Calculating Maximum Fermenting Times

The US and Canadian governments have rules limiting the amount of time that a salami can be held above 15.6°C (60°f) for fermentation of cultures. They are very similar other than one uses Fahrenheit and the other centigrade. It’s the Canadian rules (centigrade) that I’ll use for this explanation.

The rules use a calculation based on what is termed degree hours. The salami must reach a pH of 5.3 within a set number of degree hours. This is the number of hours that the salami is above 15.6°C multiplied by the amount that the temperature exceeds 15.6°C:

Degree hours = hours x temperature in excess of 15.6° C (60° F)

This number of degree hours is limited depending on the temperature being used:

  • Below 33° C – degree hours must be below 665 hours
  • 33-37° C – degree hours must be below 555 hours
  • Over 37° C – degree hours must be below 500 hours

An example would be that if we ferment at 25°C the permitted hours would be:

665 / (25-15.6) = 70.7 hours are permitted for the pH to drop below 5.3 – that’s just under 3 days.

If the temperature varies you should calculate for each temperature. However, if it passes a calculation for the highest temperature used this is unnecessary.

The calculator below can be used in two ways: Complete the temperature to see the permitted degree hours and hours to reach pH 5.3, or complete both boxes to validate your ferment.

Fermentation – Degree Hours
Temperature in degrees C °C
Hours fermenting hours
Degree hours permitted degree hours
Maximum actual hours permitted to reach pH5.3 hours
Degree hours used degree hours
Further Information:

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