hours exceeds the limit.

Example C: Fermentation Room temperature is a constant 25° C. It takes 60 hours for the pH to reach 5.3.

Degrees above 15.6° C: 25 - 15.6 = 9.4

Hours to reach pH of 5.3: 60

Degree/Hours calculation: (9.4) x (60) = 564 degree/hours

The corresponding degree/hours limit (less than 33° C) is 665 degree/hours.

Conclusion: Process C passes the test because its degree/hours is less than the limit.

Variable Temperature Fermentation

In many cases fermentation proceeds at different temperatures and for each temperature setting, a separate degree-hours are calculated and then added together. In testing each process, each step-up in the progression is analyzed for the number of degree-hours it contributes, with the highest temperature used in the fermentation process determining the degree-hour limitation. Degree hours is calculated for each temperature during fermentation.

Example D: 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.

Time in C degree-hours above 15.6° C (60° F) Chamber temperature ° C Adjusted Temperature Degrees Result Maximum hours to pH 5.3
10 24 24 - 15.6 = 8.4 8.4 x 10 =  84
10 30 30 - 15.6 = 14.4 14.4 x 10 = 144
15 35 35 - 15.6 = 19.4 19.4 x 15 = 291
Total C degree-hours: 519

The highest temperature reached = 35° C

The corresponding degree/hour limit = 555 (between 33 and 37° C)

Conclusion: Process D passes the test because its degree/hours is less than the limit.

Example E: 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 second 10 hours and 37° C for the final 18 hours.

Time in C degree-hours above 15.6° C (60° F) Chamber temperature ° C Adjusted Temperature Degrees Result Maximum hours to pH 5.3
10 24 24 - 15.6 = 8.4 8.4 x 10 = 84
10 30 30 - 15.6 = 14.4 14.4 x 10 = 144
18 37 37 - 15.6 = 21.4 21.4 x 18 = 385.2

Total C degree-hours:

613.2

The highest temperature reached = 37° C

The corresponding degree/hour limit = 555 (between 33 and 37° C)

Conclusion: Process E fails the test because its degree/hours exceeds the limit.

Quote from The Canadian Food Inspection Agency "Meat Hygiene Manual of Procedures" - Chapter 4:

(iv) Disposition of lots which have not met degree/hours limits:

The inspector in charge must be notified of each case where degree/hours limits have been exceeded. Such lots must be held and samples of product submitted for microbiological laboratory examination after the drying period has been completed. Analyses should be done, at least for Staphylococcus aureus and its enterotoxin, and for principal pathogens such as E. coli O157:H7, Salmonella, Listeria monocytogenes, etc.

Safety Options And Examples of Validated Processes

Prior to 1994 there were no specific rules controlling the manufacture of fermented sausages in the USA. Then, at the end of 1994 about two dozen cases of E.coli 0157:H7 poisoning were reported in the Pacific North West and in Northern California. This outbreak of E.coli 0157:H7 poisoning was attributed to the consumption of dry sausages. More cases associated with E.coli 0157:H7 followed in Australia (1995) and Canada (1998, 1999). To date, outbreaks of E.coli 0157:H7 linked to consumption of dry/semidry fermented sausages have been associated with beef meat ingredients.

The USDA panicked and following the 1994 US outbreak, a set of stringent regulations was introduced and aimed at commercial producers. In 1966 the final protocol was drafted which requires commercial producers of dry and semidry fermented sausages to follow 1 of 5 safety options:

  1. utilize a heat process as listed in 9 Code of Federal Regulations, 318.17 - achieve a 5-log kill using a heat process (145º F, 63º C) for 4 minutes (5-log kill is the time required to destroy 90% of the organisms present).
  2. include a validated 5 log inactivation treatment
  3. conduct a "hold and test" program. This option requires finished product testing and is expensive.
  4. propose other approaches to assure 5-log kill.
  5. initiate a hazard analysis critical point (HACCP) system that includes raw batter testing and a 2-log inactivation in fermentation and drying.

All those options must address Salmonella, Trichinella and Staphylococcus. FSIS expanded the Staphylococcus aureus monitoring program to include E.coli 0157:H7. Since some fermented products are fully cooked, it should be reiterated that thorough cooking destroys E.coli 0157:H7, post process contamination must be avoided. At the same time, it has been concluded that Salmonella may also be found in the resulting product.

These regulations created a nightmare for little producers and some stopped making fermented products altogether, others removed beef from recipes and others reluctantly started to cook the sausages.

It is strongly advisable that the reader becomes familiar with the first two options as they can be easily adapted to home conditions. Options 3-5 require in house laboratory testing and will be utilized by commercial meat processors.

Option 1. Include as part of the manufacture of the sausage, one of the following heat process which is recognized as controlling E.coli 0157:H7.

Minimum Internal Temperature Minimum processing time in minutes after the minimum temperature has been reached
º F º C
130 54.4 121 min
131 55.0 97 min
132 55.6 77 min
133 56.1 62 min
134 56.7 47 min
135 57.2 37 min
136 57.8 32 min
137 58.4 24 min
138 58.9 19 min
139 59.5 15 min
140 60.0 12 min
141 60.6 10 min
142 61.1 8 min
143 61.7 6 min
144 62.2 5 min
145 62.8 4 min

Option 2. Use a manufacturing process (combination of fermentation, heating, holding and/drying) which has already been scientifically validated to achieve a 5 log kill of E. coli 0157:H7.

The following processes have been scientifically validated as achieving a 5-log kill or greater reduction of E. coli 0167H:7.

Fermentation Chamber Temperature pH at the end of fermentation process Casing diameter Subsequent process (dry, hold or cook) Reference
º F º C
70 21 > 5.0 < 55 mm heat (1 hr @ 110º F and 6 hours @ 125º F) 1
90 32 < 4.6 < 55 mm hold @ 90º F for > 6 days 1
90 32 < 4.6 < 55 mm heat (1 hr @ 110º F, then 6 hrs @ 125º F) 1
90 32 < 4.6 56 - 105 mm heat (1 hr at 100º F, 1 hr @ 110º F, 1 hr @ 120º F, then 7 hrs @ 125º F). 1
90 32 > 5.0 56 - 105 mm heat (1 hr at 100º F, 1 hr @ 110º F, 1 hr @ 120º F, then 7 hrs @ 125º F). 1
96 36 < 5.0 < 55 mm heat (128º F internal product temperature x 60 minutes) and dry (at 55º F and 65% relative humidity to a moisture protein ratio of < 1.6:1) 2
110 43 < 4.6 < 55 mm hold @ 110º F for > 4 days 1
110 43 < 4.6 56 - 105 mm hold @ 110º F for > 4 days 1
110 43 > 5.0 56 - 105 mm hold @ 110º F for > 4 days 1

Ref. 1: Nicholson, R., et al, Dry fermented sausages and Escherichia coli 0157:H7. National Cattlemen’s Beef Association, Research Report Number 11-316, Chicago, Illinois, 1996.

Ref. 2: Hinkens, J.C., et al, Validation of Pepperoni Processes for Control of Escherichia coli 0157:h7, Journal of Food Protection, Volume 59, Number 12, 1996, pp.1260-1266.

Examples of Validated Processes

Because there are so many different combinations of factors that impact the safety and stability of fermented sausages, it is hard to come up with one validation study that will apply in each case, A commonly used process that has been validated is to achieve a pH < 5.0, followed by a heat process to achieve 128º F (53.3º C) internal temperature for 1 hour.

Summer Sausage - the sausage is fermented with a starter culture at 110º F, (43.3º C) until the pH is 4.7 or lower, then cooked to 152º F (66.7º C) internal meat temperature. The final pH 4.4, Aw 0.964.

Pepperoni - the sausage is fermented with a starter culture at 102º F, (38.9 º C) until the pH is 5.7 or lower, then cooked to 128º F (53.3º C) internal meat temperature. The final pH 4.7, Aw 0.896.

In the majority of cases fermented sausages are made from a combination of pork and beef. Using safety option 1 or 2 takes care of E.coli 0157:H7 and Salmonella. Cold temperature, cleanliness and proper sanitation procedures take care of Listeria monocytogenes. Nevertheless, pork must be taken care of as it may be contaminated with trichinae. If pork meat was not previously frozen according to the government standards for destruction of Trichinae (see Appendix A), it must be heat treated:

Heat treatment to ensure destruction of Trichinella in pork
Minimum internal temperature Minimum time in minutes
º F º C
130 54 60
131 55 30
133 56 15
135 57 6
136 58 3
138 59 2
140 60 1
142 61 1
144 62 1
145 63 instant

It can be noted (Option 1 above) that the heat treatment of the sausage for destruction of E. coli 0157:H7 will take care of trichinae as well.