Safety
What curing is doing, and what can go wrong
A drying salami is an anaerobic, low-acid mass held at room temperature. That is not an analogy for the environment Clostridium botulinum requires; it is the environment. Curing is the practice of making that environment survivable by other means, and the parameters below are what published sources say those means are.
The position this site takes
This site publishes parameters and their sources. It does not tell anyone that a preparation is safe, because it cannot inspect a product, and because "safe" is a conclusion about a specific thing rather than a property of a recipe. Where a source publishes a figure, the figure is here with the citation. Where no source publishes one, this site says so instead of supplying a number.
The hazards
Botulism
Clostridium botulinum
A spore-forming organism that grows without oxygen, in low-acid food, at ambient temperature, and produces a neurotoxin as it does.
Staphylococcal enterotoxin
Staphylococcus aureus
Grows at a lower water activity than the other pathogens, and produces a heat-stable toxin. Cooking the product afterwards does not remove the toxin.
Listeriosis
Listeria monocytogenes
Grows at refrigeration temperature. Recontaminates ready-to-eat product after the lethality step, from surfaces and hands.
Salmonellosis, haemolytic uraemic syndrome
Salmonella and shiga-toxin producing E. coli
Present on raw meat. Tolerates drying and adapts to acid, so neither fermentation nor drying reliably removes it.
Trichinellosis
Trichinella spiralis
A parasite in pork muscle. Killed by heat, by sustained freezing, or by a validated curing and drying schedule.
Perfringens food poisoning
Clostridium perfringens
A spore former that multiplies rapidly through the cooling range if a heated product is allowed to sit in it.
Mycotoxins and spoilage
Moulds
High salt and low temperature do not inhibit moulds, so a curing chamber is a good place for them.
The three numbers most often wanted
Shelf stability, Staphylococcus aureus
- Stored in air
- aw 0.85
- Vacuum packed in oxygen-impervious film
- aw 0.91
FSIS Compliance Guideline for Meat and Poultry Jerky, FSIS-GD-2014-0010. Applied to other shelf-stable meat and poultry products by FSIS-GD-2023-0002.
Clostridium botulinum
- Sodium nitrite
- 50 ppm
- or water activity
- 0.92 or below
- Stabilisation, aw
- 0.93 or less
- Stabilisation, pH
- 4.6 or less
FSIS-GD-2023-0002 for the first two, FSIS-GD-2021-0013 (revised Appendix B) for the second two.
Fermentation, Staphylococcus aureus
- Base temperature
- 60 F
- Target pH
- 5.3 or below
- Derived ceiling
- 900 degree-hours
110 F less the 60 F base is 50 degrees. 50 degrees for 18 hours is 900 degree-hours. FSIS calls 18 hours at 110 F the maximum allowable, so 900 degree-hours is what that sentence means at that temperature. FSIS does not itself publish a table of maxima.
Trichinella: the published treatments
These are the tables that were 9 CFR 318.10 until 2018 and are now FSIS guidance. They are reproduced here because they are the most specific parameters the federal government has ever published for curing pork, and because they are parsed from the guideline rather than retyped.
| Internal temperature, F | C | Minimum time |
|---|---|---|
| 120 | 49 | 21 hours |
| 122 | 50 | 9.5 hours |
| 124 | 51.1 | 4.5 hours |
| 126 | 52.2 | 2.0 hours |
| 128 | 53.4 | 1.0 hour |
| 130 | 54.5 | 30 minutes |
| 132 | 55.6 | 15 minutes |
| 134 | 56.7 | 6 minutes |
| 136 | 57.8 | 3 minutes |
| 138 | 58.9 | 2 minutes |
| 140 | 60 | 1 minute |
| 142 | 61.1 | 1 minute |
| 144 | 62.2 | Instant |
| Temperature, F | Group 1, days | Group 2, days |
|---|---|---|
| 5 | 20 | 30 |
| -10 | 10 | 20 |
| -20 | 6 | 12 |
| Temperature, F | C | Hours |
|---|---|---|
| 0 | -17.8 | 106 |
| -5 | -20.6 | 82 |
| -10 | -23.3 | 63 |
| -15 | -26.1 | 48 |
| -20 | -28.9 | 35 |
| -25 | -31.7 | 22 |
| -30 | -34.5 | 8 |
Worth noticing: a domestic freezer usually sits near 0 F, and the Table 2 schedule starts at 5 F for 20 days. The Table 2A route at 0 F is 106 hours, but it is measured at the centre of the meat rather than as an air temperature.
Common questions
Is drying a sausage a kill step?
No. FSIS states that drying the product does not necessarily result in an adequate reduction of Salmonella, because the pathogen can be resistant to drying. It also states that fermentation itself is not a particularly effective lethality treatment. Reaching a shelf-stable water activity means the product will not support growth; it does not mean what was there at the start has gone.
What water activity makes a cured product shelf stable?
FSIS recommends 0.85 or below for product stored in air, and 0.91 or below for product vacuum packed in oxygen-impervious film. Both figures come from the FSIS Compliance Guideline for Meat and Poultry Jerky, and both are limits for Staphylococcus aureus rather than for anything else.
How much nitrite may go into a cured meat?
It depends on the product class. 9 CFR 424.21(c) permits a quarter of an ounce of sodium nitrite per 100 lb of chopped meat, which is 156.25 parts per million, and one ounce per 100 lb in a dry cure, which is 625 ppm. The finished product may not exceed 200 ppm calculated as sodium nitrite. Bacon has its own figures in 9 CFR 424.22(b): 120 ppm for pumped or immersion cured, 200 ppm for dry cured.
What are degree-hours?
FSIS defines degree-hours as the time in hours above 60 F, the temperature at which staphylococcal growth effectively begins, that a fermentation takes to reduce the pH to 5.3 or below. Degrees are the excess over 60 F and are multiplied by the hours at that temperature. FSIS does not publish a table of maximum degree-hours; it points at an American Meat Institute document.
Does the federal government still prescribe a trichinae treatment for pork?
No. 9 CFR 318.10 prescribed heating, freezing and curing treatments until it was removed effective 30 July 2018 by the rule at 83 FR 25302. The same parameters now appear in FSIS guidance, unchanged, in the Compliance Guideline for the Prevention and Control of Trichinella.
Where the drying schedule is
The Trichinella drying room tables, with the reductions for a warm hold and the increases for reduced salt, are on the drying schedule calculator. The withdrawn 9 CFR 318.10 text is at the withdrawn trichinae treatment section.
Source: FSIS Compliance Guideline for the Prevention and Control of Trichinella and Other Parasitic Hazards in Pork and Products Containing Pork (FSIS-GD-2016-0002), March 2016. Tables parsed from the guideline text, retrieved 2026-09-04. These parameters were codified at 9 CFR 318.10 until that section was removed effective 30 July 2018 (83 FR 25302). FSIS now publishes them as guidance: an establishment may use them, or validate something else. They are not a legal minimum.